INDENTURE OF LEASE

Exhibit 10.1

100 HAYDEN AVENUE

LEXINGTON, MASSACHUSETTS

Lease Dated May 22, 2008

THIS INSTRUMENT IS AN INDENTURE OF LEASE in which the Landlord and the Tenant are the parties hereinafter named, and which relates to space in a certain building (the “Building”) known as, and with an address at, 100 Hayden Avenue, Lexington, Massachusetts.

The parties to this Indenture of Lease hereby agree with each other as follows:

ARTICLE I

Reference Data

1.1            Subjects Referred To

Each reference in this Lease to any of the following subjects shall be construed to incorporate the data stated for that subject in this Article:

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1.2            Exhibits

1.3            Table of Articles and Sections

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ARTICLE II

The Buildings, Premises, Term and Rent

2.1            The Premises

Landlord hereby demises and leases to Tenant, and Tenant hereby hires and accepts from Landlord, Tenant’s Space in the Building excluding the roof (but subject to Tenant’s

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rights under Section 8.27 hereof), and if Tenant’s Space is less than the entire Building excluding exterior faces of exterior walls, the common stairways and stairwells, elevators and elevator wells, fan rooms, electric and telephone closets, janitor closets, and pipes, ducts, conduits, wires and appurtenant fixtures serving exclusively or in common other parts of the Building and if Tenant’s Space includes less than the entire rentable area of any floor, excluding the common corridors, elevator lobbies and toilets located on such floor.

Tenant’s Space with such exclusions is hereinafter referred to as the “Premises.” The term “Building” means the Building identified on the first page, and which is the subject of this Lease and being one of the two (2) Buildings erected on the Site by the Landlord; the term “Site” means all, and also any part of the Land described in Exhibit A, plus any additions or reductions thereto resulting from the change of any abutting street line and all parking areas and structures. The term “Property” means the two (2) Buildings and the Site.

2.2            Rights to Use Common Facilities

Subject to Landlord’s right to change or alter any of the following in Landlord’s discretion as herein provided, Tenant shall have, as appurtenant to the Premises, the non- exclusive right to use in common with others, subject to reasonable rules of general applicability to tenants of the Complex from time to time made by Landlord of which Tenant is given notice common walkways and driveways necessary for access to the Building.

2.2.1         Tenant’s Parking

In addition, Tenant shall have the exclusive right, as appurtenant to the Premises, to use, without additional charge, the portion of the parking area shown on the Parking Plan as “100 Hayden Parking Area”.  The Number of Parking Spaces (referred to in Section 1.1) for the parking of employee automobiles and other passenger vehicles (and the occasional parking of delivery vans) not longer than thirty (30) feet and no more than two such delivery vans at any one time, provided, however, that Tenant shall be responsible for moving such delivery vans in order for Landlord to perform snow plowing and parking lot maintenance; and provided further that Landlord shall not be obligated to furnish stalls or spaces in any parking area specifically designated for Tenant’s use. In the event that the Rentable Floor Area of the Premises decreases at any time during the Lease Term, the Number of Parking Spaces provided to Tenant hereunder shall be reduced proportionately.  In no event shall Tenant have any right to use parking spaces in the portion of the parking area shown on the Parking Plan as “92 Hayden Parking Area”.  Tenant covenants and agrees that it and all persons claiming by, through and under it, shall at all times abide by all reasonable rules and regulations promulgated by Landlord by notice to Tenant with respect to the use of the parking areas on the Site.  The parking privileges granted herein are non-transferable

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except to a permitted assignee or subtenant as provided in Section 5.6 through Section 5.6.5.  Further, Landlord assumes no responsibility whatsoever for loss or damage due to fire, theft or otherwise to any automobile(s) parked on the Site or to any personal property therein, however caused, and Tenant covenants and agrees, upon request from Landlord from time to time, to notify its officers, employees, agents and invitees of such limitation of liability. Tenant acknowledges and agrees that a license only is hereby granted, and no bailment is intended or shall be created.

2.3            Landlord’s Reservations

In the event that Tenant’s Space is less than the entire Building, Landlord reserves the right from time to time, without unreasonable interference with Tenant’s use: (a) to install, use, maintain, repair, replace and relocate for service to the Premises and other parts of the Building, or either, pipes, ducts, conduits, wires and appurtenant fixtures, wherever located in the Premises or Building, and (b) to alter or relocate any other common facility, provided that substitutions are substantially equivalent or better. Installations, replacements and relocations referred to in clause (a) above shall be located so far as practicable in the central core area of the Building, above ceiling surfaces, below floor surfaces or within perimeter walls of the Premises.  Any non-emergency work performed pursuant to this Section 2.3 shall be performed at such times and in such a manner so as to minimize interference with Tenant’s operations in the Premises.  Any non-emergency work shall be performed only after reasonable advance notice to Tenant.

2.4            Habendum

Tenant shall have and hold the Premises for a period commencing on the date of this Lease (the “Commencement Date”), and continuing for the Term unless sooner terminated as provided in Article VI or Article VII or unless extended as provided in Section 8.20.

2.5            Fixed Rent Payments

Tenant agrees to pay to Landlord, or as directed by Landlord, at Landlord’s Original Address specified in Section 1.1 hereof, or at such other place as Landlord shall from time to time designate by notice, (1) on the Rent Commencement Date (defined in Section 1.1 hereof) and thereafter monthly, in advance, on the first day of each and every calendar month during the Original Term, a sum equal to one twelfth (1/12 ^th ) of the Annual Fixed Rent (sometimes hereinafter referred to as “fixed rent”) and (2) on the first day of each and every calendar month during each extension option period (if exercised), a sum equal to (a) one twelfth (1/12 ^th ) of the annual fixed rent as determined in Section 8.20 for the applicable extension option period. Until notice of some other designation is given, fixed rent and all other charges for which provision is herein made shall be paid by remittance to or for the order of Boston Properties Limited Partnership either (i) by mail to P.O. Box 3557, Boston, Massachusetts 02241-3557, (ii) by wire transfer to Bank of

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America in Dallas, Texas, Bank Routing Number 0260-0959-3 or (iii) by ACH transfer to Bank of America in Dallas, Texas, Bank Routing Number 111 000 012, and in the case of (ii) or (iii) referencing Account Number 3756454460, Account Name of Boston Properties, LP, Tenant’s name and the Property address. All remittances received by Boston Properties Limited Partnership, as Agents as aforesaid, or by any subsequently designated recipient, shall be treated as payment to Landlord.

Annual Fixed Rent for any partial month shall be paid by Tenant to Landlord at such rate on a pro rata basis, and, if the Rent Commencement Date is a day other than the first day of a calendar month, the first payment of Annual Fixed Rent which Tenant shall make to Landlord shall be a payment equal to a proportionate part of such monthly Annual Fixed Rent for the partial month from the Rent Commencement Date to the first day of the succeeding calendar month.

Additional Rent payable by Tenant on a monthly basis, as hereinafter provided, likewise shall be prorated, and the first payment on account thereof shall be determined in similar fashion but shall commence on the Commencement Date; and other provisions of this Lease calling for monthly payments shall be read as incorporating this undertaking by Tenant.

Notwithstanding that the payment of Annual Fixed Rent payable by Tenant to Landlord shall not commence until the Rent Commencement Date, Tenant shall be subject to, and shall comply with, all other provisions of this Lease as and at the times provided in this Lease.

The Annual Fixed Rent and all other charges for which provision is herein made shall be paid by Tenant to Landlord, without offset, deduction or abatement except as otherwise specifically set forth in this Lease.

Notwithstanding anything contained herein or in Section 1.1 to the contrary, it is understood and agreed that in the event that this Lease is terminated by reason an Event of Default during the first thirty (30) months of the Term, Annual Fixed Rent for the period commencing on the Commencement Date and ending on the last day of the free rent period shall immediately become due and payable in the amount of $766,624.83. Tenant shall within ten (10) days after demand therefor pay Landlord any amounts necessary so that the total Annual Fixed Rent for such period shall equal $766,624.83 as aforesaid (taking into account any amounts previously paid by Tenant as Annual Fixed Rent during such period).

2.6            Operating Expenses

“Landlord’s Operating Expenses” means reasonable, out of pocket the cost of operation of the Building and the Site which shall exclude costs of special services rendered to tenants (including Tenant) for which a separate charge is made, but shall include, without limitation, the following: premiums for insurance carried with respect to the Building and

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the Site (including, without limitation, liability insurance, insurance against loss in case of fire or casualty and insurance of monthly installments of fixed rent and any Additional Rent which may be due under this Lease and other leases of space in the Building for not more than 12 months in the case of both fixed rent and Additional Rent and if there be any first mortgage of the Property, including such insurance as may be required by the holder of such first mortgage); compensation and all fringe benefits, worker’s compensation insurance premiums and payroll taxes paid to, for or with respect to all persons engaged in the managing, operating, maintaining or cleaning of the Building or Site, water, sewer, electric, gas, oil and telephone charges including utilities charges for parking lot lighting (excluding utility charges separately chargeable to tenants for additional or special services); cost of building and cleaning supplies and equipment; cost of maintenance, cleaning and repairs (other than repairs not properly chargeable against income or reimbursed from contractors under guarantees); cost of snow removal and care of landscaping; payments under service contracts with independent contractors; management fees at reasonable rates consistent with the type of occupancy and the service rendered; costs of maintaining a regional property management office in connection with the operation, management and maintenance of the Building (sometimes called the “Regional Property Management Charge”); and all other reasonable and necessary expenses paid in connection with the operation, cleaning and maintenance of the Building and the Site and properly chargeable against income, provided, however, there shall be included (a) depreciation for capital expenditures made by Landlord during the Lease Term, but only to the extent the same are incurred either (i) to reduce Landlord’s Operating Expenses if Landlord shall have reasonably determined that the annual reduction in Landlord’s Operating Expenses shall exceed depreciation therefor or (ii) to comply with applicable laws, rules, regulations, requirements, statutes, ordinances, by-laws and court decisions of all public authorities which are now or hereafter in force (the capital expenditures described in subsections (i) and (ii) being hereinafter referred to as “Permitted Capital Expenditures”); plus (b) in the case of both (i) and (ii) an interest factor, reasonably determined by Landlord, as being the interest rate then charged for long term mortgages by institutional lenders on like properties within the locality in which the Building is located; depreciation in the case of both (i) and (ii) shall be determined by dividing the original cost of such capital expenditure by the number of years of useful life of the capital item acquired and the useful life shall be reasonably determined by Landlord in accordance with generally accepted accounting principles and practices in effect at the time of acquisition of the capital item.

Notwithstanding the foregoing provisions, the following shall be excluded from Landlord’s Operating Expenses:

(1)            Leasing fees or commissions, advertising and promotional expenses, legal fees, the cost of tenant improvements, build out allowances, moving expenses, and other concessions and expenses incurred in connection with leasing spacing in the Building;

(2)            Interest on indebtedness, debt amortization, ground rent, and refinancing costs for

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any mortgage or ground lease of the Building, the Complex, or any portion of either of them;

(3)            If the Building shall become a multi-tenant building (i.e., the Building is occupied by two (2) or more tenants, each under a direct lease with Landlord), costs incurred in performing work or furnishing services for any tenant (including Tenant), to the extent that such work or services is in excess of any work or service Landlord is obligated to provide Tenant under this Lease without additional charge.  However, as between Landlord and Tenant, the provisions of Section 4.1.2 shall apply in the case of additional services requested by Tenant to be performed by Landlord;

(4)            The cost of any item or service to the extent to which Landlord is reimbursed or compensated by insurance, any tenant, or any third party;

(5)            The cost of repairs or replacements incurred by reason of fire or other casualty or condemnation other than costs not in excess of the deductible on any insurance maintained by Landlord which provides a recovery for such repair or replacement, which deductible shall be as reasonably determined by Landlord;

(6)            Any advertising, promotional or marketing expenses for the Building;

(7)            With the exception of the management fee described in the first paragraph of this Section 2.6 and an allocable portion of the property management office costs and expenses of Landlord or Boston Properties, the cost of any service or materials provided by any party related to Landlord, to the extent such costs exceed the reasonable cost for such service or materials absent such relationship in buildings similar to the Buildings in the vicinity of the Buildings (if, in any calendar year, the percentage of revenues used to calculate the management fee shall be greater than the percentage used to calculate the management fee included in Base Operating Expenses, then Base Operating Expenses shall be adjusted and shall be in effect from the year in which the management fee percentage is increased and shall be the management fee that would have been payable, and calculated on the rental income, for calendar year 2009 as if such higher percentage were then in effect.);

(8)            Penalties and interest for late payment of any obligations of Landlord, including, without limitation, taxes, insurance, equipment leases and other past due amounts, provided that Tenant pays Operating Costs and real estate taxes timely as and when due;

(9)            Salaries or other compensation paid to employees above the grade of Regional Property Manager except that if any such employee performs a service which would have been performed by an outside consultant, the compensation paid to such employee for performing such service shall be included in Operating

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Expenses for the Building to the extent only that the cost of such service does not exceed the costs of such service had such service been performed by an outside consultant.  Further, if and to the extent an employee performs services at the Building and other properties, such employee’s labor costs shall be reasonably allocated and only the portion reasonably allocable to the Building shall be included in Landlord’s Operating Expenses (Nothing contained herein shall affect Landlord’s right to collect the management fee specifically provided for above.);

(10)          Cost of purchasing or installing sculpture, paintings or other objects of art;

(11)          Cost of repairs, replacements, alterations or improvements necessary to make the Building comply with applicable law in effect as of the date of this Lease;

(12)          Legal fees or other expenses incurred in connection with negotiating and enforcing leases with tenants in the Complex;

(13)          Depreciation, except that “Permitted Capital Expenditures” (as hereinbefore defined) and interest and amortization thereon, which shall include payments for rented equipment to the extent that such rented equipment would, if purchased, constitute a Permitted Capital Expenditure or would be used in performing the work which constitutes a Permitted Capital Expenditure , shall be included in Operating Expenses;

(14)          All costs and expenses of any special events (e.g. receptions, concerts); provided, however, that Tenant shall pay the entire costs and expenses of any special events run by Tenant;

(15)          All legal, architectural, engineering, accounting and other professional fees; provided, however, that, subject to the provisions of item 1 above, legal, architectural, engineering, accounting and other professional fees and costs incurred in connection with the management, operation, maintenance, repair and replacement of the Complex shall be included in Operating Expenses;

(16)          All costs and expenses attributable to any hazardous wastes, substances, or materials existing as of the date of this Lease (but not any which subsequently arise, other than by reason of the acts or omissions of Landlord, its agents, contractors, or employees) and/or any testing, investigation, reporting, management, maintenance, remediation, or removal thereof; provided, however, Tenant shall be solely responsible for all such costs and expenses for all hazardous wastes, substances and materials resulting from, or caused by Tenant or its contractors, subcontractors, agents, employees or invitees and the cost of testing, investigation, reporting, management, maintenance, remediation and removal thereof. However, there shall be included in Operating Expenses the cost of Landlord’s routine annual or other periodic hazardous material or similar inspection of the buildings, the cost of which incurred during the Base Year shall also be included in Base Operating Expenses (and Landlord agrees that Base

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Operating Expenses shall include an amount equal to the cost of such annual inspection, whether or not an annual inspection is actually performed during calendar year 2009);

(17)          All charitable or political contributions;

(18)          Reserves, provided, however, amounts actually expended in maintaining, repairing and operating the Property shall be included in Operating Expenses;

(19)          Costs incurred with respect to the Additional Building or any other building that may from time to time exist on the Site (a “Future Building”); provided, however, that any costs relating to the common areas of the Site) shall be reasonably allocated among the Building, the Additional Building and any Future Building;

(20)          All costs and expenses arising out of (i) any violation of law or legal requirement by Landlord, (ii) any violation or breach of any lease of space in the Building, or (iii) any other breach of contract by Landlord;

(21)          All general corporate overhead of Landlord or any its agents or affiliates; and

(22)          Any management fee other than the management fee and the Regional Property Management Charge set forth in the first paragraph of this Section 2.6; provided, however, that if Tenant requests Landlord or its managing agent to perform work for Tenant beyond that which is covered by this Section 2.6, the same shall be done on a work order basis for which Landlord shall have the right to charge Tenant for Landlord’s performing same.

In addition to the foregoing, if in any calendar year after 2009 Landlord shall provide a service that was not provided in 2009, then Base Operating Expenses shall be adjusted to include the reasonable estimate of the cost of providing such services in calendar year 2009. Further, if in any calendar year after 2009, Landlord with Tenant’s consent shall cease to provide a service that was provided in 2009, then Base Operating Expenses shall be adjusted to exclude the cost of providing such services in calendar year 2009.

“Operating Expenses Allocable to the Premises” shall mean (a) the same proportion of Landlord’s Operating Expenses for and pertaining to the Building as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Building plus (b) the same proportion of Landlord’s Operating Expenses for and pertaining to the Site as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Buildings.

“Base Operating Expenses” is hereinbefore defined in Section 1.1.  Base Operating Expenses shall not include (i) market wide cost increases due to extraordinary circumstances, including but not limited to Force Majeure (as defined in Section 6.1), conservation surcharges, boycotts, strikes, embargoes or shortages (“Temporary Cost

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Increase”); provided, however, that if any item(s) of Temporary Cost Increases shall continue uninterrupted beyond calendar year 2009, then the amount of such Temporary Cost Increase excluded from Base Operating Expenses with respect to such item(s) shall also be excluded from Landlord’s Operating Expenses for and with respect to any such calendar year during which such Temporary Cost Increase continues and (ii) the cost of any Permitted Capital Expenditures; provided, however, that any Permitted Capital Expenditures excluded from Base Operating Expenses shall not be included in Landlord’s Operating Expenses in any subsequent year.

“Base Operating Expenses Allocable to the Premises” means (i) the same proportion of Base Operating Expenses for and pertaining to the Building as the Rentable Floor Area of Tenant’s Space bears to 100% of the Rentable Floor Area of the Building plus (ii) the same proportion of Base Operating Expenses for and pertaining to the Site as the Rentable Floor Area of Tenant’s Space bears to 100% of the Rentable Floor Area of the Buildings.

If with respect to any calendar year falling within the Term, or fraction of a calendar year falling within the Term at the beginning or end thereof, the Operating Expenses Allocable to the Premises for a full calendar year exceed Base Operating Expenses Allocable to the Premises, or for any such fraction of a calendar year exceed the corresponding fraction of Base Operating Expenses Allocable to the Premises then, Tenant shall pay to Landlord, as Additional Rent, the amount of such excess. Such payments shall be made at the times and in the manner hereinafter provided in this Section 2.6 (the Base Operating Expenses Allocable to the Premises do not include the tenant electricity to be paid by Tenant at the time of payment of Annual Fixed Rent, separate provision being made in Section 2.8 of this Lease for Tenant’s electricity costs for the Premises).

Not later than one hundred and twenty (120) days after the end of the first calendar year or fraction thereof ending December 31 and of each succeeding calendar year during the Term or fraction thereof at the end of the Term, Landlord shall render Tenant a statement in reasonable detail and according to usual accounting practices certified by a representative of Landlord, showing for the preceding calendar year or fraction thereof, as the case may be, Landlord’s Operating Expenses and Operating Expenses Allocable to the Premises (the “Annual Statement”). The Annual Statement shall also show for the preceding year or fraction thereof as the case may be the amounts of operating expenses already paid by Tenant as Additional Rent, and the amount of operating expenses remaining due from, or overpaid by, Tenant for the year or other period covered by such statement. Within thirty (30) days after the date of delivery of such statement, Tenant shall pay to Landlord the balance of the amounts, if any, required to be paid pursuant to the above provisions of this Section 2.6 with respect to the preceding year or fraction thereof, or Landlord shall credit any amounts due from it to Tenant pursuant to the above provisions of this Section 2.6 against (i) monthly installments of fixed rent next thereafter coming due or (ii) any sums then due from Tenant to Landlord under this Lease (or refund such portion of the overpayment as aforesaid if the Term has ended, net of any sums then due from Tenant to Landlord).

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In addition, Tenant shall make payments monthly on account of Tenant’s share of increases in Landlord’s Operating Expenses anticipated for the then current year at the time and in the fashion herein provided for the payment of fixed rent. The amount to be paid to Landlord shall be an amount reasonably estimated annually by Landlord to be sufficient to cover, in the aggregate, a sum equal to Tenant’s share of such increases in operating expenses for each calendar year during the Term.

Notwithstanding the foregoing, in determining the amount of Landlord’s Operating Expenses for any calendar year or portion thereof falling within the Lease Term, if less than ninety-five percent (95%) of the Total Rentable Floor Area of the Building shall have been occupied by tenants at any time during the period in question, then those components of Landlord’s Operating Expenses that vary based on occupancy for such period shall be adjusted to equal the amount such components of Landlord’s Operating Expenses would have been for such period had occupancy been ninety-five percent (95%) throughout such period.

Subject to the provisions of this paragraph and provided that no Event of Default then exists, Tenant shall have the right, at Tenant’s cost and expense, to examine all documentation and calculations prepared in the determination of Operating Expenses Allocable to the Premises:

(1)               Such documentation and calculation shall be made available to Tenant at the office (located in the Eastern continental United States) where Landlord keeps such records, during normal business hours within thirty (30) days after Landlord receives a written request from Tenant to make such examination.

(2)               Tenant shall have the right to make such examination no more than once in respect of any period in which Landlord has given Tenant a statement of the actual amount of Landlord’s Operating Expenses.

(3)               Any request for examination in respect of any Operating Year may be made no more than one hundred eighty (180) days after Landlord delivers the Annual Statement with respect to such period and such examination shall be completed within ninety (90) days after it is commenced, time being of the essence in respect of both periods.

(4)               Such examination may be made only by (i) an independent certified public accounting firm, or (ii) a qualified real estate professional or firm approved by Landlord, which approval shall not be unreasonably withheld. Without limiting Landlord’s approval rights, Landlord may withhold its approval of any examiner of Tenant who is being paid by Tenant on a contingent fee basis.

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(5)               As a condition to performing any such examination, Tenant and its examiners shall be required to execute and deliver to Landlord a commercially reasonable agreement pursuant to which Tenant and its examiners agree to keep confidential any information which either of them discovers about Landlord or the Building in connection with such examination, subject only to those exceptions customarily found in such agreements. Without limiting the foregoing, such examiners shall be required to agree that they will not represent any other tenant in the Building or in the other buildings on the Site.

2.7            Real Estate Taxes

If with respect to any full Tax Year or fraction of a Tax Year falling within the Term, Landlord’s Tax Expenses Allocable to the Premises as hereinafter defined for a full Tax Year exceed Base Taxes Allocable to the Premises, or for any such fraction of a Tax Year exceed the corresponding fraction of Base Taxes Allocable to the Premises then, on or before the thirtieth (30 ^th ) day following receipt by Tenant of the certified statement referred to below in this Section 2.7, then Tenant shall pay to Landlord, as Additional Rent, the amount of such excess. Not later than ninety (90) days after Landlord’s Tax Expenses Allocable to the Premises are determined for the first such Tax Year or fraction thereof and for each succeeding Tax Year or fraction thereof during the Term, Landlord shall render Tenant a statement in reasonable detail certified by a representative of Landlord showing for the preceding year or fraction thereof, as the case may be, real estate taxes on the Building and the Site and abatements and refunds of any taxes and assessments. Expenditures for legal fees and for other expenses incurred in seeking the tax refund or abatement may be charged against the tax refund or abatement before the adjustments are made for the Tax Year. Said statement to be rendered to Tenant shall also show for the preceding Tax Year or fraction thereof as the case may be the amounts of real estate taxes already paid by Tenant as Additional Rent, and the amount of real estate taxes remaining due from, or overpaid by, Tenant for the year or other period covered by the statement. Within thirty (30) days after the date of delivery of the foregoing statement, Tenant shall pay to Landlord the balance of the amounts, if any, required to be paid pursuant to the above provisions of this Section 2.7 with respect to the preceding Tax Year or fraction thereof, or Landlord shall credit any amounts due from it to Tenant pursuant to the provisions of this Section 2.7 against (i) monthly installments of fixed rent next thereafter coming due or (ii) any sums then due from Tenant to Landlord under this Lease (or refund such portion of the over-payment as aforesaid if the Term has ended, net of any sums then due from Tenant to Landlord).

In addition, payments by Tenant on account of increases in real estate taxes anticipated for the then current year shall be made monthly at the time and in the fashion herein provided for the payment of fixed rent. The amount so to be paid to Landlord shall be an amount reasonably estimated by Landlord to be sufficient to provide Landlord, in the aggregate, a sum equal to Tenant’s share of such increases, at least ten (10) days before the day on which such payments by Landlord would become delinquent.

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To the extent that real estate taxes shall be payable to the taxing authority in installments with respect to periods less than a Tax Year, the foregoing statement shall be rendered and payments made on account of such installments.

Terms used herein are defined as follows:

(i)             “Tax Year” means the twelve-month period beginning July 1 each year during the Term or if the appropriate governmental tax fiscal period shall begin on any date other than July 1, such other date.

(ii)            “Landlord’s Tax Expenses Allocable to the Premises” shall mean (a) the same proportion of Landlord’s Tax Expenses for and pertaining to the Building as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Building plus (b) the same proportion of Landlord’s Tax Expenses for and pertaining to the Site as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Buildings.

(iii)           “Landlord’s Tax Expenses” with respect to any Tax Year means the aggregate real estate taxes on the Building and Site with respect to that Tax Year, reduced by any abatement receipts with respect to that Tax Year.

(iv)           “Base Taxes” is hereinbefore defined in Section 1.1.

(v)            “Base Taxes Allocable to the Premises” means (i) the same proportion of Base Taxes for and pertaining to the Building as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Building, plus (ii) the same proportion of Base Taxes for and pertaining to the Site as the Rentable Floor Area of Tenant’s Space bears to 100% of the Total Rentable Floor Area of the Buildings.

(vi)           “Real estate taxes” means all taxes and special assessments of every kind and nature and user fees and other like fees assessed by any governmental authority on the Building or Site which the Landlord shall become obligated to pay because of or in connection with the ownership, leasing and operation of the Site, the Building and the Property and reasonable expenses of and fees for any formal or informal proceedings for negotiation or abatement of taxes (collectively, “Abatement Expenses”), which Abatement Expenses shall be excluded from Base Taxes.  The amount of special taxes or special assessments to be included shall be limited to the amount of the installment (plus any interest, other than penalty interest, payable thereon) of such special tax or special assessment required to be paid during the year in respect of which such taxes are being

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determined, calculated as if Landlord had elected to pay such special taxes or assessments over the longest period allowed by law (whether or not Landlord actually so elects). There shall be excluded from such taxes all income, estate, succession, inheritance, franchise and transfer taxes, and, provided that Tenant has timely paid all amounts due from Tenant under this Section 2.7, any fees, penalties, or interest payable on account of the late payment of any real estate taxes.  If at any time during the Term the present system of ad valorem taxation of real property shall be changed so that in lieu of the whole or any part of the ad valorem tax on real property there shall be assessed on Landlord a capital levy or other tax on the gross rents received with respect to the Site or Building or Property, or a federal, state, county, municipal, or other local income, franchise, excise or similar tax, assessment, levy or charge distinct from any now in effect in the jurisdiction in which the Property is located) measured by or based, in whole or in part, upon any such gross rents, then any and all of such taxes, assessments, levies or charges, to the extent so measured or based, shall be deemed to be included within the term “real estate taxes” but only to the extent that the same would be payable if the Site and Buildings were the only property of Landlord.

(vii)          If during the Lease Term the Tax Year is changed by applicable law to less than a full 12-month period, the Base Taxes and Base Taxes Allocable to the Premises shall each be proportionately reduced.

(viii)         If Landlord shall receive any refund of any real estate taxes of which Tenant has paid a portion pursuant to this Section 2.7, then, out of any balance remaining after deducting Landlord’s reasonable expenses incurred in obtaining such refund, Landlord shall pay or credit to Tenant its proportionate share of said balance, prorated as set forth above, but in no event more than the amount paid by the Tenant with respect to the fiscal year in question.

Tenant shall not have the right to seek an abatement of real estate taxes, but provided Tenant has not assigned this Lease nor sublet more than one (1) full floor in the Building, and there shall not be existing an Event of Default, Tenant shall have the right to request that Landlord seek and abatement of real estate taxes at Tenant’s sole cost and expense. Landlord agrees to act reasonably with respect to any such request including meeting with Tenant.

2.8                                  Tenant Electricity

Commencing on the Commencement Date and continuing throughout the Term (as it may be extended), Tenant covenants and agrees to pay directly to the appropriate utility company providing electricity to the Site, as Additional Rent, all electricity charges for

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lights, power and heating, ventilating and air conditioning consumed at the Premises and for other purposes within the Building (“Tenant Electricity”) and all electricity for exterior lighting of the Building (and not the exterior of the Additional Building) (“Exterior Electricity”).  There are presently two (2) electric meters, one of which reads only the electricity to power heating, ventilating and air-conditioning to the Premises and the other of which reads both the Exterior Electricity and the Tenant Electricity, and no other electric usage, and Tenant shall be responsible for the full payment of all electrical charges associated with both meters.

Tenant covenants and agrees to take all steps required by the appropriate utility company to provide for the direct billing to Tenant of the Tenant Electricity and the Exterior Electricity including, without limitation, making application(s) to such utility company in connection therewith and making any deposits (including, but not limited to, such letters of credit) as such utility company shall require.  Tenant covenants and agrees to pay, before delinquency, all electricity charges and rates for and relating to the Tenant Electricity and the Exterior Electricity and from time to time if requested by Landlord to provide Landlord with evidence of payment to, and good standing with, such utility company as Landlord may reasonably require but not more frequently than twice in any calendar year unless an Event of Default (hereinafter defined) exists in which case there shall be no limitation on the frequency of such request.

ARTICLE III

Condition of Premises; Alterations

3.1                                  Tenant covenants and agrees that Tenant is leasing the Premises in their as-is condition on the Commencement Date and that, except as expressly provided in the following sentence, Landlord has no obligation to perform or make any additions, alterations, improvements, demolition or other work to the Premises, the Building or the Site.  Notwithstanding the foregoing, Landlord agrees that, as of the Commencement Date, the utility and building service systems and equipment serving the Premises shall be in good operating order and condition; provided, however, that the items listed on Exhibit E hereto shall be delivered in their “as is” condition.  Further, Tenant acknowledges and agrees that the Commencement Date is a fixed date (being the date of the Lease) and that the Rent Commencement Date also is a fixed date (being February 1, 2009) notwithstanding that Tenant plans to perform improvement and other work in and to the Premises and irrespective of when Tenant begins such work and how long Tenant takes to complete such work. In addition, neither the Commencement Date nor the Rent Commencement Date shall be extended for any reason whatsoever including, without limitation, the time it takes for certificates of occupancy to be issued by the Town of Lexington for Tenant’s improvement work in and to the Premises, Tenant hereby acknowledging and agreeing that Tenant is solely responsible for obtaining all such certificates of occupancy.  Landlord agrees to cooperate in good faith with Tenant, at no out of pocket expense to Landlord, in Tenant’s efforts to obtain such certificates of

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occupancy.

3.2                                  (A)      Tenant, at its sole cost and expense, shall perform all work necessary to prepare the Premises for Tenant’s occupancy in accordance with plans and specifications prepared by Baker Design Group, or another  architect licensed by the Commonwealth of Massachusetts and approved by Landlord, which approval shall not be unreasonably withheld, delayed, or conditioned, such plans and specifications to be subject to the reasonable approval of the Landlord as set forth below. Tenant hereby acknowledges that the lobby in the Building, including its floor, walls, ceiling, doors and equipment (collectively, the “Lobby”), are new and that in no event shall Tenant make any changes, renovations, alterations or substitutions to or in the Lobby. Further, during the performance of any demolition or improvement work in the Building, Tenant shall take all steps reasonably required by Landlord to protect the Lobby from damage and shall obtain Landlord’s approval which approval shall not be unreasonably withheld, delayed, or conditioned for the methods of such protection prior to Tenant performing (or allowing any contractors to perform) any work in the Premises.

Tenant shall submit to Landlord a detailed floor plan layout together with working drawings (the “Tenant’s Submission”) for work to be performed by Tenant to prepare the Premises for Tenant’s occupancy (“Tenant’s Work”). Such floor plan layout and working drawings (the “Plans”) shall contain at least the information required by, and shall conform to the requirements of, Exhibit B. Tenant’s submission shall include at least two (2) full sized sets and two (2) half size sets of Tenant’s proposed layout and working drawings. Landlord’s approval of the Plans shall not be unreasonably withheld or delayed; however, Landlord’s determination of matters relating to aesthetic issues relating to alterations or changes which are visible outside the Premises shall be in Landlord’s sole discretion. Landlord shall have seven (7) business days from Tenant’s submission made in accordance with the requirements hereof to respond to Tenant’s request for approval thereof.  If Tenant’s submission does not comply with requirements hereof, Landlord shall notify Tenant of same within two (2) business days after Tenant makes any such defective submission, which notice shall specify the respects in which such submission is defective.  Any disapproval of any Plans shall set forth in reasonable detail the grounds for such disapproval along with Landlord’s suggested corrective measures.   If Landlord disapproves of any Plans, then Tenant shall promptly have the Plans revised by its architect to incorporate all objections and conditions presented by Landlord and shall resubmit such plans to Landlord no later than seven (7) days after Landlord has submitted to Tenant its objections and conditions.  Landlord shall have five (5) calendar days from Tenant’s resubmission to respond to Tenant’s request for approval thereof. Such process shall be followed until the Plans shall have been approved by the Landlord without objection or condition.  If Landlord fails to respond in writing to Tenant within in the applicable period specified above (i.e., seven (7) business days after Tenant’s initial submission and five (5) calendar days after any resubmission), then the submitted plans shall be deemed approved for all purposes of this Article III.

If in connection with the review of Tenant’s Plans by the Town of Lexington Building

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Commissioner at the time of Tenant’s submission of an application for a building permit for Tenant’s Work, it is determined by said Building Commissioner that the existing lobby/atrium and /or the existing means of egress of the Building does not comply with applicable Legal Requirements and that modification thereto is required, Landlord, at its sole cost and expense, shall perform modification work to the lobby/atrium and/or means of egress which will bring such areas into compliance with the applicable Legal Requirements and will otherwise be done aesthetically in a manner as determined by Landlord.  If any such modification work shall be required, the same shall be performed by Landlord’s contractors concurrently with Tenant’s performance of Tenant’s Work.

Notwithstanding the foregoing, Tenant shall be solely responsible for compliance of Tenant’s Plans with applicable Legal Requirements, and in the event that (a) any Tenant’s Work performed in or adjacent to the existing lobby/atrium area as shown on Exhibit D makes necessary the performance of any other work in such lobby/atrium or the other existing means of egress from the Building in order for such lobby/atrium or the other means of egress to comply with applicable Legal Requirements, or (b) any of Tenant’s Work in the Building is for uses other than general office purposes (and accessory cafeteria and other customary uses accessory to general office uses) and results in the existing lobby/atrium area or the other existing means of egress from the Building not complying with applicable Legal Requirements, then Tenant, at its sole cost and expense, shall be obligated to perform the work necessary to provide compliance with applicable Legal Requirements (including the applicable Massachusetts Building Code).

(B)      Once the Plans have been approved by Landlord, Tenant, at its sole cost and expense, shall promptly, and with all due diligence, perform Tenant’s Work as set forth on the Plans, and, in connection therewith, the Tenant shall obtain all necessary governmental permits and approvals for Tenant’s Work.  Landlord shall cooperate with Tenant, at no out of pocket expense to Landlord and with no liability to Landlord, in Tenant’s efforts to obtain such permits and approvals.   All of Tenant’s Work shall be performed strictly in accordance with the Plans and in accordance with applicable Legal Requirements (as defined in Section 3.4 hereof) and Insurance Requirements (as defined in Section 5.14 hereof). Tenant shall have Tenant’s Work performed by a general contractor first approved by Landlord,  which approval shall not be unreasonably withheld, delayed, or conditioned, which contractor shall provide to Landlord such insurance as the Landlord may reasonably require. Landlord has provided to Tenant rules and regulations relative to the performance of Tenant’s Work and any other work which the Tenant may perform under this Lease and Tenant shall abide by all such reasonable rules and regulations and shall cause all of its contractors to so abide.  Notwithstanding anything set forth in said rules and regulations, not later than twenty one (21) days after the date of this Lease, Tenant shall pay to Landlord a one time access fee of $2,500.00 in lieu of any and all other fees for accessing the Building during the performance of Tenant’s Work.  It shall be Tenant’s obligation to obtain a certificate or certificates of occupancy or other like governmental approval for the use and occupancy of the Premises to the extent required by law, and Tenant shall not occupy the Premises for the conduct of business until and unless it has obtained such approval and has submitted to Landlord a

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copy of the same. However, the Commencement Date and the Rent Commencement Date shall be the fixed dates as set forth in Section 3.1 hereof. Tenant shall also prepare and submit to Landlord promptly after Tenant’s Work is substantially complete a set of as-built plans in both print and electronic forms showing the work performed by Tenant to the Premises including, without limitation, any wiring or cabling installed by Tenant or Tenant’s contractor for Tenant’s computer, telephone and other communication systems.

3.3                                  Special Allowance .

Landlord shall provide to Tenant a special allowance of $2,236,960.00 (being the product of (i) $40.00 and (ii) the Rentable Floor Area of the Premises (the “Tenant Allowance”). The Tenant Allowance shall be used and applied by Tenant solely on account of the cost of Tenant’s Work and the “Applicable Design Costs” (hereinafter defined).  Provided that Tenant is not in default beyond the expiration of any applicable notice or grace period of its obligations under the Lease at the time that Tenant requests any requisition on account of Tenant’s Allowance, Landlord shall pay to Tenant a portion of the cost of the work shown on each requisition (as hereinafter defined) submitted by Tenant to Landlord within thirty (30) days of submission thereof by Tenant to Landlord, such portion calculated as follows:  If there shall be such a default, Landlord shall not be obligated to continue funding the Tenant Allowance until and unless such default is fully cured within the applicable grace period.  If such default is not so cured within the grace period, Landlord shall have no obligation to continue funding.  Each requisition shall set forth the total cost of Tenant’s Work (which term, for the purpose hereof, shall include Approved Design Costs) incurred during the period covered by such requisition. Landlord shall pay for and with respect to each such requisition an amount equal to the product of (i) the cost of Tenant’s Work set forth in such requisition, multiplied by (ii) a fraction, the numerator of which is the total amount of the Tenant Allowance and the denominator of which is the total amount of the cost of Tenant’s Work (excluding, however, the cost of any so-called “demountable wall systems” or other portions, if any, of Tenant’s Work toward which the Tenant Allowance may not be applied).  Notwithstanding the foregoing, (a) in no event shall Landlord be required to pay more than the total amount of Tenant’s Allowance, and (b) the final payment(s) of Tenant’s Allowance shall, if necessary for Tenant to receive the total amount of Tenant’s Allowance that Tenant is otherwise entitled to receive hereunder, be increased to the extent necessary for Tenant to receive such total amount.  For the purposes hereof, a “requisition” shall mean written documentation showing in reasonable detail the costs of the improvements then installed by Tenant in the Premises (i.e., the Tenant’s Work).  Each requisition shall be accompanied by evidence reasonably satisfactory to Landlord that all work covered by previous requisitions has been fully paid by Tenant.  Further, the parties hereby acknowledge that the provisions of the next to last sentence of Section 5.14 of this Lease shall apply to all of Tenant’s Work under this Article III.  At Landlord’s request from time to time, Tenant shall deliver lien waivers from all contractors and subcontractors performing Tenant’s Work.  Landlord shall have the right, upon reasonable advance notice to Tenant, to examine Tenant’s invoices relating to each requisition in order to verify the amount thereof.  Tenant shall submit requisition(s) no more often than monthly. For the purposes hereof, the cost to be so

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reimbursed by Landlord shall consist solely of the cost of leasehold improvements and the Approved Design Costs (hereinafter defined) but not the cost of any of Tenant’s personal property, trade fixtures or trade equipment or any so-called soft costs or other design costs in excess of the Approved Design Costs. The “Approved Design Costs” shall mean the architectural, engineering and space planning fees and charges actually paid by Tenant to third party, unaffiliated architects, engineers and space planners respecting the preparation of Tenant’s Plans but not to exceed the product of (i) $5.00 and (ii) the 55,924 square feet of Rentable Floor Area of the Premises. Notwithstanding the foregoing, Landlord shall be under no obligation to apply any portion of the Tenant Allowance for any purposes other than as provided in this Section 3.4, nor shall Landlord be deemed to have assumed any obligations, in whole or in part, of Tenant to any contractors, subcontractors, suppliers, workers or materialmen. Further, the Tenant Allowance shall only be applied towards the cost of leasehold improvements and the Approved Design Costs but in no event shall Landlord be required to make application of any portion of the Tenant Allowance towards Tenant’s personal property any “demountable wall systems”, if any, trade fixtures or moving expenses or on account of any supervisory fees, overhead, management fees or other payments to Tenant, to any partner or affiliate of Tenant or to any third party excepting “Approved Design Costs” (hereinabove defined) and payments to Tenant’s contractors. In the event that such cost of Tenant’s Work, including the Approved Design Costs, is less than the Tenant Allowance, Tenant shall not be entitled to any payment or credit nor shall there be any application of the same toward Annual Fixed Rent or Additional Rent owed by Tenant under this Lease.

3.4                                  Quality and Performance of Work

All construction work required or permitted by this Lease shall be done in a good and workmanlike manner and in compliance with all applicable laws, ordinances, rules, regulations, statutes, by-laws, court decisions, and orders and requirements of all public authorities (“Legal Requirements”) and all Insurance Requirements. All of Tenant’s work shall be coordinated with any work being performed by or for Landlord and in such manner as to maintain harmonious labor relations. Each party may inspect the work of the other at reasonable times and shall promptly give notice of observed defects. Each party authorizes the other to rely in connection with design and construction upon approval and other actions on the party’s behalf by any Construction Representative of the party named in Section 1.1 or any person hereafter designated in substitution or addition by notice to the party relying. Tenant acknowledges that Tenant is acting for its own benefit and account and that Tenant will not be acting as Landlord’s agent in performing any Tenant Work, accordingly, no contractor, subcontractor or supplier shall have a right to lien Landlord’s interest in the Property in connection with any work.

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ARTICLE IV

Landlord’s Covenants; Interruptions and Delays

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or duty to be performed on Landlord’s part, by reason of any cause reasonably beyond Landlord’s control, including without limitation the causes set forth in Section 3.2 hereof as being reasonably beyond Landlord’s control, Landlord shall not be liable to Tenant therefor, nor, except as expressly otherwise provided in Article VI, shall Tenant be entitled to any abatement or reduction of rent by reason thereof, or right to terminate this Lease, nor shall the same give rise to a claim in Tenant’s favor that such failure constitutes actual or constructive, total or partial, eviction from the Premises.

Landlord reserves the right to stop any service or utility system, when necessary by reason of accident or emergency, or until necessary repairs have been completed; provided, however, that in each instance of stoppage, Landlord shall exercise reasonable diligence to eliminate the cause thereof. Except in case of emergency repairs, Landlord will give Tenant reasonable advance notice of any contemplated stoppage and will use reasonable efforts to avoid unnecessary inconvenience to Tenant by reason thereof.

(B)      Notwithstanding the foregoing, upon the occurrence of any event or circumstance resulting from or caused by (x) any failure of Landlord to provide electrical, heating, ventilating, air conditioning, or all elevator service to the Premises or access to the Premises that prevents Tenant from using the Premises or any portion thereof or (y) any alterations, replacements, or improvements made by Landlord to other tenant premises within the Building (any such event or circumstance described in clauses (x) or (y) above being hereinafter referred to as an “Abatement Event”), Tenant shall give Landlord notice (“Abatement Notice”) of any such Abatement Event and if such Abatement Event continues beyond the Eligibility Period (as hereinafter defined), then the Annual Fixed Rent shall be abated entirely or reduced, as the case may be, after the expiration of the Eligibility Period for such time that Tenant continues both to be so prevented from using, and does not use, the Premises or a portion thereof, in the proportion that the rentable area of the portion of the Premises that Tenant is prevented from using, and does not use, bears to the total Rentable Floor Area of the Premises. The term “Eligibility Period” shall mean (i) in connection with a failure by Landlord to provide required services or access to the Premises due to an event or circumstance within Landlord’s reasonable control or in connection with any alterations, replacements, or improvements made by Landlord to other tenant premises within the Building, a period of five (5) consecutive business days after Landlord’s receipt of any Abatement Notice(s) and (ii) in connection with a failure by Landlord to provide required services or access to the Premises due to an event or circumstance not within Landlord’s reasonable control, a period of  fourteen (14) consecutive business days after Landlord’s receipt of any Abatement Notice(s).

4.3                                  Landlord’s Indemnity

(a)     Indemnity .  Subject to the limitations in Section 8.4 and in Section 5.7.1 and Section 5.8 of this Lease, and to the extent not resulting from any act, omission, fault, negligence or misconduct of Tenant or its contractors, licensees, invitees, agents, servants or employees, Landlord agrees to indemnify and save harmless Tenant from and against any claim by a third party arising from any injury to or death of any person or damage to or

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destruction of the property of any person other than Tenant occurring in the Premises or in the Complex after the date that possession of the Premises is first delivered to Tenant and until the expiration or earlier termination of the Lease Term, to the extent such injury results from the negligence or willful misconduct of Landlord or Landlord’s employees, or from any breach or default by Landlord in the performance or observance of its covenants or obligations under this Lease; provided, however, that in no event shall the aforesaid indemnity render Landlord responsible or liable for any loss or damage to fixtures, personal property or other property of Tenant, and Landlord shall in no event be liable to Tenant for any indirect, consequential or punitive damages.  Tenant shall provide notice of any such third party claim to Landlord as soon as practicable.  The provisions of this Section shall not be applicable to the holder of any mortgage now or hereafter on the Property, the Complex or the Building (whether or not such holder shall be a mortgagee in possession of or shall have exercised any rights under a conditional, collateral or other assignment of leases and/or rents respecting the Property, the Complex or the Building) unless and until such mortgagee shall enter into actual physical possession of the Complex in which case such mortgagee shall be bound under this Section 4.3 for events covered by this Section 4.3 but only first actually occurring from and after the date such mortgagee enters into actual physical possession of the Complex subject to the limitations set forth in Section 8.4, 5.7.1 and 5.8 of this Lease.

(b)   Breach .  In the event that Landlord breaches any of its indemnity obligations hereunder or under any other contractual or common law indemnity: (i) Landlord shall pay to the Tenant Parties all liabilities, loss, cost, or expense (including reasonable attorney’s fees) reasonably incurred by the Tenant Parties as a result of said breach; and (ii) the Tenant Parties may deduct and offset from any amounts due to Landlord under this Lease any amounts owed by Landlord pursuant to this section.

(c)   No limitation .  The indemnification obligations under this Section shall not be limited in any way by any limitation on the amount or type of damages, compensation or benefits payable by or for Landlord under workers’ compensation acts, disability benefit acts, or other employee benefit acts.  Landlord waives any immunity from or limitation on its indemnity or contribution liability to the Tenant Parties based upon such acts.

(d)   Survival .  The terms of this section shall survive any termination or expiration of this Lease.

(e)   Costs .  The foregoing indemnity and hold harmless agreement shall include indemnity for all reasonable costs, expenses and liabilities (including, without limitation, attorneys’ fees and disbursements) incurred by the Tenant Parties in connection with any such claim or any action or proceeding brought thereon, and the defense thereof.  In addition, in the event that any action or proceeding shall be brought against one or more Tenant Parties by reason of any such claim, Landlord, upon request from the Tenant Party, shall resist and defend such action or proceeding on behalf of the Tenant Party by counsel appointed by Landlord’s insurer (if such claim is covered by insurance without

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reservation) or otherwise by counsel reasonably satisfactory to the Tenant Party.  The Tenant Parties shall not be bound by any compromise or settlement of any such claim, action or proceeding without the prior written consent of such Tenant Parties, which consent shall not be unreasonably withheld.  Such consent shall not be required for any compromise or settlement pursuant to which the Tenant Parties are completely released from liability.

(f)  The provisions of this Section 4.3 are subject to the limitations set forth in Section 8.4 hereof.

4.4                                  Landlord’s Insurance

(a)   Required insurance .  Landlord shall maintain insurance against loss or damage with respect to the Building on an “all risk” type insurance form, with customary exceptions, subject to such commercially reasonable deductibles as Landlord may determine, in an amount equal to at least the replacement value of the Building.  Landlord shall also maintain such insurance with respect to any improvements, alterations, and permanent fixtures of Tenant located at the Premises but Landlord shall not be obligated to insure Tenant’s Property or any demountable walls or partitions.  Landlord shall maintain a policy of commercial general liability insurance, on an occurrence basis, issued on a form at least as broad as Insurance Services Office (“ISO”) Commercial General Liability Coverage “occurrence” form CG 00 01 10 01 or another ISO Commercial General Liability “occurrence” form providing equivalent coverage.  Such insurance shall include broad form contractual liability coverage, specifically covering but not limited to the indemnification obligations undertaken by Landlord in this Lease.  The minimum limits of liability of such insurance shall be $5,000,000.00 per occurrence per location.  Landlord shall maintain worker’s compensation insurance or participation in a monopolistic state workers’ compensation fund.  The cost of such insurance shall be treated as a part of Operating Expenses.  Such insurance shall be maintained with an insurance company selected by Landlord.  Payment for losses thereunder shall be made solely to Landlord.  Upon Tenant’s reasonable request from time to time but not more frequently than once each calendar year, Landlord shall provide Tenant with certificates evidencing the insurance coverage required by this Lease.

(b)   Optional insurance .  Landlord may maintain such additional insurance with respect to the Building, the Site and the Complex, including, without limitation, earthquake insurance, terrorism insurance, flood insurance, liability insurance, pollution liability insurance and/or rent insurance, as Landlord may in its reasonable business judgment elect, provided that such additional insurance is customarily carried by the owners of buildings similar to the Buildings in the metropolitan Boston area.  Landlord may also maintain such other insurance as may from time to time be required by any Mortgagee.  The cost of all such additional insurance shall also be part of the Operating Expenses.

(c)   Blanket and self-insurance .  Any or all of Landlord’s insurance may be

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provided by blanket coverage maintained by Landlord or any affiliate of Landlord under its insurance program for its portfolio of properties, or by a commercially reasonable program of self-insurance maintained by Boston Properties Limited Partnership and/or Boston Properties, Inc. (or by any successor landlord) through a captive insurance company authorized and regulated by a state government of one of the United States or by the government of the captive’s domicile, and in such event Operating Expenses shall include the portion of the reasonable cost of blanket insurance that is equitably allocable to the Building.  In addition, with respect to self-insurance:

(i)             the cost of such self insurance included in Operating Expenses shall not exceed the cost that Landlord would have incurred to purchase from an insurance company the insurance coverage provided by such self insurance;

(ii)            the cost to repair any damage covered by such self-insurance shall not be included in Operating Expenses except for an amount equal to a commercially reasonable deductible under a third-party policy; and

(iii)           the provisions of Section 5.8 hereof shall operate to release Tenant from liability for any loss or damage covered by such self-insurance if and to the extent that such self-insurance replaces insurance which Landlord would otherwise have been required to maintain under this Lease but for Landlord’s decision to self-insure such risk.

(d)   No obligation .  Landlord shall not be obligated to insure, and shall not assume any liability of risk of loss for, Tenant’s Property, including any such property of tenant’s subtenants or occupants.  Landlord will also have no obligation to carry insurance against, nor (except as set forth in Section 4.2(B))  be responsible for, any loss suffered by Tenant, subtenants or other occupants due to interruption of Tenant’s or any subtenant’s or occupant’s business.

4.5                                  Hazardous Materials

Landlord represents to Tenant that to the best of Landlord’s actual knowledge as of the Date of this Lease, except as set forth in that certain “Report On Oil And Hazardous Material Site Evaluation Update, 92-100 Hayden Avenue, Lexington, Massachusetts” by Haley & Aldrich, Inc., (File No. 11817-040 dated September, 1996) and that certain “Asbestos Survey Report, 92-100 Hayden Avenue, Lexington, Massachusetts” prepared for Boston Properties, Inc. by Covino Environmental Associates, Inc., dated May 20, 1997 (Covino Project No. 97-00226) (copies of which have been previously provided to Tenant), there are no Hazardous Materials (as that term is defined in Section 5.3 below, which term, for the purposes hereof, shall also include mold) in the Building or on, at, beneath, or migrating from the Site which are required to be investigated, removed, or otherwise abated in accordance with applicable Hazardous Materials Laws.  Subject to the limitations of Section 8.4 hereof, Landlord shall remove or abate as required by

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applicable Hazardous Materials Laws Hazardous Materials on, at, beneath, or migrating from the Site or in the Building, provided that the foregoing removal and/or abatement requirements shall not apply to Hazardous Materials (including mold) which first become present in the Building or on the Site after the Commencement Date (x) because of the use, action or (where action is required hereunder or under Hazardous Materials Laws) inaction of any tenant or occupant in the Site, including Tenant, or any employee, agent or contractor of Tenant or (y) because of any use, alterations or other construction by or for Tenant or any occupant (other than any Landlord Party) of the Building (items (x) and (y) being herein collectively called the “Exclusions”).  Subject to the limitations of Section 8.4 hereof, Landlord agrees to defend, indemnify, and save Tenant harmless from liability, loss and damage to persons or property and from any claims (including, without limitation, bodily injury, property damage, and environmental clean up claims and notices of responsibility), actions, proceedings and expenses in connection therewith resulting from (1) the inaccuracy of Landlord’s representation in the first sentence of this Section 4.5; (2) the presence of Hazardous Materials on, at, beneath, or migrating from the Site or in the Building, except to the extent present as a result of the action of Tenant, or any employee, agent or contractor of Tenant; or (3) the failure of Landlord to fulfill its obligations under the second sentence of this Section 4.5; provided, however, that in no event shall the foregoing indemnity (i) cover or in any way include the Exclusions and (ii) render Landlord liable for any loss or damage to Tenant’s Property and Landlord shall in no event be liable for indirect, consequential or punitive damages.  This indemnity and hold harmless agreement shall survive the expiration or earlier termination of this Lease.

4.6                                  Compliance with Law

To comply with all applicable Legal Requirements now or hereafter in force that impose a duty on Landlord with respect to the common areas of the Complex.

4.7                                  Furniture Removal

Within twenty (20) days following execution of this Lease by both Tenant and Landlord, Landlord shall, at its sole expense, remove all furniture currently located in the Premises other than the fixtures and equipment listed on Exhibit E attached hereto (the “Remaining Equipment”). Tenant shall have the right to use the Remaining Equipment throughout the Term and, at the expiration of the Term, shall return the Remaining Equipment to Landlord in good condition, reasonable wear and tear excepted.

4.8                                  Cafeteria Operations

Reference is made to the fact that there presently exists within the Building a cafeteria area (the “Cafeteria Space”) and cafeteria equipment.  During the term of this Lease, Tenant shall have the right, at its sole cost and expense, to operate a cafeteria in the Cafeteria Space for the conduct of a food service for Tenant’s employees and business invitees but not for the general public provided, however, that Tenant shall first obtain and shall keep in full force and effect such special permits, approvals, licenses and other approvals as shall be required by applicable laws, by-laws, orders, rules and regulations. 

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In connection with the operation of such cafeteria, Tenant may enter into a food service contract with a cafeteria operator or other food service provider.  Landlord shall have no liability under such contract but shall have a right to review and approve such contract. Landlord shall have no responsibility for maintenance, repair or replacement of the cafeteria equipment.

ARTICLE V

Tenant’s Covenants

Tenant covenants and agrees to the following during the Term and such further time as Tenant occupies any part of the Premises:

5.1                                  Payments

To pay when due all fixed rent and Additional Rent and all charges for utility services rendered to the Premises (except as otherwise provided in Exhibit C) and, as further Additional Rent, all charges for additional services rendered pursuant to Section 4.1.2.

5.2                                  Repair and Yield Up

Except as otherwise provided in Article VI and Section 4.1.3 to keep the Premises in good order, repair and condition, and all glass in windows (except glass in exterior walls unless the damage thereto is attributable to Tenant’s negligence or misuse) and doors of the Premises whole and in good condition with glass of the same type and quality as that injured or broken, in each case reasonable wear and tear, damage by fire or other casualty or taking under the power of eminent domain and damage resulting from the negligence of any of the Landlord Parties, their agents, contractors or employees or from the failure of Landlord to perform its obligations under this Lease only excepted, and at the expiration or termination of this Lease peaceably to yield up the Premises including all construction, work, improvements, and all alterations and additions thereto in good order, repair and condition, reasonable wear and tear only excepted, first removing all furniture, fixtures, equipment, goods and effects of Tenant and, to the extent specified by Landlord by notice to Tenant given at least thirty (30) days before such expiration or termination, the wiring for Tenant’s computer, telephone and other communication systems and equipment whether located in the Premises or in any other portion of the Building, including all risers and all alterations and additions made by Tenant (but specifically excluding all cabling and wiring existing in the Premises as of the date of this Lease) and all partitions, and repairing any damage caused by such removal and restoring the Premises and leaving them clean and neat. Tenant shall not permit or commit any waste, and Tenant shall be responsible for the cost of repairs which may be made necessary by reason of damage to common areas in the Building, to the Site or to the other Buildings caused by Tenant, Tenant’s agents, contractors, employees, sublessees, licensees, concessionaires or invitees.

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5.3                                  Use

To use and occupy the Premises for no other purpose other than the Permitted Use, and not to injure or deface the Premises, Building, the Additional Building, the Site or any other part of the Site nor to permit in the Premises or on the Site any auction sale, vending machine (other than those used exclusively by Tenant’s personnel), or inflammable fluids or chemicals (except as set forth in the last grammatical paragraph of this Section 5.3), or nuisance, or the emission from the Premises of any objectionable noise or odor, nor to permit in the Premises anything which would  in any way result in the leakage of fluid or the growth of mold, and not to use or devote the Premises or any part thereof for any purpose other than the Permitted Uses, nor any use thereof which is inconsistent with the maintenance of the Building as an office building of the first class in the quality of its maintenance, use and occupancy, or which is likely to disturb the quiet enjoyment of other occupants of the Building or the Additional Building, contrary to law or ordinance or liable to invalidate or increase the premiums for any insurance on the Building or its contents or liable to render necessary any alteration or addition to the Building. Further, (i) Tenant shall not, nor shall Tenant permit its employees, invitees, agents, independent contractors, contractors, assignees or subtenants to, keep, maintain, store or dispose of (into the sewage or waste disposal system or otherwise) or engage in any activity which might produce or generate asbestos, petroleum (and any breakdown product thereof), lead containing paint, PCBs, and any other substance which is or may hereafter be classified as a hazardous material, waste or substance (collectively “Hazardous Materials”), under federal, state or local laws, rules and regulations, including, without limitation, 42 U.S.C. Section 6901 et seq., 42 U.S.C. Section 9601 et seq., 42 U.S.C. Section 2601 et seq., 49 U.S.C. Section 1802 et seq. and Massachusetts General Laws, Chapter 21E and the rules and regulations promulgated under any of the foregoing, as such laws, rules and regulations may be amended from time to time (collectively “Hazardous Materials Laws”), (ii) Tenant shall promptly after becoming aware of same notify Landlord of any incident in, on or about the Premises, the Building or the Site that would require the filing of a notice under any Hazardous Materials Laws, (iii) Tenant shall comply and shall cause its employees, invitees, agents, independent contractors, contractors, assignees and subtenants to comply with each of the foregoing and (iv) Landlord shall have the right to make such inspections (including testing) as Landlord shall elect from time to time to determine that Tenant is complying with the foregoing.

Notwithstanding the foregoing, Tenant may use normal amounts and types of substances typically used for office uses, provided that Tenant uses such substances in the manner which they are normally used for office uses, and in compliance with all Hazardous Materials Laws and other applicable laws, ordinances, bylaws, rules and regulations, and Tenant obtains and complies with all permits required by Hazardous Materials Laws or any other laws, ordinances, bylaws, rules or regulations prior to the use or presence of any such substances in the Premises.

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5.4                                  Obstructions; Items Visible From Exterior; Rules and Regulations .

Not to obstruct in any manner any portion of the Building not hereby leased or any portion thereof or of the Additional Building or of the Site used by Tenant in common with others; not without prior consent of Landlord to permit the painting or placing of any signs, curtains, blinds, shades, awnings, aerials or flagpoles, or the like, visible from outside the Premises; and to comply with all reasonable Rules and Regulations now or hereafter made by Landlord, of which Tenant has been given notice, for the care and use of the Building and Site and their facilities and approaches; Landlord shall not be liable to Tenant for the failure of other occupants of the Buildings to conform to such Rules and Regulations.

5.5                                  Safety Appliances

To keep the Premises equipped with all safety appliances required by any public authority because of (i) any use made by Tenant other than normal office use, (ii) Tenant’s particular configuration of furniture within the Premises,  (iii) any alterations, additions or improvements made by or on behalf of Tenant in the Premises, or (iv) any subletting of any portion of the Premises, and to procure all licenses and permits so required because of any of the foregoing items described in clauses (i), (ii), (iii), or (iv) above, it being understood that the foregoing provisions shall not be construed to broaden in any way Tenant’s Permitted Use.  Landlord agrees to provide any other safety appliances so required by law (i.e., except to the extent the same are required by reason of clauses (i), (ii), (iii), or (iv) above), the cost of which shall be included in Landlord’s Operating Expenses to the extent provided in Section 2.6 above.

5.6                                  Assignment; Sublease

Except as otherwise expressly provided herein, Tenant covenants and agrees that it shall not assign, mortgage, pledge, hypothecate or otherwise transfer this Lease and/or Tenant’s interest in this Lease or sublet (which term, without limitation, shall include granting of concessions, licenses or the like) the whole or any part of the Premises. Any assignment, mortgage, pledge, hypothecation, transfer or subletting not expressly permitted herein or consented to by Landlord under Sections 5.6.1-5.6.5 shall be void, ab initio; shall be of no force and effect; and shall confer no rights on or in favor of third parties. In addition, Landlord shall be entitled to seek specific performance of or other equitable relief with respect to the provisions hereof.

5.6.1    Notwithstanding the foregoing provisions of Section 5.6 above and the provisions of Sections 5.6.2, 5.6.3, and 5.6.4 below, but subject to the provisions of Section 5.6.5, below Tenant shall have the right without Landlord’s consent to assign this Lease or to sublet the Premises (in whole or in part) (i) to any entity controlling, controlled by, or under common control with Tenant (any such entity referred to in this item (i), a “Tenant Affiliate”), (ii) or to any entity into which Tenant may be converted or with which it may merge, or (iii) to any entity that acquires substantially all of the stock of Tenant or the assets of Tenant, provided that the entity (other than a Tenant Affiliate) to which this

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Lease is so assigned or which so sublets the Premises and/or any guarantor of such entity has a credit worthiness (e.g., assets on a pro forma basis using generally accepted accounting principles consistently applied and using the most recent financial statements) which is the same or better than the Tenant as of the date of this Lease.  For the purposes of the preceding sentence, “control” shall mean ownership, direct or indirect, of the majority of the voting equity interests in any such entity.  Any of the transfers described in this Section 5.6.1 is referred to herein as a “Permitted Transfer”.

5.6.1.1 Notwithstanding the provisions of Section 5.6 above but subject to the provisions of this Section 5.6.1.1 and the provisions of Sections 5.6.3, 5.6.4 and 5.6.5, Tenant may sublease up to and including one (1) specific full floor of the Building (as distinguished from floor area on a number of floors totaling the square footage of any given floor) provided that in each instance Tenant, at its sole cost and expense, shall construct such demising walls and secondary or additional means of ingress and egress as shall be required by applicable Legal Requirements and provided, further, that in each instance Tenant first obtains the express prior written consent of Landlord, which consent shall not be unreasonably withheld, conditioned or delayed.  Landlord shall not be deemed to be unreasonably withholding its consent to such a proposed subleasing if:

(a)                                   the proposed subtenant is (i) a tenant or subtenant in the  Additional Building and Landlord then has available for lease space in the Additional Building  comparable in size to the space proposed to be subleased to such subtenant or (iii) not of a character consistent with the operation of a first class office and development building (by way of example, Landlord shall not be deemed to be unreasonably withholding its consent to a subleasing to any governmental or quasi-governmental agency that regularly deals with the publ