INDENTURE

Exhibit 4.1

CELL THERAPEUTICS, INC.,

as Company

U.S. BANK NATIONAL ASSOCIATION,

as Trustee

INDENTURE

Dated as of June 12, 2008

15% CONVERTIBLE SENIOR NOTES DUE 2011

TABLE OF CONTENTS

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CROSS-REFERENCE TABLE*

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INDENTURE , dated as of June 12, 2008, between Cell Therapeutics, Inc., a corporation duly organized and existing under the laws of the State of Washington, having its principal office at 501 Elliott Avenue West, Suite 400, Seattle, Washington 98119 (herein called the “ Company ”), and U.S. Bank National Association, as Trustee hereunder (herein called the “ Trustee ”).

RECITALS OF THE COMPANY

The Company has duly authorized the creation of an issue of its 15% Convertible Senior Notes due 2011 (herein called the “ Securities ”), of substantially the tenor and amount hereinafter set forth, and to provide therefor the Company has duly authorized the execution and delivery of this Indenture.

All things necessary to make the Securities, when the Securities are executed by the Company and authenticated and delivered hereunder, the valid obligations of the Company and to make this Indenture a valid agreement of the Company, in accordance with their and its terms, have been done. Further, all things necessary to duly authorize the issuance of shares of common stock of the Company issuable upon the conversion of the Securities, and to duly reserve for issuance the number of shares of Common Stock issuable upon such conversion, have been done.

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

For and in consideration of the premises and the purchase of the Securities by the Holders thereof, it is mutually covenanted and agreed, for the equal and proportionate benefit of all Holders of the Securities, as follows:

ARTICLE I

DEFINITIONS AND OTHER PROVISIONS

OF GENERAL APPLICATION

SECTION 1.1 Definitions.

For all purposes of this Indenture, except as otherwise expressly provided or unless the context otherwise requires:

(a) the terms defined in this Article I have the meanings assigned to them in this Article I and include the plural as well as the singular;

(b) all accounting terms not otherwise defined herein have the meanings assigned to them in accordance with generally accepted accounting principles in the United States; and

(c) the words “ herein ,” “ hereof ” and “ hereunder ” and other words of similar import refer to this Indenture as a whole and not to any particular Article, Section or other subdivision.

“ Act ,” when used with respect to any Holder of a Security, has the meaning specified in Section 1.4(a) .

“ Affiliate ” of any specified Person means any other Person directly or indirectly controlling or controlled by or under direct or indirect common control with such specified Person. For the purposes of this definition, “control,” when used with respect to any specified Person, means the power to direct the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise; and the terms “controlling” and “controlled” have meanings correlative to the foregoing.

“ Agent Members ” means a member of, or a participant in, the Depositary.

“ Aggregate Current Market Price ” has the meaning specified in Section 10.4(e) .

“ American Depository Shares ” means US. Dollar denominated forms of equity ownership held in deposit in a custodian bank and evidenced by physical certificates of ownership (“American Depositary Receipts”) issued by a U.S. bank.

“ Applicable Procedures ” means, with respect to any transfer or transaction involving a Global Security or beneficial interest therein, the rules and procedures of the Depositary for such Security, to the extent applicable to such transaction and as in effect from time to time.

“ Authenticating Agent ” means any Person authorized pursuant to Section 5.12 to act on behalf of the Trustee to authenticate Securities.

“ Authorized Share Approval ” means (i) vote by the shareholders of the Company to approve an amendment to the Company’s articles of incorporation that increased the number of authorized shares of Common Stock and authorizes the board of directors of the Company to effect such increase (the “Amendment”) and (ii) the filing by the Company of the Amendment with the Secretary of State of the State of Washington and the acceptance of the Amendment by the Secretary of State of the State of Washington.

“ Automatic Conversion ” has the meaning specified in Section 10.13 .

“ Automatic Conversion Date ” has the meaning specified in Section 10.13 .

“ Automatic Conversion Notice ” has the meaning specified in Section 10.13 .

“ Board of Directors ” means either the board of directors of the Company or any duly authorized committee of that board.

“ Board Resolution ” means a resolution duly adopted by the Board of Directors, a copy of which, certified by the Secretary or an Assistant Secretary of the Company to have been duly adopted by the Board of Directors and to be in full force and effect on the date of such certification, shall have been delivered to the Trustee.

“ Business Day ,” when used with respect to any Place of Payment, Place of Conversion or any other place, as the case may be, means each Monday, Tuesday, Wednesday, Thursday and Friday that is not a day on which banking institutions in such Place of Payment, Place of Conversion or other place, as the case may be, are authorized or obligated by law or executive order to close; provided, however , that a day on which banking institutions in New York, New York are authorized or obligated by law or executive order to close shall not be a Business Day for purposes of Section 10.5 .

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“ Cash Equivalents ” means (1) securities issued or directly and fully guaranteed or insured by the United States government or any agency or instrumentality thereof ( provided that the full faith and credit of the United States is pledged in support thereof) having maturities of not more than six months from the date of acquisition, (2) certificates of deposit and eurodollar time deposits with maturities of six months or less from the date of acquisition, bankers’ acceptances with maturities not exceeding six months and overnight bank deposits, in each case with any domestic commercial bank having capital and surplus in excess of $500 million and a Thompson Bank Watch Rating of “B” or better, (3) repurchase obligations with a term of not more than seven (7) days for underlying securities of the types described in clause (1) above entered into with any financial institution meeting the qualifications specified in clause (2) above, (4) commercial paper having the highest rating obtainable from Moody’s Investors Service, Inc. or Standard & Poor’s Ratings Services and in each case maturing within six months after the date of acquisition and (5) money market funds at least ninety-five percent (95%) of the assets of which constitute Cash Equivalents of the kinds described in clauses (1)-(4) of this definition.

“ Change in Control ” means the occurrence at any time, after the original issuance of the Securities, of any of the following events:

(1) the acquisition by any Person (including any syndicated group that would be deemed to be a “person” under Section 13(d)(3) of the Exchange Act) of beneficial ownership, directly or indirectly, through a purchase, merger or other acquisition transaction or series of transactions, of shares of capital stock of the Company entitling such Person to exercise more than thirty three percent (33%) of the total voting power of all shares of capital stock of the Company entitled to vote generally in the elections of directors, other than any such acquisition by the Company, any Subsidiary or any employee benefit plan of the Company; or

(2) any Person shall succeed in having sufficient of its nominees (who are not supported by a majority of the then current Board of Directors of the Company) elected to the Board of Directors of the Company such that such nominees, when added to any existing directors remaining on the Board of Directors of the Company after such election who are Affiliates of or acting in concert with any such Person, shall constitute a majority of the Board of Directors of the Company; or

(3) any consolidation or merger of the Company with or into any other Person, or any merger of another Person with or into the Company (other than (A) a merger (i) that does not result in any reclassification, conversion, exchange or cancellation of outstanding shares of the Company’s capital stock and (ii) pursuant to which holders of Common Stock immediately prior to such transaction have, directly or indirectly, sixty seven percent (67%) or more of the total voting power of all shares of capital stock or other ownership interests entitled to vote generally in the election of directors of the continuing or surviving Person immediately after such transaction and (B) any merger that is effected solely to change the jurisdiction of incorporation of the Company and results in a reclassification, conversion or exchange of outstanding shares of Common Stock solely into shares of common stock of the Company or another Person); or

(4) any conveyance, transfer, sale, lease or other disposition of all or substantially all of the Company’s assets to another Person.

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For the purposes of this definition, “beneficial owner,” has the meaning attributed to it in Rules 13d-3 under the Exchange Act, whether or not applicable.

“ Closing Price ” means, with respect to the Common Stock on any day, the closing sale price regular way on such day or, in the case where no such sale takes place on such day, the average of the reported closing bid and asked prices, regular way, in each case on the Nasdaq Global Market or New York Stock Exchange, as applicable, or, if the Common Stock is not listed or admitted to trading on such National Market or Exchange, on the principal national security exchange or quotation system on which such security is quoted or listed or admitted to trading, or, if not quoted or listed or admitted to trading on any national securities exchange or quotation system, the average of the closing bid and asked prices of the Common Stock on the over-the-counter market on the day in question as reported by the National Quotation Bureau Incorporated, or a similar generally accepted reporting service, or if not so available, in such manner as furnished by any New York Stock Exchange member firm selected from time to time by the Board of Directors for that purpose, or if no bid or asked price is available a price determined in good faith by the Board of Directors, whose determination shall be conclusive and described in a Board Resolution.

“ Code ” has the meaning specified in Section 2.1 .

“ Combined Cash and Tender Amount ” has the meaning specified in Section 10.4(e) .

“ Combined Tender and Cash Amount ” has the meaning specified in Section 10.4(f) .

“ Commission ” means the United States Securities and Exchange Commission, as from time to time constituted, created under the Exchange Act, or, if at any time after the execution of this instrument such Commission is not existing and performing the duties now assigned to it under the Trust Indenture Act, then the body performing such duties at such time.

“ Common Stock ” means the shares of the class designated as common stock of the Company at the date of this Indenture or as such stock may be reconstituted from time to time. Subject to the provisions of Section 10.11 , shares issuable on conversion or repurchase of Securities shall include only shares of Common Stock or shares of any class or classes of common stock resulting from any reclassification or reclassifications thereof; provided , however , that if at any time there shall be more than one such resulting class, the shares so issuable on conversion of Securities shall include shares of all such classes, and the shares of each such class then so issuable shall be substantially in the proportion that the total number of shares of such class resulting from all such reclassifications bears to the total number of shares of all such classes resulting from all such reclassifications.

“ Company ” means the Person named as the “Company” in the first paragraph of this instrument until a successor Person shall have become such pursuant to the applicable provisions of this Indenture, and thereafter “Company” shall mean such successor Person.

“ Company Notice ” has the meaning specified in Section 12.2(a) .

“ Company Request ” or “ Company Order ” means a written request or order signed in the name of the Company by its Chairman of the Board, its Vice Chairman of the Board, its Chief Executive Officer, its President or a Vice President, and by its principal financial officer, Treasurer, an Assistant Treasurer, its Secretary or an Assistant Secretary, and delivered to the Trustee.

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“ Completion Date ” has the meaning specified in Section 10.4(f) .

“ Constituent Person ” has the meaning specified in Section 10.11 .

“ Conversion Agent ” means any Person authorized by the Company to convert Securities in accordance with Article X . The Company has initially appointed the Trustee as its Conversion Agent.

“ Conversion Price ” means the amount equal to U.S. $1,000 divided by the Conversion Rate.

“ Conversion Date ” means the date on which both the Securities and the duly signed and completed notice have been delivered to the Trustee.

“ Conversion Rate ” has the meaning specified in Section 10.1 .

“ Conversion Shares ” has the meaning specified in Section 10.4(m) .

“ Corporate Trust Office ” means the office of the Trustee at which at any particular time the trust created by this Indenture shall be administered (which at the date of this Indenture is located at 633 West Fifth Street, 24th Floor, Los Angeles, CA 90071, Attn: Corporate Trust Services (Cell Therapeutics, Inc. – 15% Convertible Senior Notes due 2011)).

“ Corporation ” means a corporation, company, association, joint-stock company or business trust.

“ Defaulted Interest ” has the meaning specified in Section 2.8 .

“ Depositary ” means, with respect to any Registered Securities, a clearing agency that is registered as such under the Exchange Act and is designated by the Company to act as Depositary for such Registered Securities (or any successor securities clearing agency so registered).

“ Distribution Date ” has the meaning specified in Section 10.4(m) .

“ Dollar ” or “ U.S. $ ” means a dollar or other equivalent unit in such coin or currency of the United States as at the time shall be legal tender for the payment of public and private debts.

“ DTC ” means The Depository Trust Company, a New York corporation.

“ Event of Default ” has the meaning specified in Section 4.1 .

“ Exchange Act ” means the United States Securities Exchange Act of 1934 (or any successor statute), as amended from time to time.

“ Existing Notes ” means the Existing 2002 Senior Subordinated Notes, the Existing 2003 Senior Subordinated Notes, the Existing 2005 Senior Notes, the Existing 2006 Senior Notes, the Existing 2006 Senior Notes, the Existing 2008 Senior Notes and the Existing 2008 13.5% Senior Notes.

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“ Existing 2002 Senior Subordinated Notes ” means the Company’s 5.75% Convertible Senior Subordinated Notes due June 15, 2008, issued under the Existing 2002 Senior Subordinated Notes Indenture.

“ Existing 2002 Senior Subordinated Notes Indenture ” means the Indenture dated as of December 20, 2002, between the Company and the Trustee.

“ Existing 2003 Senior Subordinated Notes ” means the Company’s 4% Convertible Senior Subordinated Notes due July 1, 2010, issued under the Existing 2003 Senior Subordinated Notes Indenture.

“ Existing 2003 Senior Subordinated Notes Indenture ” means the Indenture dated as of June 23, 2003, between the Company and the Trustee.

“ Existing 2005 Senior Notes ” means the Company’s 6.75% Convertible Senior Notes due October 31, 2010, issued under the Existing 2005 Senior Notes Indenture.

“ Existing 2005 Senior Notes Indenture ” means the Indenture dated November 4, 2005 by and between the Company and the Trustee.

“ Existing 2006 Senior Notes ” means the Company’s 7.5% Convertible Senior Notes due 2011, issued under the Existing 2006 Senior Notes Indenture.

“ Existing 2006 Senior Notes Indenture ” means the Indenture dated April 27, 2006 by and between the Company and the Trustee.

“ Existing 2007 Senior Notes ” means the Company’s 5 3/4% Convertible Senior Notes due 2011, issued under the Existing 2007 Senior Notes Indenture.

“ Existing 2007 Senior Notes Indenture ” means the Indenture dated December 12, 2007 by and between the Company and the Trustee.

“ Existing 2008 Senior Notes ” means the Company’s 9% Convertible Senior Notes due 2012, issued under the Existing 2008 Senior Notes Indenture.

“ Existing 2008 Senior Notes Indenture ” means the Indenture dated March 3, 2008 by and between the Company and the Trustee.

“ Existing 2008 13.5% Senior Notes ” means the Company’s 13.5% Convertible Senior Notes due 2014, issued under the Existing 2008 Convertible Senior Notes Indenture.

“ Existing 2008 13.5% Senior Notes Indenture ” means the Indenture dated April 30, 2008 by and between the Company and the Trustee.

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“ Existing Subordinated Notes ” means the Company’s 5.75% Convertible Subordinated Notes due June 15, 2008, issued under the Existing Subordinated Notes Indenture.

“ Existing Subordinated Notes Indenture ” means the Indenture dated as of June 13, 2001, between the Company and the Trustee.

“ Fair Market Value ” with respect to the Common Stock shall be determined by the Company and shall be equal to ninety five percent (95%) of the Volume Weighted Average Price for the five (5) consecutive Trading Days immediately preceding the relevant payment date.

“ GAAP ” means generally accepted accounting principles.

“ Global Security ” means a Registered Security that is registered in the Security Register in the name of a Depositary or a nominee thereof.

“ Holder ” means the Person in whose name the Security is registered in the Security Register.

“ Indebtedness ” means the principal of (and premium, if any) and interest (including all interest accruing subsequent to the commencement of any bankruptcy or similar proceeding, whether or not a claim for post-petition interest is allowable as a claim in any such proceeding) on, and rent payable on or in connection with, and all fees, costs, claims, expenses and other amounts payable in connection with, the following, whether absolute or contingent, secured or unsecured, due or to become due, outstanding on the date of this Indenture or thereafter created, incurred or assumed: (1) all the Company’s indebtedness evidenced by a credit or loan agreement, note, bond, debenture, or other similar instrument whether or not the recourse of the lender is to all of the Company’s assets or only to a portion, (2) all of the Company’s indebtedness, obligations and other liabilities, contingent or otherwise, for borrowed money, including, without limitation, overdrafts, foreign exchange contracts, currency exchange agreements, interest rate protection agreements and any loans or advances from banks, whether or not evidenced by notes or similar instruments, or bonds, debentures, notes or similar instruments, whether or not the recourse of the lender is to all of the Company’s assets or only to a portion thereof, (3) all of the Company’s obligations as lessee under leases required to be capitalized on the balance sheet of the lessee under GAAP, (4) all of the Company’s obligations and other liabilities, contingent or otherwise, under any lease or related document, including a purchase agreement, in connection with the lease of real property or improvements, or any personal property included as part of any such lease, which provides that the Company is contractually obligated to purchase or cause a third party to purchase the leased property and thereby guarantee a residual value of leased property to the lessor and all of the Company’s obligations under such lease or related document to purchase or cause a third party to purchase the leased property, whether or not such lease transaction is characterized as an operating lease or capitalized lease in accordance with generally accepted accounting principles, (5) all of the Company’s obligations under interest rate and currency swaps, caps, floors, collars, hedge agreements, forward contracts, or similar agreements or arrangements, (6) all of the Company’s obligations with respect to letters of credit, bank guarantees, bankers’ acceptances and similar facilities, including related reimbursement obligations, (7) all of the Company’s obligations issued or assumed as the deferred purchase price of property or services (but excluding trade accounts payable and accrued liabilities arising in the ordinary course of business), (8) all of the Company’s obligations of the type referred to in clauses (1) through (7) above of another Person and all

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dividends of another Person, the payment of which, in either case, the Company has assumed or guaranteed or for which the Company is responsible or liable, directly or indirectly, jointly or severally, as obligor, guarantor or otherwise or which is secured by a lien on the Company’s property and (9) renewals, extensions, modifications, replacements, restatements and refundings of, or any indebtedness or obligation issued in exchange for, any such indebtedness or obligation described in clauses (1) through (8) of this definition; provided, however , that Indebtedness shall not include accounts payable or other accrued liabilities or obligations incurred in the ordinary course of business in connection with the obtaining of materials or services and any indebtedness or obligation that the Company may owe to any direct or indirect Subsidiary and obligations owed to a Person specified in clause (11) of the definition of Permitted Lien in connection with the licensing and/or partnering arrangement referred to therein.

“ Indenture ” means this instrument as originally executed or as it may from time to time be supplemented or amended by one or more indentures supplemental hereto entered into pursuant to the applicable provisions hereof, including, for all purposes of this instrument and any such supplemental indenture, the provisions of the Trust Indenture Act that are deemed to be a part of and govern this instrument and any such supplemental indenture, respectively.

“ Interest Payment Date ” means the Stated Maturity of an installment of interest on the Securities.

“ Lien ” means, with respect to any asset, any mortgage, lien, pledge, charge, security interest or encumbrance of any kind with respect to such asset.

“ Maturity ,” when used with respect to any Security, means the date on which the principal of such Security becomes due and payable as therein or herein provided, whether at the Stated Maturity or by declaration of acceleration, conversion, exercise of the repurchase right set forth in Article XII or otherwise.

“ Make-Whole Payment ” has the meaning specified in Article IX .

“ Member ” means any member of, or participant in, the Depositary.

“ New Rights Plan ” has the meaning specified in Section 10.4(d)

“ Non-electing Share ” has the meaning specified in Section 10.11 .

“ Notice of Default ” has the meaning specified in Section 4.1 .

“ Officers’ Certificate ” means a certificate signed by the Chairman of the Board, a Vice Chairman of the Board, the Chief Executive Officer, the President or a Vice President and by the principal financial officer, the Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary of the Company, and delivered to the Trustee.

“ Opinion of Counsel ” means a written opinion of counsel, who may be counsel for or employed by the Company and who shall be acceptable to the Trustee.

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“ Outstanding ,” when used with respect to Securities, means, as of the date of determination, all Securities theretofore authenticated and delivered under this Indenture, except:

(1) securities theretofore cancelled by the Trustee or delivered to the Trustee for cancellation;

(2) securities for the payment of which money in the necessary amount has been theretofore deposited with the Trustee or any Paying Agent (if other than the Company) in trust or set aside and segregated in trust by the Company (if the Company shall act as its own Paying Agent) for the Holders of such Securities; and

(3) securities that have been paid pursuant to Section 2.7 or in exchange for or in lieu of which other Securities have been authenticated and delivered pursuant to this Indenture, other than any such Securities in respect of which there shall have been presented to the Trustee proof satisfactory to it that such Securities are held by a bona fide purchaser in whose hands such Securities are valid obligations of the Company;

provided, however , that in determining whether the Holders of the requisite principal amount of Outstanding Securities are present at a meeting of Holders of Securities for quorum purposes or have given any request, demand, authorization, direction, notice, consent or waiver hereunder, Securities owned by the Company or any other obligor upon the Securities or any Affiliate of the Company or such other obligor shall be disregarded and deemed not to be Outstanding, except that, in determining whether the Trustee shall be protected in relying upon any such determination as to the presence of a quorum or upon any such request, demand, authorization, direction, notice, consent or waiver, only Securities that a Responsible Officer of the Trustee actually knows to be so owned shall be so disregarded. Securities so owned that have been pledged in good faith may be regarded as Outstanding if the pledgee establishes to the satisfaction of the Trustee the pledgee’s right so to act with respect to such Securities and that the pledgee is not the Company or any other obligor upon the Securities or any Affiliate of the Company or such other obligor.

“ Paying Agent ” means any Person authorized by the Company to pay the principal of or interest on any Securities on behalf of the Company and, except as otherwise specifically set forth herein, such term shall include the Company if it shall act as its own Paying Agent. The Company has initially appointed the Trustee as its Paying Agent.

“ Permitted Lien ” means the following types of Liens:

(1) Liens imposed by law for taxes, fees, assessments or other governmental charges or levies that are not yet due and payable or are being contested in good faith by appropriate proceedings as to which the Company or its Subsidiaries shall have set aside on its books such reserves as may be required pursuant to GAAP;

(2) carriers’, warehousemen’s, mechanics’, materialmen’s, repairmen’s, vendors’ or lessors’ Liens (and deposits to obtain the release of such Liens), set-off rights and other like Liens imposed by law (or contract, to the extent that such contractual Liens are similar in nature and scope to Liens imposed by law), in each case arising in the ordinary course of business and securing obligations that either (a) are not overdue by more than sixty (60) days or (ii) are being contested in good faith by appropriate proceedings as to which the Company or its Subsidiaries shall have set aside on its books such reserves as may be required pursuant to GAAP;

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(3) Liens incurred and pledges and deposits made in the ordinary course of business in connection with workers’ compensation, disability or unemployment insurance, old-age pensions, retiree health benefits and other similar plans or programs and other social security laws or regulations;

(4) deposits to secure the performance of bids, trade contracts, leases, statutory obligations, surety and appeal bonds, performance bonds and other obligations of a like nature, in each case in the ordinary course of business;

(5)(a) easements, covenants, conditions, restrictions, zoning restrictions, building codes, land use laws, leases, subleases, licenses, rights of way, minor irregularities in, or lack of, title and similar encumbrances affecting real property, (b) with respect to any lessee’s or licensee’s interest in real or personal property, mortgages, liens, rights and obligations and other encumbrances arising by, through or under any owner, lessor or licensor thereof, with or without the lessee’s or licensee’s consent and (c) leases, licenses, rights and obligations in connection with patents, copyrights, trademarks, tradenames and other intellectual property, in each case that do not secure the payment of borrowed money (other than, with respect to any lessee’s or licensee’s interest in real or personal property, mortgages, liens, rights and obligations and other encumbrances arising by, through or under any owner, lessor or licensor thereof) to the extent, in the case of each of clauses (a), (b) and (c), that the Liens referred to therein do not, in the aggregate, materially detract from the value of the affected property as used by the Company and its Subsidiaries in the ordinary course of business taken as a whole or materially interfere with the ordinary conduct of the business of the Company and its Subsidiaries taken as a whole;

(6) Liens in favor of customs and revenue authorities to secure payment of customs duties in connection with the importation of goods;

(7) any interest or title of a lessor under any capitalized lease obligation; provided, however , that such Liens do not extend to any property or assets which is not leased property subject to such capitalized lease obligation;

(8) Liens securing purchase money indebtedness incurred in the ordinary course of business; provided, however , that (a) such purchase money indebtedness shall not exceed the purchase price or other cost of such property or equipment and shall not be secured by any property or equipment of the Company or any Subsidiary of the Company other than the property and equipment so acquired and (b) the Lien securing such purchase money indebtedness shall be created within ninety (90) days of such acquisition;

(9) Liens securing interest swap obligations which interest swap obligations relate to Indebtedness that is otherwise permitted under the indenture;

(10) Liens securing Indebtedness under currency agreements;

(11) Liens in favor of Strategic Partners in connection with a biopharmaceutical licensing and/or partnering arrangement;

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(12) judgment Liens not giving rise to an Event of Default so long as such Lien is adequately bonded and any appropriate legal proceedings which may have been duly initiated for the review of such judgment shall not have been finally terminated or the period within which such proceedings may be initiated shall not have expired;

(13) Liens upon specific items of inventory or other goods and proceeds of any Person securing such Person’s obligations in respect of bankers’ acceptances issued or created for the account of such Person to facilitate the purchase, shipment or storage of such inventory or other goods;

(14) Liens securing reimbursement obligations with respect to commercial letters of credit which encumber documents and other property relating to such letters of credit and products and proceeds thereof;

(15) banker’s Liens, rights of setoff and similar Liens with respect to cash and Cash Equivalents on deposit in one or more bank accounts in the ordinary course of business; and

(16) Liens arising from filing Uniform Commercial Code financing statements regarding leases.

“ Person ” means a natural person, Corporation, limited liability company, partnership, joint venture, trust, estate, unincorporated organization or government or any agency or political subdivision thereof.

“ Place of Conversion ” has the meaning specified in Section 2.2 .

“ Place of Payment ” has the meaning specified in Section 2.2 .

“ Predecessor Security ” of any particular Security means every previous Security evidencing all or a portion of the same debt as that evidenced by such particular Security; and, for the purposes of this definition, any Security authenticated and delivered under Section 2.7 in exchange for or in lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen Security.

“ Preferred Securities ” means the Series A, Series B, Series C, Series D and Series E Preferred Stock of the Company, and any other issues or series of preferred stock issued by the Company subsequent to the date of this Indenture.

“ Record Date ” means any Regular Record Date or Special Record Date.

“ Record Date Period ” means the period from the close of business of any Regular Record Date next preceding any Interest Payment Date to the opening of business on such Interest Payment Date.

“ Registered Common Stock ” means Common Stock that does not require registration or approval under any federal securities law or, if applicable, the securities laws of any state where a holder is located, before such shares are freely transferable without being subject to transfer restrictions under the Securities Act.

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“ Registered Securities ” has the meaning specified in Section 2.1 .

“ Regular Record Date ” for interest payable in respect of any Registered Security on any Interest Payment Date means the May 1 and the November 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date.

“ Repurchase Date ” has the meaning specified in Section 12.1 .

“ Repurchase Price ” has the meaning specified in Section 12.1 .

“ Responsible Officer ,” when used with respect to the Trustee, means any officer within the Corporate Trust Office, including without limitation any vice president, assistant vice president, assistant treasurer, corporate trust officer or other employee of the Trustee customarily performing functions similar to those performed by any of the above designated officers, and also means, with respect to a particular corporate trust matter, any other officer to whom such matter is referred because of his knowledge and familiarity with the particular subject.

“ Restricted Global Security ” has the meaning specified in Section 2.1 .

“ Secured Indebtedness ” means Indebtedness secured by a Lien other than a Permitted Lien.

“ Securities ” has the meaning ascribed to it in the first paragraph under the caption “Recitals of the Company.”

“ Securities Act ” means the United States Securities Act of 1933 (or any successor statute), as amended from time to time.

“ Security Register ” and “ Security Registrar ” have the respective meanings specified in Section 2.6 .

“ Significant Subsidiary ” means any Subsidiary that would be a “significant subsidiary” as defined in Article 1, Rule 1-02 of Regulation S-X, promulgated pursuant to the Securities Act, as such regulation is in effect on the date hereof.

“ Special Record Date ” for the payment of any Defaulted Interest means a date fixed by the Company pursuant to Section 2.8 .

“ Stated Maturity ,” when used with respect to any Security or any installment of interest thereon, means the date specified in such Security as the fixed date on which the principal of such Security or such installment of interest is due and payable.

“ Strategic Partner ” means (i) a pharmaceutical or biotechnology company with book equity of at least U.S. $200,000,000, (ii) a pharmaceutical or biotechnology company with sales of at least U.S. $150,000,000, or (iii) a publicly traded, or division or subdivision of a publicly traded, pharmaceutical or biotechnology company with market capitalization in excess of U.S. $200,000,000.

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“ Subsidiary ” means a Person more than fifty percent (50%) of the outstanding voting stock of which is owned, directly or indirectly, by the Company or by one or more other Subsidiaries, or by the Company and one or more other Subsidiaries. For the purposes of this definition, “voting stock” means stock or other similar interests in the Person that ordinarily has or have voting power for the election of directors or Persons performing similar functions, whether at all times or only so long as no senior class of stock or other interests has or have such voting power by reason of any contingency.

“ Successor Security ” of any particular Security means every Security issued after, and evidencing all or a portion of the same debt as that evidenced by, such particular Security; and, for the purposes of this definition, any Security authenticated and delivered under Section 2.7 in exchange for or in lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen Security.

“ Trading Day ” means: (1) if the Common Stock is listed or admitted for trading on any national securities exchange, days on which such national securities exchange is open for business; (2) if the Common Stock is quoted on the Nasdaq Global Market or any other system of automated dissemination of quotations of securities prices, days on which trades may be effected through such system; or (3) if the Common Stock is not listed or admitted for trading on any national securities exchange or quoted on the Nasdaq Global Market or any other system of automated dissemination of quotation of securities prices, days on which the Common Stock is traded regular way in the over-the-counter market and for which a closing bid and a closing asked price for the Common Stock are available.

“ Trust Indenture Act ” means the Trust Indenture Act of 1939 as in force at the date as of which this instrument was executed; provided, however , that in the event the Trust Indenture Act of 1939 is amended after such date, “Trust Indenture Act” means, to the extent required by any such amendment, the Trust Indenture Act of 1939 as so amended.

“ Trustee ” means the Person named as the “Trustee” in the first paragraph of this instrument until a successor Trustee shall have become such pursuant to the applicable provisions of this Indenture, and thereafter “Trustee” shall mean such successor Trustee.

“ United States ” means the United States of America (including the several States and the District of Columbia), its territories, its possessions and other areas subject to its jurisdiction (its “possessions” including Puerto Rico, the United States Virgin Islands, Guam, American Samoa, Wake Island and the Northern Mariana Islands).

“ Vice President ,” when used with respect to the Company, means any vice president, whether or not designated by a number or a word or words added before or after the title “vice president.”

“ Volume Weighted Average Price ” means, with respect to the Common Stock of the Company, for any day the volume weighted average price per share of Common Stock as displayed on Bloomberg on the Nasdaq Global Market from 9:30 a.m. to 4:00 p.m. (New York City time) on that day (or if such volume weighted average price is not available, the market value of one share on such day as the Company determines in good faith using a volume weighted method).

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SECTION 1.2 Compliance Certificates and Opinions .

Upon any application or request by the Company to the Trustee to take any action under any provision of this Indenture, the Company shall furnish to the Trustee an Officers’ Certificate stating that all conditions precedent, if any, provided for in this Indenture relating to the proposed action have been complied with and, if required by the Trust Indenture Act, an Opinion of Counsel stating that in the opinion of such counsel all such conditions precedent, if any, have been complied with, except that in the case of any such application or request as to which the furnishing of such documents is specifically required by any provision of this Indenture relating to such particular application or request, no additional certificate or opinion need be furnished. Every certificate or opinion with respect to compliance with a condition or covenant provided for in this Indenture shall include:

(a) a statement that each individual signing such certificate or opinion has read such covenant or condition and the definitions herein relating thereto;

(b) a brief statement as to the nature and scope of the examination or investigation upon which the statements or opinions contained in such certificate or opinion are based;

(c) a statement that, in the opinion of such individual, he has made such examination or investigation as is necessary to enable him to express an informed opinion as to whether or not such covenant or condition has been complied with; and

(d) a statement as to whether, in the opinion of each such individual, such condition or covenant has been complied with; provided, however , with respect to matters of fact, an Opinion of Counsel may rely on an Officers’ Certificate or certificates of public officials.

SECTION 1.3 Form of Documents Delivered to the Trustee .

In any case where several matters are required to be certified by, or covered by an opinion of, any specified Person, it is not necessary that all such matters be certified by, or covered by the opinion of, only one such Person, or that they be so certified or covered by only one document, but one such Person may certify or give an opinion with respect to some matters and one or more other such Persons as to other matters, and any such Person may certify or give an opinion as to such matters in one or several documents.

Any certificate or opinion of an officer of the Company may be based, insofar as it relates to legal matters, upon a certificate or opinion of, or representations by, counsel, unless such officer knows, or in the exercise of reasonable care should know, that the certificate or opinion or representations with respect to the matters upon which such certificate or opinion is based are erroneous. Any such certificate or opinion of counsel may be based, insofar as it relates to factual matters, upon a certificate or opinion of, or representations by, an officer or officers of the Company or any other Person stating that the information with respect to such factual matters is in the possession of the Company or such other Person, unless such counsel knows, or in the exercise of reasonable care should know, that the certificate or opinion or representations with respect to such matters are erroneous.

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Where any Person is required to make, give or execute two or more applications, requests, consents, certificates, statements, opinions or other instruments under this Indenture, they may, but need not, be consolidated and form one instrument.

SECTION 1.4 Acts of Holders of Securities .

(a) Any request, demand, authorization, direction, notice, consent, waiver or other action provided or permitted by this Indenture to be given or taken by Holders of Securities may be embodied in and evidenced by one or more instruments of substantially similar tenor signed by such Holders in person or by an agent or proxy duly appointed in writing by such Holders. Such action shall become effective when such instrument or instruments is delivered to the Trustee and, where it is hereby expressly required, to the Company. The Trustee shall promptly deliver to the Company copies of all such instruments delivered to the Trustee. Such instrument or instruments (and the action embodied therein and evidenced thereby) are herein sometimes referred to as the “ Act ” of the Holders of Securities signing such instrument or instruments. Proof of execution of any such instrument or of a writing appointing any such agent or proxy, or of the holding by any Person of a Security, shall be sufficient for any purpose of this Indenture and (subject to Section 5.1 ) conclusive in favor of the Trustee and the Company if made in the manner provided in this Section 1.4 .

(b) The fact and date of the execution by any Person of any such instrument or writing may be proved by the affidavit of a witness of such execution or by a certificate of a notary public or other officer authorized by law to take acknowledgments of deeds, certifying that the individual signing such instrument or writing acknowledged to him the execution thereof. Where such execution is by a signer acting in a capacity other than his individual capacity, such certificate or affidavit shall also constitute sufficient proof of his authority.

(c) The principal amount and serial number of any Registered Security held by any Person, and the date of his holding the same, shall be proved by the Security Register.

(d) The fact and date of execution of any such instrument or writing and the authority of the Person executing the same may also be proved in any other manner that the Trustee deems sufficient; and the Trustee may in any instance require further proof with respect to any of the matters referred to in this Section 1.4 .

(e) The Company may set any day as the record date for the purpose of determining the Holders entitled to give or take any request, demand, authorization, direction, notice, consent, waiver or other action, or to vote on any action, authorized or permitted by this Indenture to be given or taken by Holders. Promptly and in any case not later than ten (10) days after setting a record date, the Company shall notify the Trustee and the Holders of such record date. If not set by the Company prior to the first solicitation of a Holder made by any Person in respect of any such action, or, in the case of any such vote, prior to such vote, the record date for any such action or vote shall be the thirtieth (30th) day (or, if later, the date of the most recent list of Holders required to be provided pursuant to Section 13.1 ) prior to such first solicitation or vote, as the case may be. With regard to any record date, the Holders on such date (or their duly appointed agents or proxies), and only such Persons, shall be entitled to give or take, or vote on, the relevant action, whether or not such Holders remain Holders after such record date. Notwithstanding the foregoing, the Company shall not set a record date for, and the provisions of this paragraph shall not apply with respect to, any notice, declaration or direction referred to in the next paragraph.

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Upon receipt by the Trustee from any Holder of (1) any Notice of Default or breach referred to in Section 4.1(d) , if such default or breach has occurred and is continuing and the Trustee shall not have given such a notice to the Company, (2) any declaration of acceleration referred to in Section 4.2 , if an Event of Default has occurred and is continuing and the Trustee shall not have given such a declaration to the Company, or (3) any direction referred to in Section 4.12 , if the Trustee shall not have taken the action specified in such direction, then, with respect to clauses (2) and (3), a record date shall automatically and without any action by the Company or the Trustee be set for determining the Holders entitled to join in such declaration or direction, which record date shall be the close of business on the tenth (10th) day (or, if such day is not a Business Day, the next succeeding Business Day) following the day on which the Trustee receives such declaration or direction, and, with respect to clause (1), the Trustee may set any day as a record date for the purpose of determining the Holders entitled to join in such Notice of Default. Promptly after such receipt by the Trustee of any such declaration or direction referred to in clause (2) or (3), and promptly after setting any record date with respect to clause (1), and as soon as practicable thereafter, the Trustee shall notify the Company and the Holders of any such record date so fixed. The Holders on such record date (or their duly appointed agents or proxies), and only such Persons, shall be entitled to join in such notice, declaration or direction, whether or not such Holders remain Holders after such record date; provided, however , that, unless such notice, declaration or direction shall have become effective by virtue of Holders of the requisite principal amount of Securities on such record date (or their duly appointed agents or proxies) having joined therein on or prior to the ninetieth (90th) day after such record date, such notice, declaration or direction shall automatically and without any action by any Person be cancelled and of no further effect. Nothing in this paragraph shall be construed to prevent a Holder (or a duly appointed agent or proxy thereof) from giving, before or after the expiration of such 90-day period, a notice, declaration or direction contrary to or different from, or, after the expiration of such period, identical to, the notice, declaration or direction to which such record date relates, in which event a new record date in respect thereof shall be set pursuant to this paragraph. In addition, nothing in this paragraph shall be construed to render ineffective any notice, declaration or direction of the type referred to in this paragraph given at any time to the Trustee and the Company by Holders (or their duly appointed agents or proxies) of the requisite principal amount of Securities on the date such notice, declaration or direction is so given.

(f) Except as provided in Sections 4.2 and 4.13 , any request, demand, authorization, direction, notice, consent, election, waiver or other Act of the Holder of any Security shall bind every future Holder of the same Security and the Holder of every Security issued upon the registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered to be done by the Trustee or the Company in reliance thereon, whether or not notation of such action is made upon such Security.

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SECTION 1.5 Notices, Etc., to Trustee and Company .

Any request, demand, authorization, direction, notice, consent, election, waiver or other Act of Holders of Securities or other document provided or permitted by this Indenture to be made upon, given or furnished to, or filed with:

(a) the Trustee by any Holder of Securities or by the Company shall be sufficient for every purpose hereunder if made, given, furnished or filed in writing to or with the Trustee and received at the Corporate Trust Office, Attention: Corporate Trust Services (Cell Therapeutics, Inc. – 15% Convertible Senior Notes Due 2011), and shall be deemed given when received; or

(b) the Company by the Trustee or by any Holder of Securities shall be sufficient for every purpose hereunder (unless otherwise herein expressly provided) if in writing, mailed, first-class postage prepaid, or telecopied and confirmed by mail, first-class postage prepaid, or delivered by hand or overnight courier, addressed to the Company at 501 Elliott Avenue West, Suite 400, Seattle, Washington 98119, Attention: Louis A. Bianco (telecopy no.: (206) 284-6206), or at any other address previously furnished in writing to the Trustee by the Company, and shall be deemed given when received.

Any request, demand, authorization, direction, notice, consent, election or waiver required or permitted under this Indenture shall be in the English language, except that any published notice may be in an official language of the country of publication.

SECTION 1.6 Notice to Holders of Securities; Waiver .

Except as otherwise expressly provided herein, where this Indenture provides for notice to Holders of Securities of any event, such notice shall be sufficiently given to Holders if in writing and mailed, first-class postage prepaid, to each Holder of a Security affected by such event, at the address of such Holder as it appears in the Security Register, not earlier than the earliest date and not later than the latest date prescribed for the giving of such notice.

Neither the failure to mail such notice, nor any defect in any notice so mailed, to any particular Holder of a Registered Security shall affect the sufficiency of such notice with respect to other Holders of Registered Securities. In case by reason of the suspension of regular mail service or by reason of any other cause it shall be impracticable to give such notice by mail, then such notification to Holders of Registered Securities as shall be made with the approval of the Trustee, which approval shall not be unreasonably withheld or delayed, shall constitute a sufficient notification to such Holders for every purpose hereunder.

Such notice shall be deemed to have been given when such notice is mailed.

Where this Indenture provides for notice in any manner, such notice may be waived in writing by the Person entitled to receive such notice, either before or after the event, and such waiver shall be the equivalent of such notice. Waivers of notice by Holders of Securities shall be filed with the Trustee, but such filing shall not be a condition precedent to the validity of any action taken in reliance upon such waiver.

SECTION 1.7 Effect of Headings and Table of Contents .

The Article and Section headings herein and the Table of Contents are for convenience only and shall not affect the construction hereof.

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SECTION 1.8 Successors and Assigns .

All covenants and agreements in this Indenture by the Company and by the Trustee shall bind its successors and assigns, whether so expressed or not.

SECTION 1.9 Separability Clause .

In case any provision in this Indenture or the Securities shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 1.10 Benefits of Indenture .

Nothing in this Indenture or in the Securities, express or implied, shall give to any Person, other than the parties hereto and their successors and assigns hereunder and the Holders of Securities, any benefit or legal or equitable right, remedy or claim under this Indenture.

SECTION 1.11 Governing Law .

THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, THE UNITED STATES OF AMERICA, INCLUDING, WITHOUT LIMITATION, THE NEW YORK GENERAL OBLIGATIONS LAW §5-1401.

SECTION 1.12 Legal Holidays .

In any case where any Interest Payment Date, Repurchase Date or Stated Maturity of any Security or the last day on which a Holder of a Security has a right to convert his Security shall not be a Business Day at a Place of Payment or Place of Conversion, as the case may be, then (notwithstanding any other provision of this Indenture or of the Securities) payment of principal of, premium, if any, or interest on, or the payment of the Repurchase Price (whether the same is payable in cash or in shares of Common Stock) with respect to, or delivery for conversion of, such Security need not be made at such Place of Payment or Place of Conversion, as the case may be, on or by such day, but may be made on or by the next succeeding Business Day at such Place of Payment or Place of Conversion, as the case may be, with the same force and effect as if made on the Interest Payment Date or Repurchase Date, or at the Stated Maturity or by such last day for conversion; provided, however , that in the case that payment is made on such succeeding Business Day, no interest shall accrue on the amount so payable for the period from and after such Interest Payment Date, Repurchase Date, Stated Maturity or last day for conversion, as the case may be.

SECTION 1.13 Conflict with Trust Indenture Act .

If any provision hereof limits, qualifies or conflicts with a provision of the Trust Indenture Act that is required under such act to be a part of and govern this Indenture, the latter provision shall control. If any provision of this Indenture modifies or excludes any provision of the Trust Indenture Act that may be so modified or excluded, the latter provision shall be deemed to apply to this Indenture as so modified or to be excluded, as the case may be. Until such time as this Indenture shall be qualified under the Trust Indenture Act, this Indenture, the Company and the Trustee shall be deemed for all purposes hereof to be subject to and governed by the Trust Indenture Act to the same extent as would be the case if this Indenture were so qualified on the date hereof.

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SECTION 1.14 Counterparts .

This instrument may be executed in any number of counterparts, each of which so executed shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

ARTICLE II

THE SECURITIES

SECTION 2.1 Form Generally .

The Securities and the Trustee’s certificate of authentication shall be in substantially the form set forth in Exhibit A hereto, which Exhibit is incorporated into this Indenture, with such appropriate insertions, omissions, substitutions and other variations as are required or permitted by this Indenture, and may have such letters, numbers or other marks of identification and such legends or endorsements placed thereon as may be required to comply with the rules of any securities exchange or the Internal Revenue Code of l986, as amended, and regulations thereunder (the “ Code ”), or as may, consistently herewith, be determined by the officers executing such Securities, as evidenced by their execution thereof. All Securities shall be issued in registered form, as opposed to bearer form, and shall sometimes be referred to as the “ Registered Securities .”

The Securities shall be printed, lithographed, typewritten or engraved or produced by any combination of these methods on steel engraved borders, if so required by any securities exchange upon which the Securities may be listed, or may be produced in any other manner permitted by the rules of any such securities exchange, or, if the Securities are not listed on a securities exchange, in any other manner approved by the Company, all as determined by the officers executing such Securities, as evidenced by their execution thereof.

Upon their original issuance, Securities shall be issued in the form of one or more Global Securities without interest coupons and shall be registered in the name of DTC, as Depositary, or its nominee and deposited with the Trustee, as custodian for DTC, for credit by DTC to the respective accounts of beneficial owners of the Securities represented thereby (or such other accounts as they may direct). Such Global Security, together with its Successor Securities that are Global Securities, are collectively herein called the “ Restricted Global Security .”

SECTION 2.2 Title and Terms .

The aggregate principal amount of Securities that may be authenticated and delivered under this Indenture is limited to U.S. $23,000,000, except for Securities authenticated and delivered in exchange for, or in lieu of, other Securities pursuant to Section 2.5 , 2.6 , 2.7 , 7.5 , 10.2 or 12.2(e) .

The Securities shall be known and designated as the “15% Convertible Senior Notes due 2011” of the Company. Their Stated Maturity shall be June 12, 2011 and they shall bear interest on their principal amount from June 12, 2008, payable semiannually in arrears on May 15 and November 15 in each year, commencing November 15, 2008, at the rate of 15% per annum until the principal thereof is due and at the rate then in effect on any overdue principal and, to the extent permitted by law, on any overdue interest; provided, however , that payments shall only be made on Business Days as provided in Section 1.12 .

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The principal of, premium, if any, interest and Make-Whole Payment on the Securities shall be payable as provided in the form of Securities attached hereto as Exhibit A , and the Repurchase Price shall be payable at such places as are identified in the Company Notice given pursuant to Section 12.2 (any city in which any Paying Agent is located being herein called a “ Place of Payment ”).

The Securities shall be convertible as provided in Article X (any city in which any Conversion Agent is located being herein called a “ Place of Conversion ”).

The Securities shall be subject to repurchase by the Company at the option of the Holders as provided in Article XII .

SECTION 2.3 Denominations .

The Securities shall be issuable only in registered form, without interest coupons, in any denomination.

SECTION 2.4 Execution, Authentication, Delivery and Dating .

The Securities shall be executed on behalf of the Company by its Chairman of the Board, its Vice Chairman of the Board, its Chief Executive Officer, its President, one of its Vice Presidents, its Chief Financial Officer, its Treasurer or its Controller and attested by its Secretary or one of its Assistant Secretaries. Any such signature may be manual or facsimile.

Securities bearing the manual or facsimile signature of individuals who were at any time the proper officers of the Company shall bind the Company, notwithstanding that such individuals or any of them have ceased to hold such offices prior to the authentication and delivery of such Securities or did not hold such offices at the date of such Securities.

At any time and from time to time after the execution and delivery of this Indenture, the Company may deliver Securities executed by the Company to the Trustee or to its order for authentication, together with a Company Order for the authentication and delivery of such Securities, and the Trustee in accordance with such Company Order shall authenticate and make available for delivery such Securities as provided in this Indenture and not otherwise.

Each Security shall be dated the date of its authentication.

No Security shall be entitled to any benefit under this Indenture or be valid or obligatory for any purpose unless there appears on such Security a certificate of authentication substantially in the form provided for herein executed by the Trustee by manual signature of an authorized signatory, and such certificate upon any Security shall be conclusive evidence, and the only evidence, that such Security has been duly authenticated and delivered hereunder.

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SECTION 2.5 Global Securities .

Each Global Security authenticated under this Indenture shall be registered in the name of the Depositary designated by the Company for such Global Security or a nominee thereof and delivered to such Depositary or a nominee thereof or custodian therefor, and each such Global Security shall constitute a single Security for all purposes of this Indenture.

Notwithstanding any other provision in this Indenture, no Global Security may be exchanged in whole or in part for Securities registered, and no transfer of a Global Security in whole or in part may be registered, in the name of any Person other than the Depositary for such Global Security or a nominee thereof unless (A) such Depositary (i) has notified the Company that it is unwilling or unable to continue as Depositary for such Global Security or (ii) has ceased to be a clearing agency registered as such under the Exchange Act or announces an intention permanently to cease business or does in fact do so or (B) there shall have occurred and be continuing an Event of Default with respect to such Global Security.

If any Global Security is to be exchanged for other Securities or cancelled in whole, it shall be surrendered by or on behalf of the Depositary or its nominee to the Trustee, as Security Registrar, for exchange or cancellation, as provided in this Article II . If any Global Security is to be exchanged for other Securities or cancelled in part, or if another Security is to be exchanged in whole or in part for a beneficial interest in any Global Security, in each case, as provided in Section 2.6 , then either (A) such Global Security shall be so surrendered for exchange or cancellation, as provided in this Article II, or (B) the principal amount thereof shall be reduced or increased by an amount equal to the portion thereof to be so exchanged or cancelled or equal to the principal amount of such other Security to be so exchanged for a beneficial interest therein, as the case may be, by means of an appropriate adjustment made on the records of the Trustee, as Security Registrar, whereupon the Trustee, in accordance with the Applicable Procedures, shall instruct the Depositary or its authorized representative to make a corresponding adjustment to its records. Upon any such surrender or adjustment of a Global Security, the Trustee shall, subject to Section 2.6(c) and as otherwise provided in this Article II, authenticate and make available for delivery any Securities issuable in exchange for such Global Security (or any portion thereof) to or upon the order of, and registered in such names as may be directed by, the Depositary or its authorized representative. Upon the request of the Trustee in connection with the occurrence of any of the events specified in the preceding paragraph, the Company shall promptly make available to the Trustee a reasonable supply of Securities that are not in the form of Global Securities. The Trustee shall be entitled to rely upon any order, direction or request of the Depositary or its authorized representative which is given or made pursuant to this Article II.

Every Security authenticated and delivered upon registration of transfer of, or in exchange for or in lieu of, a Global Security or any portion thereof, whether pursuant to this Article II or otherwise, shall be authenticated and delivered in the form of, and shall be, a registered Global Security, unless such Security is registered in the name of a Person other than the Depositary for such Global Security or a nominee thereof, in which case such Registered Security shall be authenticated and delivered in definitive, fully registered form, without interest coupons.

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The Depositary or its nominee, as registered owner of a Global Security, shall be the Holder of such Global Security for all purposes under the Indenture and the Registered Securities, and owners of beneficial interests in a Global Security shall hold such interests pursuant to the Applicable Procedures. Accordingly, any such owner’s beneficial interest in a Global Security shall be shown only on, and the transfer of such interest shall be effected only through, records maintained by the Depositary or its nominee or its Agent Members, and such owners of beneficial interests in a Global Security shall not be considered the owners or holders thereof.

SECTION 2.6 Registration, Registration of Transfer and Exchange .

(a) The Company shall cause to be kept at the Corporate Trust Office a register (the register maintained in such office and in any other office or agency of the Company designated pursuant to Section 8.2 being herein sometimes collectively referred to as the “ Security Register ”) in which, subject to such reasonable regulations as it may prescribe, the Company shall provide for the registration of Registered Securities and of transfers of Registered Securities. The Trustee is hereby appointed “ Security Registrar ” for the purpose of registering Registered Securities and transfers and exchanges of Registered Securities as herein provided.

Upon surrender for registration of transfer of any Security at an office or agency of the Company designated pursuant to Section 8.2 for such purpose, the Company shall execute, and the Trustee shall authenticate and deliver, in the name of the designated transferee or transferees, one or more new Securities of any authorized denominations and of a like aggregate principal amount and bearing such restrictive legends as may be required by this Indenture.

At the option of the Holder, and subject to the other provisions of this Section 2.6 , Securities may be exchanged for other Securities of any authorized denomination and of a like aggregate principal amount, upon surrender of the Securities to be exchanged at any such office or agency. Whenever any Securities are so surrendered for exchange, and subject to the other provisions of this Section 2.6 , the Company shall execute, and the Trustee shall authenticate and make available for delivery, the Securities the Holder making the exchange is entitled to receive. Every Security presented or surrendered for registration of transfer or for exchange shall (if so required by the Company or the Security Registrar) be duly endorsed, or be accompanied by a written instrument of transfer in form satisfactory to the Company and the Security Registrar, duly executed by the Holder thereof or his attorney duly authorized in writing.

All Securities issued upon any registration of transfer or exchange of Securities shall be the valid obligations of the Company, evidencing the same debt, subject to the other provisions of this Section 2.6 , and entitled to the same benefits under this Indenture, as the Securities surrendered upon such registration of transfer or exchange.

No service charge shall be made to a Holder for any registration of transfer or exchange of Securities except as provided in Section 2.7 , but the Company may require payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in connection with any registration of transfer or exchange of Securities, other than exchanges pursuant to Section 2.5 , 7.5 , 10.2 or 12.2(e) (other than where the shares of Common Stock are to be issued or delivered in a name other than that of the Holder of the Security) not involving any transfer and other than any stamp and other duties, if any, that may be imposed in connection with any such transfer or exchange by the United States or any political subdivision thereof or therein, which shall be paid by the Company.

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(b) Neither the Trustee, the Paying Agent nor any of their agents shall (1) have any duty to monitor compliance with or with respect to any federal or state or other securities or tax laws or (2) have any duty to obtain documentation on any transfers or exchanges other than as specifically required hereunder.

SECTION 2.7 Mutilated, Destroyed, Lost or Stolen Securities .

If any mutilated Security is surrendered to the Trustee, the Company shall execute and the Trustee shall authenticate and make available for delivery in exchange therefor a new Security of like tenor and principal amount and bearing a number not contemporaneously outstanding.

If there be delivered to the Company and to the Trustee:

(a) evidence to their satisfaction of the destruction, loss or theft of any Security, and

(b) such security or indemnity as may be satisfactory to the Company and the Trustee to save each of them and any agent of either of them harmless, then, in the absence of actual notice to the Company or the Trustee that such Security has been acquired by a bona fide purchaser, the Company shall execute and the Trustee shall authenticate and make available for delivery, in lieu of any such destroyed, lost or stolen Security, a new Security of like tenor and principal amount and bearing a number not contemporaneously outstanding.

In case any such mutilated, destroyed, lost or stolen Security has become or is about to become due and payable, the Company in its discretion, but subject to any conversion rights, may, instead of issuing a new Security, pay such Security, upon satisfaction of the conditions set forth in the preceding paragraph.

Upon the issuance of any new Security under this Section 2.7 , the Company may require the payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in relation thereto (other than any stamp and other duties, if any, that may be imposed in connection therewith by the United States or any political subdivision thereof or therein, which shall be paid by the Company) and any other expenses (including the fees and expenses of the Trustee) connected therewith.

Every new Security issued pursuant to this Section 2.7 in lieu of any mutilated, destroyed, lost or stolen Security shall constitute an original additional contractual obligation of the Company, whether or not the mutilated, destroyed, lost or stolen Security shall be at any time enforceable by anyone, and such new Security shall be entitled to all the benefits of this Indenture equally and proportionately with any and all other Securities duly issued hereunder.

The provisions of this Section 2.7 are exclusive and shall preclude (to the extent lawful) all other rights and remedies of any Holder with respect to the replacement or payment of mutilated, destroyed, lost or stolen Securities.

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SECTION 2.8 Payment of Interest; Interest Rights Preserved .

Interest on any Security that is payable, and is punctually paid or duly provided for, on any Interest Payment Date shall be paid, at the option of the Company, in immediately available funds, Registered Common Stock or some combination of immediately available funds or Registered Common Stock as provided in the Security to the Person in whose name that Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest. For the purpose of any interest payment in Registered Common Stock, whether in whole or in part, such payment will have a Fair Market Value equal to the interest payment due on the Interest Payment Date and shall be subject to the restrictions on issuance as set forth in Section 8.7 herein.

Any interest on any Security that is payable, but is not punctually paid or duly provided for, on any Interest Payment Date (“ Defaulted Interest ”) shall forthwith cease to be payable to the Holder on the relevant Regular Record Date by virtue of having been such Holder, and such Defaulted Interest may be paid by the Company, at its election in each case, as provided in clause (a) or (b) below:

(a) The Company may elect to make payment of any Defaulted Interest to the Persons in whose names the Securities (or their respective Predecessor Securities) are registered at the close of business on a Special Record Date for the payment of such Defaulted Interest, which shall be fixed in the following manner. The Company shall notify the Trustee in writing of the amount of Defaulted Interest proposed to be paid on each Security, the date of the proposed payment and the Special Record Date, and at the same time the Company shall deposit with the Trustee an amount of money equal to the aggregate amount proposed to be paid in respect of such Defaulted Interest or shall make arrangements satisfactory to the Trustee for such deposit prior to the date of the proposed payment, such money when deposited to be held in trust for the benefit of the Persons entitled to such Defaulted Interest as provided in this clause. The Special Record Date for the payment of such Defaulted Interest shall be not more than fifteen (15) days and not less than ten (10) days prior to the date of the proposed payment and not less than fifteen (15) days after the receipt by the Trustee of the notice of the proposed payment. The Trustee, in the name and at the expense of the Company, shall cause notice of the proposed payment of such Defaulted Interest and the Special Record Date therefor to be mailed, first-class postage prepaid, to each Holder at such Holder’s address as it appears in the Security Register, not less than ten (10) days prior to such Special Record Date. Notice of the proposed payment of such Defaulted Interest and the Special Record Date therefor having been so mailed, such Defaulted Interest shall be paid to the Persons in whose names the Securities (or their respective Predecessor Securities) are registered at the close of business on such Special Record Date and shall no longer be payable pursuant to the following clause (b).

(b) The Company may make payment of any Defaulted Interest in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities may be listed, and upon such notice as may be required by such exchange, if, after notice given by the Company to the Trustee of the proposed payment pursuant to this clause, such manner of payment shall be deemed practicable by the Trustee.

Subject to the foregoing provisions of this Section 2.8 and Section 2.6 , each Security delivered under this Indenture upon registration of transfer of or in exchange for or in lieu of any other Security shall carry the rights to interest accrued and unpaid, and to accrue, that were carried by such other Security.

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Interest on any Security that is converted in accordance with Section 10.2 during a Record Date Period shall be payable in accordance with the provisions of Section 10.2 .

SECTION 2.9 Persons Deemed Owners .

Prior to due presentment of a Security for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name such Security is registered as the owner of such Security for the purpose of receiving payment of principal of, premium, if any, and (subject to Section 2.8 ) interest on such Security and for all other purposes whatsoever, whether or not such Security be overdue, and neither the Company, the Trustee nor any agent of the Company or the Trustee shall be affected by notice to the contrary.

SECTION 2.10 Cancellation .

All Securities surrendered for payment, repurchase, registration of transfer or exchange or conversion shall, if surrendered to any Person other than the Trustee, be delivered to the Trustee. All Securities so delivered to the Trustee shall be cancelled promptly by the Trustee. No Securities shall be authenticated in lieu of or in exchange for any Securities cancelled as provided in this Section 2.10 . The Trustee shall dispose of all cancelled Securities in accordance with applicable law and its customary practices in effect from time to time.

SECTION 2.11 Computation of Interest .

Interest on the Securities shall be computed on the basis of a 360-day year of twelve (12) 30-day months.

SECTION 2.12 CUSIP Numbers .

The Company in issuing Securities shall obtain and use “CUSIP” numbers (if then generally in use) in addition to serial numbers and the Trustee shall use such CUSIP numbers in addition to serial numbers in notices of repurchase as a convenience to Holders; provided, however , that any such notice may state that no representation is made as to the correctness of such CUSIP numbers either as printed on the Securities or as contained in any notice of a repurchase and that reliance may be placed only on the serial or other identification numbers printed on the Securities, and any such repurchase shall not be affected by any defect in or omission of such CUSIP numbers. The Company shall promptly notify the Trustee in writing of any change in any such CUSIP number.

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ARTICLE III

SATISFACTION AND DISCHARGE

SECTION 3.1 Satisfaction and Discharge of Indenture .

This Indenture shall upon Company Request cease to be of further effect (except as to any surviving rights of conversion, or registration of transfer or exchange, or replacement of Securities herein expressly provided for and the Company’s obligations to the Trustee pursuant to Section 5.7 ), and the Trustee, at the expense of the Company, shall execute proper instruments in form and substance satisfactory to the Trustee acknowledging satisfaction and discharge of this Indenture, when:

(a) either:

(1) all Securities theretofore authenticated and delivered (other than (A) Securities that have been destroyed, lost or stolen and that have been replaced or paid as provided in Section 2.7 and (B) Securities for whose payment money has theretofore been deposited in trust or segregated and held in trust by the Company and thereafter repaid to the Company or discharged from such trust, as provided in Section 8.3 ) have been delivered to the Trustee for cancellation; or

(2) all such Securities not theretofore delivered to the Trustee or its agent for cancellation (other than Securities referred to in clauses (A) and (B) of clause (a)(1) above):

(i) have become due and payable; or

(ii) will have become due and payable at their Stated Maturity within one (1) year;

and the Company, in the case of clause (i) or (ii) above, has deposited or caused to be deposited with the Trustee as trust funds (immediately available to the Holders in the case of clause (i) above) an amount sufficient to pay and discharge the entire principal, premium, if any, and interest on such Securities not theretofore delivered to the Trustee for cancellation, to the date of such deposit (in the case of Securities that have become due and payable) or to the Stated Maturity; and

(b) the Company has paid or caused to be paid all other sums payable hereunder by the Company; and

(c) the Company has delivered to the Trustee an Officers’ Certificate stating that all conditions precedent herein provided for relating to the satisfaction and discharge of this Indenture have been complied with.

Notwithstanding the satisfaction and discharge of this Indenture, the obligations of the Company to the Trustee under Section 5.7 , the obligations of the Company to any Authenticating Agent under Section 5.12 , the obligations of the Trustee under Section 3.2 and the last paragraph of Section 8.3 , if money shall have been deposited with the Trustee pursuant to clause (a)(2) of this Section 3.1 , the obligations of the Company and the Trustee and the rights of the Holders under Article IV and the obligations of the Company and the Trustee under Section 2.6 and Article X shall survive. Funds held in trust pursuant to this Section 3.1 are not subject to the provisions of Article XI .

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SECTION 3.2 Application of Trust Money .

Subject to the provisions of the last paragraph of Section 8.3 , all money deposited with the Trustee pursuant to Section 3.1 shall be held in trust and applied by it, in accordance with the provisions of the Securities and this Indenture, to the payment, either directly or through any Paying Agent (including the Company acting as its own Paying Agent), to the Persons entitled thereto, of the principal, premium, if any, interest and Make-Whole Payment, if any, for whose payment such money has been deposited with the Trustee.

All moneys deposited with the Trustee pursuant to Section 3.1 (and held by it or any Paying Agent) for the payment of Securities subsequently converted shall be returned to the Company upon Company Request.

ARTICLE IV

REMEDIES

SECTION 4.1 Events of Default .

“ Event of Default ,” wherever used herein, means any one of the following events (whatever the reason for such Event of Default and whether it shall be occasioned by the provisions of Article XI or be voluntary or involuntary or be effected by operation of law or pursuant to any judgment, decree or order of any court or any order, rule or regulation of any administrative or governmental body):

(a) default in the payment of the principal of or premium, if any, on any Security at its Maturity; or

(b) default in the payment of any interest if any, upon any Security when it becomes due and payable, or in the payment of the Make-Whole Amount when due, and continuance of such default for a period of thirty (30) days;

(c) failure by the Company to obtain Authorized Share Approval by July 4, 2008;

(d) failure by the Company to give the Company Notice in accordance with Section 12.2 ; or

(e) default in the performance, or breach, of any covenant of the Company or any Subsidiary in this Indenture (other than a covenant of default in the performance or breach of which is specifically dealt with elsewhere in this Section 4.1 ), and continuance of such default or breach for a period of thirty (30) days after there has been given, by registered or certified mail, to the Company by the Trustee or to the Company and the Trustee by the Holders of at least $1,000,000 in aggregate principal amount of the Outstanding Securities, a written notice specifying such default or breach and requiring it to be remedied and stating that such notice is a “ Notice of Default ” hereunder; or

(f) default in the payment when due of the principal of any indebtedness under any bond, debenture, note or other evidence of indebtedness for money borrowed by the Company or any Significant Subsidiary in excess of U.S. $10,000,000, whether such indebtedness now exists or shall hereafter be created, if the indebtedness is not discharged and such default continues for a period of thirty (30) days or more, or if such indebtedness has been accelerated, such acceleration is not annulled, within a period of thirty (30) days after there shall have been given, by registered or certified mail, to the Company by the Trustee or to the Company and the Trustee by the Holders of at least $1,000,000 in aggregate principal amount of the Outstanding Securities a written notice specifying such default and requiring the Company to cause such indebtedness to be discharged or such acceleration to be rescinded or annulled and stating that such notice is a “Notice of Default” hereunder;

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(g) the entry by a court having jurisdiction in the premises of (1) a decree or order for relief in respect of the Company or any Significant Subsidiary in an involuntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or (2) a decree or order adjudging the Company or any Significant Subsidiary a bankrupt or insolvent, or approving as properly filed a petition seeking reorganization, arrangement, adjustment or composition of or in respect of the Company or any Significant Subsidiary under any applicable federal or state law, or appointing a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or any Significant Subsidiary or of any substantial part of its property, or ordering the winding up or liquidation of its affairs, and the continuance of any such decree or order for relief or any such other decree or order unstayed and in effect for a period of sixty (60) consecutive days; or

(h) the commencement by the Company or any Significant Subsidiary of a voluntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or of any other case or proceeding to be adjudicated a bankrupt or insolvent, or the consent by it to the entry of a decree or order for relief in respect of the Company or any Significant Subsidiary in an involuntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or to the commencement of any bankruptcy or insolvency case or proceeding against it, or the filing by it of a petition or answer or consent seeking reorganization or similar relief under any applicable federal or state law, or the consent by it to the filing of such petition or to the appointment of or taking possession by a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or any Significant Subsidiary or of any substantial part of its property, or the making by it of an assignment for the benefit of creditors, or the admission by it in writing of its inability to pay its debts generally as they become due, or the taking of corporate action by the Company or any Significant Subsidiary in furtherance of any such action.

SECTION 4.2 Acceleration of Maturity; Rescission and Annulment .

If an Event of Default (other than an Event of Default specified in Section 4.1(g) or 4.1(h) with respect to the Company) occurs and is continuing, then in every such case the Trustee or each Holder of not less than $1,000,000 in aggregate principal amount of the Outstanding Securities may declare the principal of all the Securities to be due and payable immediately, by a notice in writing to the Company (and to the Trustee if given by the Holders), and upon any such declaration, such principal and all accrued and unpaid interest thereon shall become immediately due and payable. If an Event of Default specified in Section 4.1(g) or 4.1(h) with respect to the Company occurs, the principal of, and accrued and unpaid interest on, all the Securities shall ipso facto become immediately due and payable without any declaration or other Act of the Holder or any act on the part of the Trustee.

If an Event of Default occurs, the outstanding Securities shall bear interest from the date of the event that creates the Event of Default until such Event of Default is cured at the rate of eighteen percent (18%) per annum, regardless of when or whether the Holders deliver a Notice of Default or any Holder or the Trustee declares the outstanding principal balance due and payable as provided in this Section 4.2 .

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At any time after such declaration of acceleration has been made and before a judgment or decree for payment of the money due has been obtained by the Trustee as hereinafter in this Article IV provided, the Holders of a majority in principal amount of the Outstanding Securities, by written notice to the Company and the Trustee, may rescind and annul such declaration of acceleration and its consequences if:

(a) the Company has paid or deposited with the Trustee a sum sufficient to pay:

(1) all overdue interest, if any, on all Securities;

(2) the principal of and premium, if any, on any Securities that have become due otherwise than by such declaration of acceleration and any interest thereon at the rate borne by the Securities;

(3) to the extent permitted by applicable law, interest upon overdue interest at the