ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

Exhibit 99.9a

EXECUTION COPY


ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

THIS ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT (this
"Assignment"), dated as of September 1, 2006, is entered into among Morgan
Stanley Capital I Inc., a Delaware corporation (the "Depositor"), Morgan
Stanley Mortgage Capital Inc. ("MSMCI"), PHH Mortgage Corporation (formerly
known as Cendant Mortgage Corporation) as a seller ("PHH" and, in such
capacity, a "Seller") and servicer (in such capacity, the "Servicer"),
Bishop's Gate Residential Mortgage Trust ("Bishop's Gate" and a "Seller" and,
together with PHH, the "Sellers") and acknowledged by LaSalle Bank National
Association, as trustee (the "Trustee") of Morgan Stanley Mortgage Loan Trust
2006-12XS (the "Trust"), and Wells Fargo Bank, National Association, as master
servicer (or any successor servicer, the "Master Servicer").

RECITALS

WHEREAS MSMCI, the Sellers and the Servicer have entered into a certain
Third Amended and Restated Mortgage Loan Flow Purchase, Sale & Servicing
Agreement, dated as of January 1, 2006 (as amended or modified to the date
hereof, the "Agreement"), pursuant to which MSMCI has acquired certain
Mortgage Loans pursuant to the terms of the Agreement and the Servicer has
agreed to service such Mortgage Loans;

WHEREAS the Depositor has agreed, on the terms and conditions contained
herein, to purchase from MSMCI certain of the Mortgage Loans (the "Specified
Mortgage Loans") which are subject to the provisions of the Agreement and are
listed on the mortgage loan schedule attached as Exhibit I hereto (the
"Specified Mortgage Loan Schedule"); and

WHEREAS the Trustee, on behalf of the Trust, has agreed, on the terms
and conditions contained herein, to purchase from the Depositor the Specified
Mortgage Loans;

NOW, THEREFORE, in consideration of the mutual promises contained herein
and other good and valuable consideration (the receipt and sufficiency of
which are hereby acknowledged), the parties agree as follows:

1. Assignment and Assumption
-------------------------

(a) On and of the date hereof, MSMCI hereby sells, assigns and transfers
to the Depositor all of its right, title and interest in the Specified
Mortgage Loans and all rights and obligations related thereto as provided
under the Agreement to the extent relating to the Specified Mortgage Loans,
the Depositor hereby accepts such assignment from MSMCI (the "First Assignment
and Assumption"), and the Sellers hereby acknowledge the First Assignment and
Assumption.

MSMCI specifically reserves and does not assign to the Depositor
hereunder any and all right, title and interest in, to and under and all
obligations of MSMCI with respect to any Mortgage Loans subject to the
Agreement which are not the Specified Mortgage Loans.

(b) On and of the date hereof, immediately after giving effect to the
First Assignment and Assumption, the Depositor hereby sells, assigns and
transfers to the Trustee, on behalf of the Trust, all of its right, title and
interest in the Specified Mortgage Loans and all rights and obligations
related thereto as provided under the Agreement to the extent relating to the
Specified Mortgage Loans, and the Trustee, on

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behalf of the Trust, hereby accepts such assignment from the Depositor (the
"Second Assignment and Assumption"), and the Sellers hereby acknowledge the
Second Assignment and Assumption.

(c) On and as of the date hereof, MSMCI represents and warrants to the
Depositor and the Trustee that MSMCI has not taken any action that would serve
to impair or encumber the respective ownership interests of the Depositor and
the Trustee in the Specified Mortgage Loans since the date of MSMCI's
acquisition of the Specified Mortgage Loans.

2. Recognition of Trustee
----------------------

(a) From and after the date hereof, both MSMCI and the Sellers shall
note the transfer of the Specified Mortgage Loans to the Trustee, in their
respective books and records and shall recognize the Trustee, on behalf of the
Trust, as of the date hereof, as the owner of the Specified Mortgage Loans,
and Servicer shall service the Specified Mortgage Loans for the benefit of the
Trust pursuant to the Agreement, the terms of which are incorporated herein by
reference. It is the intention of the Sellers, the Servicer, the Depositor,
the Trustee and MSMCI that this Assignment shall be binding upon and inure to
the benefit of the Depositor, the Trustee and MSMCI and their respective
successors and assigns.

(b) Without in any way limiting the foregoing, the parties confirm that
this Assignment includes the rights relating to amendments or waivers under
the Agreement. Accordingly, the right of MSMCI to consent to any amendment of
the Agreement and its rights concerning waivers as set forth in Section 12.07
of the Agreement shall be exercisable, to the extent any such amendment or
waiver affects the Specified Mortgage Loans or any of the rights under the
Agreement with respect thereto (other than the servicing of the Specified
Mortgage Loans, which shall be enforced by the Master Servicer) by the Trustee
as assignee of MSMCI.

(c) It is expressly understood and agreed by the parties hereto that (i)
this Assignment is executed and delivered by LaSalle Bank National
Association, not individually or personally but solely on behalf of the Trust,
as the assignee, in the exercise of the powers and authority conferred and
vested in it, as Trustee, pursuant to the pooling and servicing agreement
dated as of the date hereof among the Depositor, the Master Servicer, Wells
Fargo Bank, National Association, as securities administrator, and the Trustee
(the "Pooling and Servicing Agreement") for the Morgan Stanley Mortgage Loan
Trust 2006-12XS, Mortgage Pass-Through Certificates, Series 2006-12XS, (ii)
each of the representations, undertakings and agreements herein made on the
part of assignee is made and intended not as personal representations,
undertakings and agreements by LaSalle Bank National Association but is made
and intended for the purpose of binding only the Trust, (iii) nothing herein
contained shall be construed as creating any liability for LaSalle Bank
National Association, individually or personally, to perform any covenant
(either express or implied) contained herein, (iv) under no circumstances
shall LaSalle Bank National Association be personally liable for the payment
of any indebtedness or expenses of the Trust, or be liable for the breach or
failure of any obligation, representation, warranty or covenant made or
undertaken by the Trust under this Assignment and (v) all recourse for any
payment liability or other obligation of the assignee shall be had solely to
the assets of the Trust.

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3. Representations and Warranties
------------------------------

(a) The Depositor represents and warrants that it is a sophisticated
investor able to evaluate the risks and merits of the transactions
contemplated hereby, and that it has not relied in connection therewith upon
any statements or representations of the Sellers or MSMCI other than those
contained in the Agreement or this Assignment.

(b) Each of the parties hereto represents and warrants that it is duly
and legally authorized to enter into this Assignment.

(c) Each of the Depositor, MSMCI, Servicer and the Sellers represents
and warrants that this Assignment has been duly authorized, executed and
delivered by it and (assuming due authorization, execution and delivery
thereof by each of the other parties hereto) constitutes its legal, valid and
binding obligation, enforceable against it in accordance with its terms,
except as such enforcement may be limited by bankruptcy, insolvency,
reorganization or other similar laws affecting the enforcement of creditors'
rights generally and by general equitable principles (regardless of whether
such enforcement is considered in a proceeding in equity or at law).

(d) Each Seller hereby restates, as of the Closing Date (as defined in
the Pooling and Servicing Agreement referred to below), the representations
and warranties set forth in the Agreement, other than the representations and
warranties contained in Sections 3.03(4), (20), (21), (25), (31) or (58) of
the Agreement, with respect to each of the Specified Mortgage Loans that were
sold by it under the Agreement, to and for the benefit of the Depositor, the
Trustee and the Trust, and by this reference incorporates such representations
and warranties herein, as of such Closing Date.

(e) The Servicer hereby represents and warrants to the Assignee that, to
the extent the Mortgage Loans will be part of a REMIC, the Servicer shall
service the Mortgage Loans and any real property acquired upon default thereof
(including, without limitation, making or permitting any modification, waiver
or amendment of any term of any Mortgage Loan) in accordance with the
Servicing Agreement, but in no event in a manner that would (a) cause the
REMIC to fail or qualify as a REMIC or (b) result in the imposition of a tax
upon the REMIC (including, but not limited to, the tax on prohibited
transactions as defined in Section 860F(a)(2) of the Code, the tax on
contributions to a REMIC set forth in Section 860G(d) of the Code and the tax
on "net income from foreclosure property" as set forth in Section 860G(c) of
the Code).

4. The Servicer hereby acknowledges that Wells Fargo Bank, National
Association has been appointed as the Master Servicer of the Specified
Mortgage Loans pursuant to the Pooling and Servicing Agreement and, therefore,
has the right to enforce all obligations of the Servicer under the Agreement.
Such rights will include, without limitation, the right to terminate the
Servicer under the Agreement upon the occurrence of an event of default
thereunder, the right to receive all remittances required to be made by the
Servicer under the Agreement, the right to receive all monthly reports and
other data required to be delivered by the Servicer under the Agreement, the
right to examine the books and records of the Servicer, indemnification rights
and the right to exercise certain rights of consent and approval relating to
actions taken by MSMCI. The Servicer shall make all distributions under the
Agreement to the Master Servicer by wire transfer of immediately available
funds to:

Wells Fargo Bank, National Association
ABA Number: 121-000-248
Account Name: Corporate Trust Clearing
Account number: 3970771416

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For further credit to: 50949200, MSM 2006-12XS

The Servicer shall deliver all reports required to be delivered under
the Agreement to the Master Servicer at the following address:

Wells Fargo Bank, National Association
9062 Old Annapolis Road
Columbia, Maryland 21045
Attention: Client Manager, MSM 2006-12XS
Office Number: (410) 884-2000
Telecopier: (410) 715-2380

For the avoidance of doubt, the parties to this Assignment hereby
acknowledge that the Master Servicer shall have no obligation for enforcing or
overseeing the Servicer's activities pursuant to Sections 5.18(c) and (d) of
the Agreement.

5. Amendments to the Agreement
---------------------------

The parties to this Assignment hereby agree to amend the Agreement,
solely with respect to the Specified Mortgage Loans, as follows:

(a) The term "Indemnified Party" is added as a new defined term in
Section 1.01 and shall have the following meaning:

"Indemnified Party: each Party (other than each Seller and the
Servicer) described in the first sentence of Section 13.07(a)
hereof."

(b) The definition of "Permitted Investments" in Section 1.01 shall have
the meaning of such term as defined in the Pooling and Servicing
Agreement.

(c) The definition of "Remittance Date" in Section 1.01 is hereby
amended and restated in its entirety as follows:

"Remittance Date: No later than 2:00 p.m. New York time on the
18th day of each month (or, if such 18th day is not a Business
Day, the following Business Day)."

(d) The definition of "Servicing Criteria" in Section 1.01 is hereby
amended and restated in its entirety as follows:

"Servicing Criteria: The "servicing criteria" set forth in Item
1122(d) of Regulation AB for which the Servicer is responsible as
identified on Exhibit 14 attached hereto."

(e) The penultimate paragraph of Section 3.05 of the Agreement is hereby
amended and restated as follows:

"With respect to any Mortgage Loans sold in a Securitization
Transaction where the Servicer remains as the servicer, the
Servicer agrees that on or before March 1st each year following
the year such Securitization Transaction occurs, the Servicer
shall deliver, and shall cause each subservicert to deliver, to
the depositor and the trustee, a certification in the form
attached as Exhibit 11 hereto, executed by a senior officer of the
Servicer in charge of servicing for use in connection with any
Form 10-K to be filed with the Securities and Exchange Commission
with respect to the securitization trust. The

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obligation to provide such certification will terminate to the
extent the related securitization trust's obligation to file
reports under the Exchange Act, terminates."


(f) The second paragraph of Section 5.13 of the Agreement is hereby
amended and restated in its entirety as follows:

"With respect to any REO Property, the Trustee's name shall
be placed on the title to such REO Property solely as the Trustee
hereunder and not in its individual capacity. The Servicer shall
ensure that the title to such REO Property references the
Agreement and the Purchaser's (or its designee's) capacity
thereunder. Pursuant to its efforts to sell such REO Property, the
Servicer shall either itself or through an agent selected by the
Servicer protect and conserve such REO Property in the same manner
and to such extent as is customary in the locality where such REO
Property is located and may, incident to its conservation and
protection of the interests of the Purchaser, or its designee,
rent the same, or any part thereof, as the Servicer deems to be in
the best interest of the Purchaser, or its designee, for the
period prior to the sale of such REO Property. The Servicer shall
prepare for and deliver to the Purchaser, or its designee, a
statement with respect to each REO Property that has been rented
showing the aggregate rental income received and all expenses
incurred in connection with the maintenance of such REO Property
at such times as is necessary to enable the Purchaser, or its
designee, to comply with the reporting requirements of the REMIC
Provisions. The net monthly rental income, if any, from such REO
Property shall be deposited in the Certificate Account no later
than the close of business on each Determination Date. The
Servicer shall perform the tax reporting and withholding required
by Sections 1445 and 6050J of the Code with respect to
foreclosures and abandonments, the tax reporting required by
Section 6050H of the Code with respect to the receipt of mortgage
interest from individuals and any tax reporting required by
Section 6050P of the Code with respect to the cancellation of
indebtedness by certain financial entities, by preparing such tax
and information returns as may be required, in the form required,
and delivering the same to the Purchaser, or its designee, for
filing.

In the event that the Purchaser, or its designee, acquires
any Mortgaged Property as aforesaid or otherwise in connection
with a default or imminent default on a Mortgage Loan, the
Servicer shall dispose of such Mortgaged Property as soon as
practicable in a manner that maximizes the Liquidation Proceeds
thereof, but in no event later than three years after its
acquisition by the Purchaser, or its designee. In that event, the
Purchaser, or its designee, shall have been supplied with an
Opinion of Counsel to the effect that the holding by the
Purchaser, or its designee, of such Mortgaged Property subsequent
to a three-year period, if applicable, will not result in the
imposition of taxes on "prohibited transactions" of any REMIC as
defined in section 860F of the Code or cause any REMIC to fail to
qualify as a REMIC at any time, the Purchaser, or its designee,
may continue to hold such Mortgaged Property (subject to any
conditions contained in such Opinion of Counsel) after the
expiration of such three-year period. Notwithstanding any other
provision of this Agreement, no Mortgaged Property acquired by the
Purchaser, or its designee, shall be rented (or allowed to
continue to be rented) or otherwise used for the production of
income by or on behalf of the Purchaser, or its designee, in such
a manner or pursuant to any terms that would (i) cause such
Mortgaged Property to fail to qualify as "foreclosure property"
within the meaning of section 860G(a)(8) of the Code or (ii)
subject any REMIC to the imposition of any federal, state or local
income taxes on the income earned from such Mortgaged Property
under Section 860G(c) of the Code or

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otherwise, unless the Servicer has agreed to indemnify and hold
harmless the Purchaser, or its designee, with respect to the
imposition of any such taxes."

(g) The third paragraph of Section 5.13 of the Agreement is hereby
deleted in its entirety.

(h) The first paragraph of Section 6.02 of the Agreement is hereby
amended and restated in its entirety as follows:

"Reporting. Not later than the 5th Business Day of each month, the
Servicer shall forward to the Master Servicer in hard copy and
electronic format a statement in the form of Exhbit 6.02(a) and
Exhibit 6.02(b), certified by a Servicing Officer, setting forth
(a) the amount of the distribution made on such Remittance Date
which is allocable to principal and allocable to interest; (b) the
amount of servicing compensation received by the Servicer during
the prior calendar month; (c) the aggregate Stated Principal
Balance and the aggregate unpaid principal balance of the Mortgage
Loans as of the last day of the preceding month; and (d) the paid
through date for each Mortgage Loan. Such statement shall also
include information regarding delinquencies on Mortgage Loans,
indicating the number and aggregate principal amount of Mortgage
Loans which are either one (1), two (2) or three (3) or more
months delinquent and the book value of any REO Property, or such
other mortgage loan level data as agreed upon by the Servicer and
the Master Servicer, and the monthly reports substantially in the
form of Exhibit 15 attached hereto (or in such other formats
mutually agreed upon between the Servicer and the Master
Servicer). Such monthly reports shall be available by the Servicer
for the Purchaser on Servicer's secured web site. The Servicer
shall provide training, secured access and password(s) to the
Purchaser on the operation of the website."

(i) Section 7.04 of the Agreement is hereby amended and restated in its
entirety as follows:

"Annual Statement as to Compliance. The Servicer shall deliver to
the Purchaser and the Master Servicer, on or before March 1st each
year beginning March 1, 2006, an Officer's Certificate stating
that (a) a review of the activities of the Servicer during the
preceding calendar year and of its performance under this
Agreement has been made under such officer's supervision, and (b)
to the best of such officer's knowledge, based on such review, the
Servicer has fulfilled all its obligations under this Agreement
throughout such year, or, if there has been a default in the
fulfillment of any such obligation, specifying each such default
known to such officer and the nature and status thereof and the
action being taken by the Servicer to cure such default."

(j) Section 7.05 of the Agreement is hereby amended and restated in its
entirety as follows:

"Annual Independent Public Accountants' Servicing Report. On or
before March 1st of each year beginning March 1, 2006, the
Servicer at its expense shall cause a firm of independent public
accountants which is a member of the American Institute of
Certified Public Accountants to furnish a statement to the
Purchaser and the Master Servicer to the effect that such firm
has, with respect to the Servicer's overall servicing operations,
examined such operations in accordance with the requirements of
the Uniform Single Attestation Program for Mortgage Bankers,
stating such firm's conclusions relating thereto."

(k) Section 9.01 of the Agreement is hereby amended to insert the
following as the penultimate paragraph of such Section:

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"In addition, the Servicer shall indemnify and hold harmless
the Master Servicer and each of its directors, officers,
employees, agents, and affiliates from and against any and all
claims, losses, damages, penalties, fines, forfeitures, reasonable
legal fees and related costs, judgments and other costs and
expenses arising out of or based upon (a) any breach by the
Servicer of any if its obligations under hereunder, including
particularly its obligations to provide any Assessment of
Compliance, Attestation Report, Compliance Statement or any
information, data or materials provided by the Servicer hereunder,
or (c) the negligence, bad faith or willful misconduct of the
Servicer in connection with its performance hereunder. If the
indemnification provided for herein is unavailable or insufficient
to hold harmless the Master Servicer, then the Servicer as a
result of any claims, losses, damages or liabilities incurred by
the Master Servicer in such proportion as is appropriate to
reflect the relative fault of the Master Servicer on the one hand
and the Servicer on the other."

(l) The word "or" is deleted from the end of Section 10.01(8), the word
"or" is added at the end of Section 10.01(9) and the following paragraph
is hereby incorporated into the Agreement as new Section 10.01(10):

"(f) failure by the Servicer to duly perform, within the required
time period, its obligations under Sections 7.04 or 7.05 which
failure continues unremedied for a period of fifteen (15) days
after the date on which written notice of such failure, requiring
the same to be remedied, shall have been given to the Servicer by
any party to this Agreement or by any master servicer responsible
for master servicing the Mortgage Loans pursuant to a
securitization of such Mortgage Loans;"

(m) The following paragraph is hereby incorporated into the Agreement as
new Section 12.14:

"Third Party Beneficiary. For purposes of this Agreement,
including but not limited to Section 7.05, any Master Servicer
shall be considered a third party beneficiary to this Agreement
entitled to all the rights and benefits accruing to any Master
Servicer herein as if it were a direct party to this Agreement."

(n) Section 13.03(d) of the Agreement is hereby amended and restated in
its entirety as follows:

"(d) For the purpose of satisfying the reporting obligation under
the Exchange Act with respect to any class of asset-backed
securities, each Seller and the Servicer shall (or shall cause
each Subservicer and Third-Party Originator to) (i) provide prompt
notice to the Purchaser, any Master Servicer and any Depositor in
writing of (A) any material litigation or governmental proceedings
involving the Company, any Subservicer or any Third-Party
Originator, (B) any affiliations or relationships that develop
following the closing date of a Securitization Transaction between
the Company, any Subservicer or any Third-Party Originator and any
of the parties specified in clause (D) of paragraph (a) of this
Section (and any other parties identified in writing by the
requesting party) with respect to such Securitization Transaction,
(C) any Event of Default under the terms of this Agreement or any
Reconstitution Agreement, (D) any merger, consolidation or sale of
substantially all of the assets of the Company, and (E) the
Company's entry into an agreement with a Subservicer to perform or
assist in the performance of any of the Company's obligations
under this Agreement or any Reconstitution Agreement and (ii)
provide to the Purchaser and any Depositor a description of such
proceedings, affiliations or relationships."

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(o) Section 13.03(f) of the Agreement is hereby amended and restated in
its entirety as follows:

"(f) In addition to such information as the Company, as servicer,
is obligated to provide pursuant to other provisions of this
Agreement, not later than ten days prior to the deadline for the
filing of any distribution report on Form 10-D in respect of any
Securitization Transaction that includes any of the Mortgage Loans
serviced by the Company or any Subservicer, the Company or such
Subservicer, as applicable, shall, to the extent the Company or
such Subservicer has knowledge, provide to the party responsible
for filing such report (including, if applicable, the Master
Servicer) notice of the occurrence of any of the following events
along with all information, data, and materials related thereto as
may be required to be included in the related distribution report
on Form 10-D (as specified in the provisions of Regulation AB
referenced below):

(i) any material modifications, extensions or waivers
of pool asset terms, fees, penalties or payments during the
distribution period or that have cumulatively become
material over time (Item 1121(a)(11) of Regulation AB);

(ii) material breaches of pool asset representations
or warranties or transaction covenants (Item 1121(a)(12) of
Regulation AB); and

(iii) information regarding new asset-backed
securities issuances backed by the same pool assets, any
pool asset changes (such as, additions, substitutions or
repurchases), and any material changes in origination,
underwriting or other criteria for acquisition or selection
of pool assets (Item 1121(a)(14) of Regulation AB).

(g) The Company shall provide to the Purchaser, any Master
Servicer and any Depositor, evidence of the authorization of the
person signing any certification or statement, copies or other
evidence of Fidelity Bond Insurance and Errors and Omission
Insurance policy, financial information and reports, and such
other information related to the Company or any Subservicer or the
Company or such Subservicer's performance hereunder."

(p) Section 13.05(1)(a)(iv) of the Agreement is hereby amended and
restated in its entirety as follows:

"(iv) deliver, and cause each subservicer and subcontractor
described in clause (iii) above to deliver, to the Purchaser, any
Depositor and any other Person that will be responsible for
signing the certification (a "Sarbanes Certification") required by
Rules 13a-14(d) and 15d-14(d) under the Exchange Act (pursuant to
Section 302 of the Sarbanes-Oxley Act of 2002) on behalf of an
asset-backed issuer with respect to a Securitization Transaction a
certification, signed by an appropriate officer of the Servicer,
in the form attached hereto as Exhibit 11."

(q) Section 13.06(a) of the Agreement is hereby amended to revise the
number of calendar days in the first sentence of such Section from
"fifteen (15)" to "thirty (30)."

(r) Section 13.06(a) of the Agreement is hereby amended to add Sections
13.03(f) and 13.03(g) as provisions that the Subservicers must comply
with to same extent as if such Subservicer were the Servicer.

(s) The last sentence of the last paragraph of Section 13.06 of the
Agreement is amended to require the Servicer to cause any Subservicer or
Subcontractor to provide any assessment of

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compliance and attestation but also any other certifications required to
delivered under this Section 13.06.

(t) Section 13.07(a)(ii) of the Agreement is hereby amended and restated
in its entirety as follows:

"(ii) any breach by the Seller or Servicer under, or any failure
by any Seller, the Servicer, any Subservicer, any Subcontractor or
any Third-Party Originator to deliver any information, report,
certification, accountants' letter or other material when and as
required, under this Article XIII, including any failure by the
Servicer to identify pursuant to Section 13.06(b) any
Subcontractor "participating in the servicing function" within the
meaning of Item 1122 of Regulation AB;"

(u) The word "or" is struck at the end of Section 13.07(a)(ii) of the
Agreement and the following is inserted to Section 13.07(a) of the
Agreement:

"(iv) negligence, bad faith or willful misconduct of the Servicer
in connection with its performance under this Article XIII.

If the indemnification provided for herein is unavailable or
insufficient to hold harmless an Indemnified Party, then the
Servicer agrees that it shall contribute to the amount paid or
payable by such Indemnified Party as a result of any claims,
losses, damages or liabilities incurred by such Indemnified Party
in such proportion as is appropriate to reflect the relative fault
of such Indemnified Party on the one hand and the Servicer on the
other.

This indemnification shall survive the termination of this
Agreement or the termination of any party to this Agreement."

(v) The following parenthetical is inserted directly before the proviso
in the last sentence of the first paragraph of Section 13.07(b)(i) of
the Agreement:

"(and if the Servicer is servicing any of the Mortgage Loans in a
Securitization Transaction, appoint a successor servicer
reasonably acceptable to the Master Servicer for such
Securitization Transaction)"

(w) Exhibits 6.02(a) and 6.02(b) of the Agreement are hereby deleted and
replaced with Exhibit II to this Assignment.

(x) Exhibit 11 to the Agreement is hereby deleted and replaced with
Exhibit A-1 to this Assignment.

(y) Exhibit 14 to the Agreement is hereby deleted and replaced with
Exhibit B-1 to this Assignment.

(z) Written notice provided in compliance with Sections 13.03(d), (e) or
(f) of the Agreement shall be substantially in the form of Exhibit C-1
to this Assignment.

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6. Continuing Effect
-----------------

Except as contemplated hereby, the Agreement shall remain in full force
and effect in accordance with its terms.

7. Governing Law
-------------

This Assignment and the rights and obligations hereunder shall be
governed by and construed in accordance with the internal laws of the State of
New York.

8. Notices
-------

Any notices or other communications permitted or required under the
Agreement to be made to the Depositor, MSMCI, the Master Servicer, the
Sellers, the Servicer and the Trustee shall be made in accordance with the
terms of the Agreement and shall be sent to the Depositor and Trustee as
follows:

In the case of MSMCI:

Morgan Stanley Mortgage Capital Inc.
1221 Avenue of the Americas
New York, New York 10020
Attention: Morgan Stanley Mortgage Loan Trust 2006-12XS

With a copy to:

Morgan Stanley & Co. Incorporated
1585 Broadway
New York, New York 10036
Attention: General Counsel's Office

In the case of the Depositor:

Morgan Stanley Capital I Inc.
1585 Broadway
New York, New York 10036
Attention: Morgan Stanley Mortgage Loan Trust 2006-12XS

In the case of the Trustee:

LaSalle Bank National Association
135 South LaSalle Street, Suite 1511
Chicago, Illinios 60603
Attention: Global Securities and Trust Services MSM 2006-12XS

In the case of PHH and the Servicer:

PHH Mortgage Corporation
3000 Leadenhall Road
Mt. Laurel, NJ 08054
Attention: Vice President of Servicing

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In the case of Bishop's Gate:

Bishop's Gate Residential Mortgage Trust
c/o PHH Mortgage Corporation
3000 Leadenhall Road
Mt. Laurel, NJ 08054 Attention: Vice President of Servicing

or to such other address as may hereafter be furnished by the Depositor and
the Trustee to the parties in accordance with the provisions of the Agreement.

9. Ratification
------------

Except as modified and expressly amended by this Assignment, the
Agreement is in all respects ratified and confirmed, and all terms, provisions
and conditions thereof shall be and remain in full force and effect.

10. Counterparts
------------

This Assignment may be executed in counterparts, each of which when so
executed shall be deemed to be an original and all of which when taken
together shall constitute one and the same instrument.

11. Definitions
-----------

Any capitalized term used but not defined in this Assignment has the
same meaning as in the Agreement.

[SIGNATURE PAGE FOLLOWS]


11
<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this Assignment the
day and year first above written.

MORGAN STANLEY MORTGAGE CAPITAL INC.


By: /s/ Valerie Kay
-------------------------------
Name: Valerie Kay
Title: Vice President


MORGAN STANLEY CAPITAL I INC.


By: /s/ Valerie Kay
-------------------------------
Name: Valerie Kay
Title: Vice President


PHH MORTGAGE CORPORATION


By: /s/ Chrissy Judge
-------------------------------
Name: Chrissy Judge
Title: Assistant Vice President


BISHOP'S GATE RESIDENTIAL MORTGAGE
TRUST

By: PHH Mortgage Corporation, as
Administrator


By: /s/ Chrissy Judge
-------------------------------
Name: Chrissy Judge
Title: Assistant Vice President


<PAGE>


Acknowledged and Agreed:
WELLS FARGO BANK, NATIONAL
ASSOCIATION, as Master Servicer


By: /s/ Patricia Russo
-----------------------------------
Name: Patricia Russo
Title: Vice President

LASALLE BANK, NATIONAL
ASSOCIATION, as Trustee of Morgan Stanley
Mortgage Loan Trust 2006-12XS


By: /s/ Rita Lopez
-----------------------------------
Name: Rita Lopez
Title: Vice President

<PAGE>


EXHIBIT I

Mortgage Loan Schedule

[see Schedule A to Pooling and Servicing Agreement]


I-1
<PAGE>


Exhibit IIA: Standard File Layout - Delinquency Reporting
<TABLE>
<CAPTION>

----------------------------------------------------------------------------------------------------
Column/Header Name Description Decimal Format
Comment
----------------------------------------------------------------------------------------------------
<S> <C> <C> <C>
SERVICER_LOAN_NBR A unique number assigned to a loan by the
Servicer. This may be different than the
LOAN_NBR
----------------------------------------------------------------------------------------------------
LOAN_NBR A unique identifier assigned to each loan
by the originator.
----------------------------------------------------------------------------------------------------
CLIENT_NBR Servicer Client Number
----------------------------------------------------------------------------------------------------
SERV_INVESTOR_NBR Contains a unique number as assigned by an
external servicer to identify a group of
loans in their system.
----------------------------------------------------------------------------------------------------
BORROWER_FIRST_NAME First Name of the Borrower.
----------------------------------------------------------------------------------------------------
BORROWER_LAST_NAME Last name of the borrower.
----------------------------------------------------------------------------------------------------
PROP_ADDRESS Street Name and Number of Property
----------------------------------------------------------------------------------------------------
PROP_STATE The state where the property located.
----------------------------------------------------------------------------------------------------
PROP_ZIP Zip code where the property is located.
----------------------------------------------------------------------------------------------------
BORR_NEXT_PAY_DUE_DATE The date that the borrower's next payment MM/DD/YYYY
is due to the servicer at the
end of processing cycle, as reported by
Servicer.
----------------------------------------------------------------------------------------------------
LOAN_TYPE Loan Type (i.e. FHA, VA, Conv)
----------------------------------------------------------------------------------------------------
BANKRUPTCY_FILED_DATE The date a particular bankruptcy claim MM/DD/YYYY
was filed.
----------------------------------------------------------------------------------------------------
BANKRUPTCY_CHAPTER_CODE The chapter under which the bankruptcy
was filed.
----------------------------------------------------------------------------------------------------
BANKRUPTCY_CASE_NBR The case number assigned by the court to
the bankruptcy filing.
----------------------------------------------------------------------------------------------------
POST_PETITION_DUE_DATE The payment due date once the bankruptcy MM/DD/YYYY
has been approved by the courts
-------------------------------------------------------------------------------------------------