Document:

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                                                                  Exhibit 10.2.2

                      NON-QUALIFIED STOCK OPTION AGREEMENT

                                 METABOLIX, INC.

     AGREEMENT made as of the __ day of _________ 200_, between Metabolix, Inc.
(the "Company"), a Delaware corporation, and _______________ (the
"Participant").

     WHEREAS, the Company desires to grant to the Participant an Option to
purchase shares of its common stock, $.01 par value per share (the "Shares"),
under and for the purposes set forth in the Company's 2005 Stock Plan (the
"Plan");

     WHEREAS, the Company and the Participant understand and agree that any
terms used and not defined herein have the same meanings as in the Plan; and

     WHEREAS, the Company and the Participant each intend that the Option
granted herein shall be a Non-Qualified Option.

     NOW, THEREFORE, in consideration of the mutual covenants hereinafter set
forth and for other good and valuable consideration, the parties hereto agree as
follows:

     1.      GRANT OF OPTION.

     The Company hereby grants to the Participant the right and option to
purchase all or any part of an aggregate of _______________ Shares, on the terms
and conditions and subject to all the limitations set forth herein, under United
States securities and tax laws, and in the Plan, which is incorporated herein by
reference. The Participant acknowledges receipt of a copy of the Plan.

     2.      PURCHASE PRICE.

     The purchase price of the Shares covered by the Option shall be $_____ per
Share, subject to adjustment, as provided in the Plan, in the event of a stock
split, reverse stock split or other events affecting the holders of Shares (the
"Purchase Price"). Payment shall be made in accordance with Paragraph 9 of the
Plan.

     3.      EXERCISABILITY OF OPTION.

     Subject to the terms and conditions set forth in this Agreement and the
Plan, the Option granted hereby shall become exercisable as follows:

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                                          [TO BE COMPLETED BY COMPANY FOR EACH
                                          PARTICIPANT]

     The foregoing rights are cumulative and are subject to the other terms and
conditions of this Agreement and the Plan.

     4.      TERM OF OPTION.

     The Option shall terminate ten years from the date of this Agreement, but
shall be subject to earlier termination as provided herein or in the Plan.

     If the Participant ceases to be an employee, director or consultant of the
Company or of an Affiliate (for any reason other than the death or Disability of
the Participant or termination of the Participant for "cause" (as defined in the
Plan)), the Option may be exercised, if it has not previously terminated, within
three months after the date the Participant ceases to be an employee, director
or consultant of the Company or an Affiliate, or within the originally
prescribed term of the Option, whichever is earlier, but may not be exercised
thereafter. In such event, the Option shall be exercisable only to the extent
that the Option has become exercisable and is in effect at the date of such
cessation of employment, directorship or consultancy.

     Notwithstanding the foregoing, in the event of the Participant's Disability
or death within three months after the termination of employment, directorship
or consultancy, the Participant or the Participant's Survivors may exercise the
Option within one year after the date of the Participant's termination of
employment, directorship or consultancy, but in no event after the date of
expiration of the term of the Option.

     In the event the Participant's employment, directorship or consultancy is
terminated by the Company or an Affiliate for "cause" (as defined in the Plan),
the Participant's right to exercise any unexercised portion of this Option shall
cease immediately as of the time the Participant is notified his or her
employment, directorship or consultancy is terminated for "cause," and this
Option shall thereupon terminate. Notwithstanding anything herein to the
contrary, if subsequent to the Participant's termination, but prior to the
exercise of the Option, the Board of Directors of the Company determines that,
either prior or subsequent to the Participant's termination, the Participant
engaged in conduct which would constitute "cause," then the Participant shall
immediately cease to have any right to exercise the Option and this Option shall
thereupon terminate.

     In the event of the Disability of the Participant, as determined in
accordance with the Plan, the Option shall be exercisable within one year after
the Participant's termination of service or, if earlier, within the term
originally prescribed by the Option. In such event, the Option shall be
exercisable:

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     (a)     to the extent that the Option has become exercisable but has not
             been exercised as of the date of Disability; and

     (b)     in the event rights to exercise the Option accrue periodically, to
             the extent of a pro rata portion through the date of Disability of
             any additional vesting rights that would have accrued on the next
             vesting date had the Participant not become Disabled. The proration
             shall be based upon the number of days accrued in the current
             vesting period prior to the date of Disability.

     In the event of the death of the Participant while an employee, director or
consultant of the Company or of an Affiliate, the Option shall be exercisable by
the Participant's Survivors within one year after the date of death of the
Participant or, if earlier, within the originally prescribed term of the Option.
In such event, the Option shall be exercisable:

     (x)     to the extent that the Option has become exercisable but has not
             been exercised as of the date of death; and

     (y)     in the event rights to exercise the Option accrue periodically, to
             the extent of a pro rata portion through the date of death of any
             additional vesting rights that would have accrued on the next
             vesting date had the Participant not died. The proration shall be
             based upon the number of days accrued in the current vesting period
             prior to the Participant's date of death.

     5.      METHOD OF EXERCISING OPTION.

     Subject to the terms and conditions of this Agreement, the Option may be
exercised by written notice to the Company or its designee, in substantially the
form of EXHIBIT A attached hereto. Such notice shall state the number of Shares
with respect to which the Option is being exercised and shall be signed by the
person exercising the Option. Payment of the purchase price for such Shares
shall be made in accordance with Paragraph 9 of the Plan. The Company shall
deliver such Shares as soon as practicable after the notice shall be received,
provided, however, that the Company may delay issuance of such Shares until
completion of any action or obtaining of any consent, which the Company deems
necessary under any applicable law (including, without limitation, state
securities or "blue sky" laws). The Shares as to which the Option shall have
been so exercised shall be registered in the Company's share register in the
name of the person so exercising the Option (or, if the Option shall be
exercised by the Participant and if the Participant shall so request in the
notice exercising the Option, shall be registered in the Company's share
register in the name of the Participant and another person jointly, with right
of survivorship) and shall be delivered as provided above to or upon the written
order of the person exercising the Option. In the event the Option shall be
exercised, pursuant to Section 4 hereof, by any person other than the
Participant, such notice shall be accompanied by appropriate proof of the right
of such person to exercise the Option. All Shares that shall be purchased upon
the exercise of the Option as provided herein shall be fully paid and
nonassessable.

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     6.      PARTIAL EXERCISE.

     Exercise of this Option to the extent above stated may be made in part at
any time and from time to time within the above limits, except that no
fractional share shall be issued pursuant to this Option.

     7.      NON-ASSIGNABILITY.

     The Option shall not be transferable by the Participant otherwise than by
will or by the laws of descent and distribution or pursuant to a qualified
domestic relations order as defined by the Code or Title I of the Employee
Retirement Income Security Act or the rules thereunder. Except as provided in
the previous sentence, the Option shall be exercisable, during the Participant's
lifetime, only by the Participant (or, in the event of legal incapacity or
incompetency, by the Participant's guardian or representative) and shall not be
assigned, pledged or hypothecated in any way (whether by operation of law or
otherwise) and shall not be subject to execution, attachment or similar process.
Any attempted transfer, assignment, pledge, hypothecation or other disposition
of the Option or of any rights granted hereunder contrary to the provisions of
this Section 7, or the levy of any attachment or similar process upon the Option
shall be null and void.

     8.      NO RIGHTS AS STOCKHOLDER UNTIL EXERCISE.

     The Participant shall have no rights as a stockholder with respect to
Shares subject to this Agreement until registration of the Shares in the
Company's share register in the name of the Participant. Except as is expressly
provided in the Plan with respect to certain changes in the capitalization of
the Company, no adjustment shall be made for dividends or similar rights for
which the record date is prior to the date of such registration.

     9.      ADJUSTMENTS.

     The Plan contains provisions covering the treatment of Options in a number
of contingencies such as stock splits and mergers. Provisions in the Plan for
adjustment with respect to stock subject to Options and the related provisions
with respect to successors to the business of the Company are hereby made
applicable hereunder and are incorporated herein by reference.

     10.     TAXES.

     The Participant acknowledges that upon exercise of the Option the
Participant will be deemed to have taxable income measured by the difference
between the then fair market value of the Shares received upon exercise and the
price paid for such Shares pursuant to this Agreement. The Participant
acknowledges that any income or other taxes due from him or her with respect to
this Option or the Shares issuable pursuant to this Option shall be the
Participant's responsibility.

     The Participant agrees that the Company may withhold from the Participant's
remuneration, if any, the minimum statutory amount of federal, state and local
withholding taxes attributable to such amount that is considered compensation
includable in such person's gross income. At the Company's discretion, the
amount required to be withheld may be withheld in

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cash from such remuneration, or in kind from the Shares otherwise deliverable to
the Participant on exercise of the Option. The Participant further agrees that,
if the Company does not withhold an amount from the Participant's remuneration
sufficient to satisfy the Company's income tax withholding obligation, the
Participant will reimburse the Company on demand, in cash, for the amount
under-withheld.

     11.     PURCHASE FOR INVESTMENT.

     Unless the offering and sale of the Shares to be issued upon the particular
exercise of the Option shall have been effectively registered under the
Securities Act of 1933, as now in force or hereafter amended (the "1933 Act"),
the Company shall be under no obligation to issue the Shares covered by such
exercise unless and until the following conditions have been fulfilled:

     (a)     The person(s) who exercise the Option shall warrant to the Company,
             at the time of such exercise, that such person(s) are acquiring
             such Shares for their own respective accounts, for investment, and
             not with a view to, or for sale in connection with, the
             distribution of any such Shares, in which event the person(s)
             acquiring such Shares shall be bound by the provisions of the
             following legend which shall be endorsed upon the certificate(s)
             evidencing the Shares issued pursuant to such exercise:

                       "The shares represented by this certificate have been
                       taken for investment and they may not be sold or
                       otherwise transferred by any person, including a pledgee,
                       unless (1) either (a) a Registration Statement with
                       respect to such shares shall be effective under the
                       Securities Act of 1933, as amended, or (b) the Company
                       shall have received an opinion of counsel satisfactory to
                       it that an exemption from registration under such Act is
                       then available, and (2) there shall have been compliance
                       with all applicable state securities laws;" and

     (b)     If the Company so requires, the Company shall have received an
             opinion of its counsel that the Shares may be issued upon such
             particular exercise in compliance with the 1933 Act without
             registration thereunder. Without limiting the generality of the
             foregoing, the Company may delay issuance of the Shares until
             completion of any action or obtaining of any consent, which the
             Company deems necessary under any applicable law (including without
             limitation state securities or "blue sky" laws).

     12.     RESTRICTIONS ON TRANSFER OF SHARES.

     12.1    The Shares acquired by the Participant pursuant to the exercise of
the Option granted hereby shall not be transferred by the Participant except as
permitted herein.

     12.2    In the event of the Participant's termination of service for any
reason, the Company shall have the option, but not the obligation, to repurchase
all or any part of the Shares issued pursuant to this Agreement (including,
without limitation, Shares purchased after termination of employment, Disability
or death in accordance with Section 4 hereof). In the event the Company does
not, upon the termination of service of the Participant (as described

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above), exercise its option pursuant to this Section 12.2, the restrictions set
forth in the balance of this Agreement shall not thereby lapse, and the
Participant for himself or herself, his or her heirs, legatees, executors,
administrators and other successors in interest, agrees that the Shares shall
remain subject to such restrictions. The following provisions shall apply to a
repurchase under this Section 12.2:

     (i)     The per share repurchase price of the Shares to be sold to the
             Company upon exercise of its option under this Section 12.2 shall
             be equal to the Fair Market Value of each such Share determined in
             accordance with the Plan as of the date of termination of service,
             provided, however, in the event of a termination by the Company for
             "cause" (as defined in the Plan), the per share repurchase price of
             the Shares to be sold to the Company upon exercise of its option
             under this Section 12.2 shall be equal to the Purchase Price.

     (ii)    The Company's option to repurchase the Participant's Shares in the
             event of termination of service shall be valid for a period of 18
             months commencing with the date of such termination of service.

     (iii)   In the event the Company shall be entitled to and shall elect to
             exercise its option to repurchase the Participant's Shares under
             this Section 12.2, the Company shall notify the Participant, or in
             case of death, his or her Survivor, in writing of its intent to
             repurchase the Shares. Such written notice may be mailed by the
             Company up to and including the last day of the time period
             provided for in Section 12.2(ii) for exercise of the Company's
             option to repurchase.

     (iv)    The written notice to the Participant shall specify the address at,
             and the time and date on, which payment of the repurchase price is
             to be made (the "Closing"). The date specified shall not be less
             than ten days nor more than 60 days from the date of the mailing of
             the notice, and the Participant or his or her successor in interest
             with respect to the Shares shall have no further rights as the
             owner thereof from and after the date specified in the notice. At
             the Closing, the repurchase price shall be delivered to the
             Participant or his or her successor in interest and the Shares
             being purchased, duly endorsed for transfer, shall, to the extent
             that they are not then in the possession of the Company, be
             delivered to the Company by the Participant or his or her successor
             in interest.

     12.3    It shall be a condition precedent to the validity of any sale or
other transfer of any Shares by the Participant that the following restrictions
be complied with (except as hereinafter otherwise provided):

     (i)     No Shares owned by the Participant may be sold, pledged or
             otherwise transferred (including by gift or devise) to any person
             or entity, voluntarily, or by operation of law, except in
             accordance with the terms and conditions hereinafter set forth.

             (ii)   Before selling or otherwise transferring all or part of the
                    Shares, the Participant shall give written notice of such
                    intention to the Company, which notice shall include the
                    name of the proposed transferee, the proposed purchase price
                    per share, the terms of payment of such purchase

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                    price and all other matters relating to such sale or
                    transfer and shall be accompanied by a copy of the binding
                    written agreement of the proposed transferee to purchase the
                    Shares of the Participant. Such notice shall constitute a
                    binding offer by the Participant to sell to the Company such
                    number of the Shares then held by the Participant as are
                    proposed to be sold in the notice at the monetary price per
                    share designated in such notice, payable on the terms
                    offered to the Participant by the proposed transferee
                    (provided, however, that the Company shall not be required
                    to meet any non-monetary terms of the proposed transfer,
                    including, without limitation, delivery of other securities
                    in exchange for the Shares proposed to be sold). The Company
                    shall give written notice to the Participant as to whether
                    such offer has been accepted in whole by the Company within
                    sixty days after its receipt of written notice from the
                    Participant. The Company may only accept such offer in whole
                    and may not accept such offer in part. Such acceptance
                    notice shall fix a time, location and date for the closing
                    on such purchase ("Closing Date") which shall not be less
                    than ten nor more than sixty days after the giving of the
                    acceptance notice, provided, however, if any of the Shares
                    to be sold pursuant to this Section 12.3 have been held by
                    the Participant for less than six months, then the Closing
                    Date may be extended by the Company until no more than ten
                    days after such Shares have been held by the Participant for
                    six months. The place for such closing shall be at the
                    Company's principal office. At such closing, the Participant
                    shall accept payment as set forth herein and shall deliver
                    to the Company in exchange therefor certificates for the
                    number of Shares stated in the notice accompanied by duly
                    executed instruments of transfer.

     (iii)   If the Company shall fail to accept any such offer, the Participant
             shall be free to sell all, but not less than all, of the Shares set
             forth in his or her notice to the designated transferee at the
             price and terms designated in the Participant's notice, provided
             that (i) such sale is consummated within six months after the
             giving of notice by the Participant to the Company as aforesaid,
             and (ii) the transferee first agrees in writing to be bound by the
             provisions of this Section 12 so that such transferee (and all
             subsequent transferees) shall thereafter only be permitted to sell
             or transfer the Shares in accordance with the terms hereof. After
             the expiration of such six months, the provisions of this Section
             12.3 shall again apply with respect to any proposed voluntary
             transfer of the Participant's Shares.

     (iv)    The restrictions on transfer contained in this Section 12.3 shall
             not apply to (a) transfers by the Participant to his or her spouse
             or children or to a trust for the benefit of his or her spouse or
             children, (b) transfers by the Participant to his or her guardian
             or conservator, and (c) transfers by the Participant, in the event
             of his or her death, to his or her executor(s) or administrator(s)
             or to trustee(s) under his or her will (collectively, "Permitted
             Transferees"); provided however, that in any such event the Shares
             so transferred in the hands of each such Permitted Transferee shall
             remain subject to this Agreement, and each such Permitted
             Transferee shall so acknowledge in writing as a condition precedent
             to the effectiveness of such transfer.

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     (v)     The provisions of this Section 12.3 may be waived by the Company.
             Any such waiver may be unconditional or based upon such conditions
             as the Company may impose.

     12.4    In the event that the Participant or his or her successor in
interest fails to deliver the Shares to be repurchased by the Company under this
Agreement, the Company may elect (a) to establish a segregated account in the
amount of the repurchase price, such account to be turned over to the
Participant or his or her successor in interest upon delivery of such Shares,
and (b) immediately to take such action as is appropriate to transfer record
title of such Shares from the Participant to the Company and to treat the
Participant and such Shares in all respects as if delivery of such Shares had
been made as required by this Agreement. The Participant hereby irrevocably
grants the Company a power of attorney which shall be coupled with an interest
for the purpose of effectuating the preceding sentence.

     12.5    If the Company shall pay a stock dividend or declare a stock split
on or with respect to any of its Common Stock, or otherwise distribute
securities of the Company to the holders of its Common Stock, the number of
shares of stock or other securities of Company issued with respect to the shares
then subject to the restrictions contained in this Agreement shall be added to
the Shares subject to the Company's rights to repurchase pursuant to this
Agreement. If the Company shall distribute to its stockholders shares of stock
of another corporation, the shares of stock of such other corporation,
distributed with respect to the Shares then subject to the restrictions
contained in this Agreement, shall be added to the Shares subject to the
Company's rights to repurchase pursuant to this Agreement.

     12.6    If the outstanding shares of Common Stock of the Company shall be
subdivided into a greater number of shares or combined into a smaller number of
shares, or in the event of a reclassification of the outstanding shares of
Common Stock of the Company, or if the Company shall be a party to a merger,
consolidation or capital reorganization, there shall be substituted for the
Shares then subject to the restrictions contained in this Agreement such amount
and kind of securities as are issued in such subdivision, combination,
reclassification, merger, consolidation or capital reorganization in respect of
the Shares subject immediately prior thereto to the Company's rights to
repurchase pursuant to this Agreement.

     12.7    The Company shall not be required to transfer any Shares on its
books which shall have been sold, assigned or otherwise transferred in violation
of this Agreement, or to treat as owner of such Shares, or to accord the right
to vote as such owner or to pay dividends to, any person or organization to
which any such Shares shall have been so sold, assigned or otherwise
transferred, in violation of this Agreement.

     12.8    The provisions of Sections 12.1, 12.2 and 12.3 shall terminate upon
the effective date of the registration of the Shares pursuant to the Securities
Exchange Act of 1934.

     12.9    If, in connection with a registration statement filed by the
Company pursuant to the 1933 Act, the Company or its underwriter so requests,
the Participant will agree not to sell any Shares for a period not to exceed 180
days following the effectiveness of such registration.

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     12.10   The Participant acknowledges and agrees that neither the Company,
its shareholders nor its directors and officers, has any duty or obligation to
disclose to the Participant any material information regarding the business of
the Company or affecting the value of the Shares before, at the time of, or
following a termination of the employment of the Participant by the Company,
including, without limitation, any information concerning plans for the Company
to make a public offering of its securities or to be acquired by or merged with
or into another firm or entity.

     12.11   All certificates representing the Shares to be issued to the
Participant pursuant to this Agreement shall have endorsed thereon a legend
substantially as follows: "The shares represented by this certificate are
subject to restrictions set forth in a Non-Qualified Stock Option Agreement
dated ________, 200__ with this Company, a copy of which Agreement is available
for inspection at the offices of the Company or will be made available upon
request."

     13.     NO OBLIGATION TO MAINTAIN RELATIONSHIP.

     The Company is not by the Plan or this Option obligated to continue the
Participant as an employee, director or consultant of the Company or an
Affiliate. The Participant acknowledges: (i) that the Plan is discretionary in
nature and may be suspended or terminated by the Company at any time; (ii) that
the grant of the Option is a one-time benefit which does not create any
contractual or other right to receive future grants of options, or benefits in
lieu of options; (iii) that all determinations with respect to any such future
grants, including, but not limited to, the times when options shall be granted,
the number of shares subject to each option, the option price, and the time or
times when each option shall be exercisable, will be at the sole discretion of
the Company; (iv) that the Participant's participation in the Plan is voluntary;
(v) that the value of the Option is an extraordinary item of compensation which
is outside the scope of the Participant's employment contract, if any; and (vi)
that the Option is not part of normal or expected compensation for purposes of
calculating any severance, resignation, redundancy, end of service payments,
bonuses, long-service awards, pension or retirement benefits or similar
payments.

     14.     NOTICES.

     Any notices required or permitted by the terms of this Agreement or the
Plan shall be given by recognized courier service, facsimile, registered or
certified mail, return receipt requested, addressed as follows:

If to the Company:

             Metabolix, Inc.
             21 Erie Street
             Cambridge, MA 02139-4260
             Attention:

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If to the Participant:

                              ---------------------------------------

                              ---------------------------------------

                              ---------------------------------------

or to such other address or addresses of which notice in the same manner has
previously been given. Any such notice shall be deemed to have been given upon
the earlier of receipt, one business day following delivery to a recognized
courier service or three business days following mailing by registered or
certified mail.

     15.     GOVERNING LAW.

     This Agreement shall be construed and enforced in accordance with the law
of the State of Delaware, without giving effect to the conflict of law
principles thereof. For the purpose of litigating any dispute that arises under
this Agreement, the parties hereby consent to exclusive jurisdiction in the
Commonwealth of Massachusetts and agree that such litigation shall be conducted
in the courts of Middlesex County, Massachusetts or the federal courts of the
United States for the District of Massachusetts.

     16.     BENEFIT OF AGREEMENT.

     Subject to the provisions of the Plan and the other provisions hereof, this
Agreement shall be for the benefit of and shall be binding upon the heirs,
executors, administrators, successors and assigns of the parties hereto.

     17.     ENTIRE AGREEMENT.

     This Agreement, together with the Plan, embodies the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior oral or written agreements and understandings
relating to the subject matter hereof. No statement, representation, warranty,
covenant or agreement not expressly set forth in this Agreement shall affect or
be used to interpret, change or restrict, the express terms and provisions of
this Agreement, provided, however, in any event, this Agreement shall be subject
to and governed by the Plan.

     18.     MODIFICATIONS AND AMENDMENTS.

     The terms and provisions of this Agreement may be modified or amended as
provided in the Plan.

     19.     WAIVERS AND CONSENTS.

     Except as provided in the Plan, the terms and provisions of this Agreement
may be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in

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the specific instance and for the purpose for which it was given, and shall not
constitute a continuing waiver or consent.

     20.     DATA PRIVACY.

     By entering into this Agreement, the Participant: (i) authorizes the
Company and each Affiliate, and any agent of the Company or any Affiliate
administering the Plan or providing Plan recordkeeping services, to disclose to
the Company or any of its Affiliates such information and data as the Company or
any such Affiliate shall request in order to facilitate the grant of options and
the administration of the Plan; (ii) waives any data privacy rights he or she
may have with respect to such information; and (iii) authorizes the Company and
each Affiliate to store and transmit such information in electronic form.

     21.     CONSENT OF SPOUSE.

     If the Participant is married as of the date of this Agreement, the
Participant's spouse shall execute a Consent of Spouse in the form of EXHIBIT B
hereto, effective as of the date hereof. Such consent shall not be deemed to
confer or convey to the spouse any rights in the Shares that do not otherwise
exist by operation of law or the agreement of the parties. If the Participant
marries or remarries subsequent to the date hereof, the Participant shall, not
later than 60 days thereafter, obtain his or her new spouse's acknowledgement of
and consent to the existence and binding effect of Section 12.2 of this
Agreement by such spouse's executing and delivering a Consent of Spouse in the
form of Exhibit B.

                  [Remainder of Page Intentionally Left Blank]

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     IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by
its duly authorized officer, and the Participant has hereunto set his or her
hand, all as of the day and year first above written.

                                           METABOLIX, INC.

                                           By:
                                              ----------------------------------
                                              Name:
                                              Title:

                                           -------------------------------------
                                              Participant

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                                                                       EXHIBIT A

                NOTICE OF EXERCISE OF NON-QUALIFIED STOCK OPTION

                         [FORM FOR UNREGISTERED SHARES]

To:  Metabolix, Inc.

Ladies and Gentlemen:

     I hereby exercise my Non-Qualified Stock Option to purchase __________
shares (the "Shares") of the common stock, $.01 par value, of Metabolix, Inc.
(the "Company"), at the exercise price of $_____ per share, pursuant to and
subject to the terms of that certain Non-Qualified Stock Option Agreement
between the undersigned and the Company dated ________, 200_.

     I am aware that the Shares have not been registered under the Securities
Act of 1933, as amended (the "1933 Act"), or any state securities laws. I
understand that the reliance by the Company on exemptions under the 1933 Act is
predicated in part upon the truth and accuracy of the statements by me in this
Notice of Exercise.

     I hereby represent and warrant that (1) I have been furnished with all
information which I deem necessary to evaluate the merits and risks of the
purchase of the Shares; (2) I have had the opportunity to ask questions
concerning the Shares and the Company and all questions posed have been answered
to my satisfaction; (3) I have been given the opportunity to obtain any
additional information I deem necessary to verify the accuracy of any
information obtained concerning the Shares and the Company; and (4) I have such
knowledge and experience in financial and business matters that I am able to
evaluate the merits and risks of purchasing the Shares and to make an informed
investment decision relating thereto.

     I hereby represent and warrant that I am purchasing the Shares for my own
personal account for investment and not with a view to the sale or distribution
of all or any part of the Shares.

     I understand that because the Shares have not been registered under the
1933 Act, I must continue to bear the economic risk of the investment for an
indefinite time and the Shares cannot be sold unless the Shares are subsequently
registered under applicable federal and state securities laws or an exemption
from such registration requirements is available.

     I agree that I will in no event sell or distribute or otherwise dispose of
all or any part of the Shares unless (1) there is an effective registration
statement under the 1933 Act and applicable state securities laws covering any
such transaction involving the Shares or (2) the Company receives an opinion of
my legal counsel (concurred in by legal counsel for the

                                       A-1
<Page>

Company) stating that such transaction is exempt from registration or the
Company otherwise satisfies itself that such transaction is exempt from
registration.

     I consent to the placing of a legend on my certificate for the Shares
stating that the Shares have not been registered and setting forth the
restriction on transfer contemplated hereby and to the placing of a stop
transfer order on the books of the Company and with any transfer agents against
the Shares until the Shares may be legally resold or distributed without
restriction.

     I understand that at the present time Rule 144 of the Securities and
Exchange Commission (the "SEC") may not be relied on for the resale or
distribution of the Shares by me. I understand that the Company has no
obligation to me to register the sale of the Shares with the SEC and has not
represented to me that it will register the sale of the Shares.

     I understand the terms and restrictions on the right to dispose of the
Shares set forth in the 2004 Employee, Director and Consultant Stock Plan and
the Non-Qualified Stock Option Agreement, both of which I have carefully
reviewed. I consent to the placing of a legend on my certificate for the Shares
referring to such restriction and the placing of stop transfer orders until the
Shares may be transferred in accordance with the terms of such restrictions.

     I have considered the Federal, state and local income tax implications of
the exercise of my Option and the purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                                   ----------

     Please issue the stock certificate for the Shares (check one):

     / / to me; or

     / / to me and ________________, as joint tenants with right of survivorship

and mail the certificate to me at the following address:

----------------------------

----------------------------

----------------------------

     My mailing address for shareholder communications, if different from the
address listed above is:

                                       A-2
<Page>

----------------------------

----------------------------

----------------------------

                                       Very truly yours,

                                       -----------------------------------------
                                       Participant (signature)

                                       -----------------------------------------
                                       Print Name

                                       -----------------------------------------
                                       Date

                                       -----------------------------------------
                                       Social Security Number

                                      A-3
<Page>

                                                                       EXHIBIT A

                NOTICE OF EXERCISE OF NON-QUALIFIED STOCK OPTION

IMPORTANT NOTICE: This form of Notice of Exercise may only be used at such time
as the Company has filed a Registration Statement with the Securities and
Exchange Commission under which the issuance of the Shares for which this
exercise is being made is registered and such Registration Statement remains
effective.

TO:  Metabolix, Inc.

Ladies and Gentlemen:

     I hereby exercise my Non-Qualified Stock Option to purchase _________
shares (the "Shares") of the common stock, $.01 par value, of Metabolix, Inc.
(the "Company"), at the exercise price of $________ per share, pursuant to and
subject to the terms of that certain Non-Qualified Stock Option Agreement
between the undersigned and the Company dated _______________, 200_.

     I understand the nature of the investment I am making and the financial
risks thereof. I am aware that it is my responsibility to have consulted with
competent tax and legal advisors about the relevant national, state and local
income tax and securities laws affecting the exercise of the Option and the
purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                                   ----------

     Please issue the Shares (check one):

     / / to me; or

     / / to me and____________________________, as joint tenants with right of
                   survivorship,

     at the following address:

     ----------------------------------

     ----------------------------------

     ----------------------------------

                                       A-1
<Page>

     My mailing address for shareholder communications, if different from the
address listed above, is:

     --------------------------------------------

     --------------------------------------------

     --------------------------------------------

                                       Very truly yours,

                                       -----------------------------------------
                                        Participant (signature)

                                       -----------------------------------------
                                        Print Name

                                       -----------------------------------------
                                        Date

                                       -----------------------------------------
                                        Social Security Number

                                      A-2
<Page>

                                                                       EXHIBIT B

                                CONSENT OF SPOUSE

     I, ____________________________, spouse of _____________________________,
acknowledge that I have read the Non-Qualified Stock Option Agreement dated as
of _______________, 200__ (the "Agreement") to which this Consent is attached as
Exhibit B and that I know its contents. Capitalized terms used and not defined
herein shall have the meanings assigned to such terms in the Agreement. I am
aware that by its provisions the Shares granted to my spouse pursuant to the
Agreement are subject to a right of repurchase in favor of Metabolix, Inc. (the
"Company") and that, accordingly, the Company has the right to repurchase up to
all of the Shares of which I may become possessed as a result of a gift from my
spouse or a court decree and/or any property settlement in any domestic
litigation.

     I hereby agree that my interest, if any, in the Shares subject to the
Agreement shall be irrevocably bound by the Agreement and further understand and
agree that any community property interest I may have in the Shares shall be
similarly bound by the Agreement.

     I agree to the repurchase right described in Section 12.2 of the Agreement
and I hereby consent to the repurchase of the Shares by the Company and the sale
of the Shares by my spouse or my spouse's legal representative in accordance
with the provisions of the Agreement. Further, as part of the consideration for
the Agreement, I agree that at my death, if I have not disposed of any interest
of mine in the Shares by an outright bequest of the Shares to my spouse, then
the Company shall have the same rights against my legal representative to
exercise its rights of repurchase with respect to any interest of mine in the
Shares as it would have had pursuant to the Agreement if I had acquired the
Shares pursuant to a court decree in domestic litigation.

     I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE
AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT PROFESSIONAL
GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH
GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I
WILL WAIVE SUCH RIGHT.

     Dated as of the _______ day of ________________, 200__.

                                    --------------------------------------------
                                    Print name:

                                      B-1<Page>

                                                                   Exhibit 10.15

                                                                  EXECUTION COPY

                                METABOLIX, INC.
                    21 ERIE STREET, CAMBRIDGE, MASSACHUSETTS

<Page>

                                TABLE OF CONTENTS

<Table>
<Caption>
                                                                              PAGE
<S>                                                                             <C>
ARTICLE 1: BASIC TERMS...........................................................1
ARTICLE 2: PREMISES AND APPURTENANT RIGHTS.......................................6
  2.01  Lease of Premises; Appurtenant Rights....................................6
ARTICLE 3: LEASE TERM............................................................8
  3.01  Lease Term; Delay in Commencement........................................8
  3.02  Hold Over................................................................8
  3.03  Right to Extend..........................................................9
  3.04  Early Termination Right.................................................11
ARTICLE 4: RENT.................................................................13
  4.01  Base Rent...............................................................13
  4.02  Additional Rent.........................................................13
  4.03  Late Charge.............................................................15
  4.04  Interest................................................................15
  4.05  Method of Payment.......................................................15
  4.06  Tenant's Pro Rata Share.................................................16
ARTICLE 5: TAXES................................................................16
  5.01  Taxes...................................................................16
  5.02  Definition of "Taxes"...................................................16
  5.03  Personal Property Taxes.................................................17
ARTICLE 6: UTILITIES............................................................17
  6.01  Utilities and Common Facilities.........................................17
ARTICLE 7: INSURANCE............................................................18
  7.01  Coverage................................................................18
  7.02  Avoid Action Increasing Rates...........................................19
  7.03  Waiver of Subrogation...................................................19
  7.04  Landlord's Insurance....................................................19
ARTICLE 8: COMMON EXPENSES......................................................20
  8.01  Operating Expenses......................................................20
</Table>

<Page>

<Table>
<S>                                                                             <C>
ARTICLE 9: USE OF PREMISES......................................................21
  9.01  Permitted Uses..........................................................21
  9.02  Indemnification.........................................................21
  9.03  Compliance With Legal Requirements......................................22
  9.04  Environmental Substances................................................23
  9.05  Signs and Auctions......................................................25
  9.06  Landlord's Access.......................................................25
ARTICLE 10: CONDITION AND MAINTENANCE OF PREMISES AND PROPERTY..................26
  10.01 Existing Conditions.....................................................26
  10.02 Exemption and Limitation of Landlord's Liability........................26
  10.03 Landlord's Obligations..................................................27
  10.04 Tenant's Obligations....................................................27
  10.05 Tenant Work.............................................................28
  10.06 Condition upon Termination..............................................32
  10.07 Decommissioning of the Premises.........................................33
ARTICLE 11: ROOFTOP LICENSE.....................................................34
  11.01 Rooftop License.........................................................34
  11.02 Installation and Maintenance of Rooftop Equipment.......................35
  11.03 Indemnification.........................................................35
  11.04 Removal of Antenna......................................................35
  11.05 Interference by Antenna.................................................36
  11.06 Relocation of Antennas .................................................37
ARTICLE 12: DAMAGE OR DESTRUCTION; CONDEMNATION.................................37
  12.01 Damage or Destruction of Premises.......................................37
  12.02 Eminent Domain..........................................................39
ARTICLE 13: ASSIGNMENT AND SUBLETTING...........................................39
  13.01 Landlord's Consent Required.............................................40
  13.02 Terms...................................................................40
  13.03 Right of Termination or Recapture.......................................40
  13.04 Procedures..............................................................41
</Table>

                                     - ii -
<Page>

<Table>
<S>                                                                             <C>
  13.05 Excess Rents............................................................4l
  13.06 No Release..............................................................42
  13.07 Termination Upon Assignment.............................................43
ARTICLE 14: EVENTS OF DEFAULT AND REMEDIES......................................43
  14.01 Events of Default.......................................................43
  14.02 Remedies for Default....................................................45
ARTICLE 15: SECURITY DEPOSIT....................................................47
  15.01 Security Deposit........................................................47
ARTICLE 16: PROTECTION OF LENDERS/GROUND LANDLORD...............................49
  16.01 Subordination and Superiority of Lease..................................49
  16.02 Rent Assignment.........................................................50
  16.03 Other Instruments.......................................................50
  16.04 Estoppel Certificates...................................................50
  16.05 Financial Condition.....................................................5l
ARTICLE 17: MISCELLANEOUS PROVISIONS ...........................................5l
  17.01 Landlord's Consent Fees.................................................51
  17.02 Notice of Landlord's Default............................................51
  l7.03 Quiet Enjoyment.........................................................52
  17.04 Interpretation..........................................................52
  17.05 Notices.................................................................52
  17.06 No Recordation..........................................................52
  17.07 Corporate Authority.....................................................52
  17.08 Joint and Several Liability, Counterparts...............................53
  17.09 Force Majeure...........................................................53
  17.10 Limitation of Warranties................................................53
  17.11 No Other Brokers........................................................53
  17.12 Applicable Law and Construction.........................................53
ARTICLE 18: EXPANSION RIGHTS....................................................54
  18.1  Right of First Offer....................................................54
</Table>

                                     - iii -
<Page>
                                    EXHIBITS

<Table>
<S>                                                                             <C>
EXHIBIT A - PROPERTY............................................................58
EXHIBIT B - PREMISES............................................................60
EXHIBIT C - FORM OF LETTER OF CREDIT............................................61
EXHIBIT D - FORM OF CONFIRMATION OF DELIVERY DATE...............................63
EXHIBIT E - RULES AND REGULATIONS...............................................64
EXHIBIT F - ENVIRONMENTAL SUBSTANCES............................................66
EXHIBIT G - CONSTRUCTION DOCUMENTS..............................................67
EXHIBIT H - TENANT WORK INSURANCE SCHEDULE......................................72
EXHIBIT H-1 - TENANT CONTRACTOR AND SUBCONTRACTOR INSURANCE
LIMIT REQUIREMENTS..............................................................75
EXHIBIT I - BASE BUILDING WORK..................................................80
EXHIBIT J - TENANT RELATED WORK.................................................81
EXHIBIT K - INTENTIONALLY OMITTED.................................................
EXHIBIT L - FINISH WORK LETTER..................................................82
EXHIBIT M - INITIAL WARRANT.....................................................87
EXHIBIT N - FIRST OFFER SPACE...................................................88
EXHIBIT O - TERMINATION PAYMENT EXAMPLE.........................................89
EXHIBIT P - STANDARD FORM OF CONSENT TO A SUBLEASE..............................90
</Table>

                                     - iv -
<Page>

                                METABOLIX, INC.

                    21 ERIE STREET, CAMBRIDGE, MASSACHUSETTS

ARTICLE 1: BASIC TERMS

The following terms used in this Lease shall have the meanings set forth below.

DATE OF LEASE:                  As of December 29, 2003

LANDLORD                        21 Erie Realty Trust

TENANT                          Metabolix, Inc., a Delaware corporation

GUARANTOR:                      Not Applicable.

ADDRESS OF PROPERTY:            21 Erie Street, Cambridge, Massachusetts.

BUILDING AND PROPERTY:          The two story building containing approximately
                                48,627 rentable square feet ("BUILDING") in the
                                City of Cambridge, Massachusetts, located on a
                                parcel of land described in EXHIBIT A (the
                                Building and such parcel of land being
                                collectively referred to as the "PROPERTY").

PREMISES:                       28,019 rentable square feet, consisting of
                                26,422 rentable square feet on the second floor
                                of the Building (being all of the second floor)
                                and 1,597 rentable square feet on the first
                                floor of the building, each located as
                                described in EXHIBIT B.

TENANT'S PRO RATA SHARE:        57.6%

TERM:

     Initial Term:              Ten (10) Lease Years from the Commencement
                                Date.

     Extension Term:            Two (2) extension terms of five (5) Lease
                                Years.

     Lease Year:                The first Lease Year begins at 12:01 a.m. on
                                the Term Commencement Date and ends at 11:59
                                p.m. on the last day of the twelfth full
                                calendar month after said Term Commencement
                                Date. Each subsequent Lease Year ends at 11:59
                                p.m. twelve months after the

<Page>

                                preceding one Lease Year.

     Estimated Delivery Date:   March 15, 2004

     Term Commencement Date:    The Delivery Date as set forth in Section 3.01.

     Rent Commencement Date:    The earlier of (a) two months after the
                                Delivery Date (e.g. May 1, 2004, if the Delivery
                                Date occurs on March 1, 2004) or (b) two months
                                after the date upon which Tenant first occupies
                                all or any portion of the Premises for the
                                conduct of its business (e.g. April 15, 2004 if
                                Tenant occupies a portion of the Premises for
                                the conduct of its business on February 15,
                                2004).

PERMITTED USES:                 Technical office for research and development,
                                laboratory and research facility, and, as an
                                ancillary use, limited manufacturing activity
                                to the extent permitted under applicable zoning
                                laws.

BROKER(S):                      Richards Barry Joyce & Partners, LLC for the
                                Tenant  and CBRE Lynch Murphy Walsh Advisors for
                                the Landlord.

MANAGEMENT COMPANY:             Hallkeen Management Group

SECURITY DEPOSIT:               $493,975 in the form of cash or an irrevocable
                                Letter of Credit as set forth in ARTICLE 15.

                                      - 2 -
<Page>

PARKING:                        28 parking spaces as set forth in Section
                                2.01(e) at the rate of one (1) parking space(s)
                                per 1,000 rentable square feet of the Premise.

BASE RENT:

     Initial Term:              $756,513 per annum ($27.00 per rentable square
                                foot of the Premises), increased annually
                                effective on the first day of each Lease Year
                                to reflect increases, if any, on account of the
                                CPI Adjustment as defined and described in
                                Section 3.03(d).

     Extension Term:            Base Rent per annum shall be the greater of (x)
                                Market Rent, as determined pursuant to Section
                                3.03, or (y) the Base Rent immediately prior to
                                the Extension Term as adjusted at the beginning
                                of the Extension Term by the CPI Adjustment;
                                but Base Rent in an Extension Term shall never
                                be less than Base Rent paid in the Lease Year
                                immediately prior to such Extension Term.

ADDITIONAL RENT:                All amounts payable by Tenant under this Lease
                                other than Base Rent, including: Tenant's Pro
                                Rata Share of Taxes (Article 5), utilities
                                (Article 6), insurance premiums (Article 7) and
                                other Operating Expenses (Article 8). (See
                                Section 4.02)

ORIGINAL ADDRESS OF LANDLORD:   21 Erie Realty Trust
                                c/o Lyme Properties, LLC
                                101 Main Street, 18th Floor
                                Cambridge, MA 02142
                                Attn: David Clem and Robert L. Green

                                With copies to:

                                Piper Rudnick LLP
                                One International Place
                                21st Floor
                                Boston, MA 02110
                                Attn: Greg D. Peterson, Esq.

ORIGINAL ADDRESS OF TENANT:     Before Delivery Date:

                                Metabolix, Inc.

                                      - 3 -
<Page>

                                303 Third Street
                                Cambridge, MA 02142
                                Attn: President

                                After Delivery Date:

                                At the Premises, Attn: President

                                With copies to:

                                Testa, Hurwitz & Thibeault, LLP
                                125 High Street
                                Boston, MA 02110
                                Attn: Douglas M. Henry, Esq.

BASE BUILDING WORK:             As set forth in Section 10.03(a)

TENANT RELATED WORK             As set forth in Section 10.03(a)

EXHIBITS:                       Exhibit A:   Property
                                Exhibit B:   Premises
                                Exhibit C:   Form of Letter of Credit
                                Exhibit D:   Form of Confirmation of Delivery
                                             Date
                                Exhibit E:   Rules and Regulations
                                Exhibit F:   Environmental Substances
                                Exhibit G:   Construction Document Requirements
                                Exhibit H:   Tenant Work Insurance Schedule
                                Exhibit H-1: Tenant Contractor and Subcontractor
                                             Insurance Limit Requirements
                                Exhibit I:   Base Building Work
                                Exhibit J:   Tenant Related Work
                                Exhibit K:   Intentionally Omitted
                                Exhibit L:   Finish Work Letter
                                Exhibit M:   Initial Warrant
                                Exhibit N:   First Offer Space
                                Exhibit O:   Termination Payment Example
                                Exhibit P:   Standard Form of Consent to a
                                             Sublease

                                      - 4 -
<Page>

                         LIST OF CERTAIN DEFINED TERMS

AAA........................................................................11.05
Additional Rent........................................................Article 1
Adjustment...............................................................3.03(d)
Administrative Charge...................................................14.02(f)
Arbitrator...............................................................3.03(c)
Base Building Work......................................................10.03(a)
Base Price Index.........................................................3.03(d)
Construction Documents..................................................10.05(b)
Coordination Schedule...............................................Section L.10
Core Building Systems...................................................10.05(a)
CPI......................................................................3.03(d)
CPI Adjustment...........................................................3.03(d)
Delivery Date...............................................................3.01
Dissolution Termination Date...............................................13.07
Early Termination Date......................................................3.04
Environmental Law...........................................................9.04
Environmental Substances....................................................9.04
Event of Default...........................................................14.01
Extension Term...........................................................3.03(a)
Finish Work.............................................................10.04(c)
Indemnitees.................................................................9.02
Initial Warrant............................................................14.01
Lease..................................................................Exhibit D
Legal Requirement...........................................................9.03
Letter of Credit...........................................................15.01
Market Rent..............................................................3.03(c)
Merger/Sale Termination Notice.............................................13.07
Mortgage...................................................................16.01
Mortgagee..................................................................16.01
Non-monetary Default.......................................................17.12
Operating Costs..........................................................4.02(a)
Operating Expenses..........................................................8.01
Related Party Transfer.....................................................13.04
Reletting Expenses......................................................14.02(a)
Rent.....................................................................4.02(a)
Rooftop Installation Areas.................................................11.01
Special Costs..........................................................10.07(ii)
Special Procedures.....................................................10.07(ii)
Tenant Contractor.......................................................10.05(c)
Tenant Property............................................................10.06
Tenant's Architect......................................................10.05(b)

                                      - 5 -
<Page>

Tenant's Equipment.........................................................11.01
Term.......................................................................17.12
Termination Notice..........................................................3.04
Termination Payment.........................................................3.04
Third Arbitrator.........................................................3.03(c)
Total Operating Costs....................................................4.02(a)
Transfer...................................................................13.01
Transfer Expenses..........................................................13.05
Transferee.................................................................13.01
Utility Service.............................................................6.01
Utility Service Provider....................................................6.01
Utility Switching Points ...................................................6.01
Warrant....................................................................14.01

ARTICLE 2: PREMISES AND APPURTENANT RIGHTS

2.01 LEASE OF PREMISES; APPURTENANT RIGHTS. Landlord hereby leases the Premises
to Tenant, and Tenant hereby leases the Premises from Landlord, for the Term.
Subject to Landlord's reasonable rules of general applicability from time to
time adopted and of which Tenant is given notice, Tenant shall have access to
the Premises twenty-four (24) hours a day, seven (7) days a week. Landlord's
initial rules are set forth in Exhibit E.

     (a) EXCLUSIONS. The Premises exclude common areas and facilities of the
Property, including without limitation exterior faces of exterior walls, the
common stairways and stairwells, entranceways and the main lobby, elevators and
elevator wells, fan rooms, electric and telephone closets, janitor closets,
freight elevator vestibules, and pipes, ducts, conduits, wires and appurtenant
fixtures serving other parts of the Property (exclusively or in common) and
other common areas and facilities from time to time designated as such by
Landlord. If the Premises include less than the entire rentable area of any
floor, then the Premises also exclude the common corridors, elevator lobby and
toilets located on such floor.

     (b) APPURTENANT RIGHTS. Tenant shall have, as appurtenant to the Premises,
rights to use in common with others (subject to reasonable rules of general
applicability of which Tenant is given notice) the common areas and facilities
of the Property.

     (c) RESERVATIONS. In addition to other rights reserved herein or by law,
Landlord reserves the right from time to time, without unreasonable (except in
emergency) interruption of Tenant's use: (i) to make additions to or
reconstructions of the Building (including without limitation the Base Building
Work and tenant improvements in other premises within the Building) and 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, the Building, or

                                      - 6 -
<Page>

elsewhere in the Property; (ii) to alter or relocate any other common area or
facility, including the drives, lobbies and entrances and (iii) to grant
easements and other rights with respect to the Property. Installations,
replacements and relocations within the Premises referred to in clause (i) shall
be located as far as practicable in the core areas of the Building, above
ceiling surfaces, below floor surfaces or within perimeter walls of the
Premises. Alterations, relocations or grants referred to in clauses (ii) and
(iii) above shall neither have a material adverse effect on Tenant's access to
the Premises, nor increase Tenant's Pro Rata Share. This Lease, and Tenant's
leasehold interest in the Premises, are subject to, and with the benefit of, the
terms, covenants and conditions of this Lease, and rights, agreements, easements
and restrictions of record applicable to the Property, all of which Tenant shall
perform and observe insofar as the same are applicable to the Premises;
provided, however, that Tenant shall not be bound by any easements or
restrictions made after the date of this Lease that materially affect Tenant's
rights and obligations under this Lease unless and until Landlord has obtained
Tenant's prior written consent thereto, which shall not be unreasonably
withheld, conditioned or delayed. Landlord hereby represents and warrants that
none of the existing agreements, easements and restrictions of record prohibit
or restrict use of the Demised Premises for the Permitted Uses.

     Landlord further reserves the right to develop additions and other
improvements at the Property as it may determine in its discretion. This may
entail subdivision of the Property, a separate ground lease of a portion of the
Property, or creation of a condominium in a manner that allows development of
any addition or other improvements as an independent project. This Lease shall
be subject and subordinate to any such subdivision, ground lease, or condominium
(and covenants and easements granted in connection therewith) so long as the
same are not inconsistent in any material respect with Tenant's rights under
this Lease or would not result in any increase in Tenant's Pro Rata Share.

     Tenant agrees not to take any action to hinder or oppose any additional
development at the Property proposed by Landlord so long as such additional
development is not inconsistent in any material respect with Tenant's rights
under this Lease or would result in an increase in Tenant's Pro Rata Share.

     (d) PARKING. During the Term, Landlord shall provide Tenant with one
parking pass for each of the number of parking spaces set forth in Article 1 for
use at the garage located on the Property. Use of the parking spaces shall be on
a non-exclusive, non-reserved basis. Tenant shall pay for such parking passes
to such spaces (whether or not so used) at the then current prevailing monthly
rate for garage parking spaces in the area, as reasonably determined by the
Landlord from time to time. The current monthly rate for such parking is $200
per month per space. Such payments shall constitute Additional Rent for purposes
of the Lease. Payments under this Section shall be made at the places and times
and subject to the conditions specified for payments of Base Rent, or at such
other places and times as Landlord shall specify in writing. To the extent
applicable to Tenant's

                                      - 7 -
<Page>

use of the parking spaces, the provisions of the Lease shall apply, including
rules and regulations of general applicability from time to time promulgated by
Landlord. Without limiting Landlord's other remedies under the Lease, if Tenant
shall fail to pay the amounts due for such parking spaces for more than ten (10)
days after written notice of such failure more than once in a twelve-month
period, then Landlord may terminate Tenant's rights to such spaces immediately
upon notice by Landlord.

     The parking passes shall not be assigned or sublicensed except in
connection with a Transfer permitted under Article 13. Tenant acknowledges that
Landlord has informed Tenant that the parking garage may be available for
transient parking and that, for the purpose of maximizing usage of the facility,
Landlord may allocate in its tenant leases more than the actual parking spaces
anticipated to be available to the Property. It is further acknowledged and
agreed that as a consequence of such over-allocation of parking spaces and/or
transient usage, there may occasionally occur instances in which the number of
parking spaces actually available to Tenant shall be less than the Parking
Spaces to which Tenant is entitled under this Lease. Landlord shall incur no
liability to Tenant as a consequence of such events; provided, however, that if
any passholder is denied entry to the parking garage more than two times in any
calendar month, and further provided that Tenant gives written notice to
Landlord within five days of each such occurrence, Landlord will refund one
month's then-current parking space fee to Tenant.

ARTICLE 3: LEASE TERM

3.01   LEASE TERM; DELAY IN DELIVERY DATE. The Initial Term of this Lease is set
forth in Article 1. Landlord shall use reasonable efforts to substantially
complete the Tenant Related Work and deliver the Premises to Tenant on or before
the Estimated Delivery Date. The "DELIVERY DATE" shall mean the date that
Landlord delivers to Tenant a certificate of Landlord's architect stating that
the Tenant Related Work is substantially complete, but in any event shall be no
earlier than March 1, 2004. Promptly after the Delivery Date, Landlord and
Tenant shall execute and deliver a Confirmation of Delivery Date in the form of
EXHIBIT D, but Rent shall commence on the Rent Commencement Date whether or not
such confirmation is executed. Landlord's failure to deliver the Premises to
Tenant on or before the Estimated Delivery Date, for any reason, shall not give
rise to any liability of Landlord hereunder, shall not constitute a Landlord's
default, shall not affect the validity of this Lease, and shall have no effect
on the beginning or end of the Term as otherwise determined hereunder or on
Tenant's obligations associated therewith, but Tenant shall only commence paying
Rent on the Rent Commencement Date.

3.02   HOLD OVER. If Tenant (or anyone claiming through Tenant) shall remain in
occupancy of the Premises or any part thereof after the expiration or early
termination of the Term without a written agreement therefor executed and
delivered by Landlord, then without limiting Landlord's other rights and
remedies the person remaining in possession shall be deemed a tenant at
sufferance, and Tenant shall thereafter pay monthly rent (pro

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rated for such portion of any partial month as Tenant shall remain in
possession) at a rate equal to the greater of (a) 125% of the fair market rent
then being quoted by Landlord for the Premises or comparable space in the
Building, or (b) 150% of the amount payable as Base Rent for the 12-month period
immediately preceding such expiration or termination, and in either case with
all Additional Rent also payable as provided in this Lease. After Landlord's
acceptance of the full amount of such rent for the first month of such holding
over, the person remaining in possession shall be deemed a tenant at will at
such rent and otherwise subject to all of the provisions of this Lease.
Notwithstanding the foregoing, if Landlord desires to regain possession of the
Premises promptly after the termination or expiration hereof and prior to
acceptance of rent for any period thereafter, Landlord may, at its option, and
if permitted pursuant to applicable law, forthwith re-enter and take possession
of the Premises or any part thereof without process or by any legal process in
force in the state where the Property is located. Notwithstanding the
establishment of any holdover tenancy following the expiration or earlier
termination of the Term, if Tenant fails promptly to vacate the Premises at the
expiration or earlier termination of the Term, Tenant shall save Landlord
harmless and indemnified against any claim, loss, cost or expense (including
reasonable attorneys' fees) arising out of Tenant's failure promptly to vacate
the Premises (or any portion thereof) and upon demand pay to Landlord any actual
damages or loss incurred by Landlord as a result of any delayed or terminated
lease of all or part of the Premises by another party.

3.03 RIGHT TO EXTEND.

     3.03(a) EXTENSION TERM. The Term of this Lease of all of the Premises may
be extended for two (2) additional five (5)-year periods (each, an "EXTENSION
TERM") by unconditional written notice from Tenant to Landlord at least 18
months before the end of the then expiring Term, time being of the essence. If
Tenant does not timely exercise this option, or if on the date of such notice,
at the time that Landlord is obligated to provide Tenant with Landlord's
determination of Market Rent as set forth in Section 3.03(b), below, or at the
beginning of the Extension Term (i) a default exists beyond applicable notice
and cure periods or (ii) Tenant has made any Transfer under Article 13 of more
than fifty percent (50%) of the Premises in the aggregate, Tenant's right to
extend shall irrevocably lapse, Tenant shall have no further right to extend,
and this Lease shall expire at the end of the Initial Term.

     All references to the Term shall mean the Initial Term as it may be
extended by the Extension Term. The Extension Term shall be on all the same
terms and conditions except that the Base Rent for the Extension Term shall be
as set forth below.

     3.03(b) EXTENSION TERM BASE RENT. Rent for each year of the applicable
Extension Term shall be established as the higher of (x) one-hundred percent
(100%) of the Market Rent or (y) the Base Rent in effect prior to such Extension
Term and adjusted at the commencement of such Extension Term to reflect the CPI
Adjustment; but Base Rent in an

                                      - 9 -
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Extension Term shall never be less than Base Rent paid prior to such Extension
Term. If Tenant gives Landlord timely notice of its exercise of the Extension
Term option, then Landlord shall give Tenant written notice of Landlord's
determination of Market Rent for the Premises no later than the date that is 16
months before the end of the then-expiring Term. Within ten (10) days after
Tenant receives such notice, Tenant shall notify Landlord of its agreement with
or objection to Landlord's determination of the Market Rent, whereupon in the
case of Tenant's objection, Market Rent shall be determined by arbitration
conducted in the manner set forth below. If Tenant does not notify Landlord
within such ten (10) day period of Tenant's agreement with or objection to
Landlord's determination of the Market Rent, then the Market Rent for the
Extension Term shall be deemed to be Landlord's determination of the Market Rent
as set forth in Landlord's notice to Tenant.

     3.03(c) ARBITRATION OF MARKET RENT. If Tenant timely notifies Landlord of
Tenant's objection to Landlord's determination of Market Rent under the
preceding subsection, such notice shall also set forth a request for arbitration
and Tenant's appointment of a commercial real estate appraiser or broker having
at least ten (10) years experience in the commercial leasing market in the
municipality where the Premises are located (an "ARBITRATOR"). Within five (5)
days thereafter, Landlord shall by notice to Tenant appoint a second Arbitrator.
Each Arbitrator shall determine the Market Rent for the applicable Extension
Term within thirty (30) days after Landlord's appointment of the second
Arbitrator. On or before the expiration of such thirty (30) day period, the two
Arbitrators shall confer to compare their respective determinations of the
Market Rent. If the difference between the amounts so determined by the two
Arbitrators is less than or equal to ten percent (10%) of the lower of said
amounts then the final determination of the Market Rent shall be equal to the
arithmetical average of said amounts. If such difference between said amounts is
greater than ten percent (10%), then the two arbitrators shall within ten (10)
days thereafter to appoint a similarly qualified third Arbitrator ("THIRD
ARBITRATOR"), who shall determine the Market Rent for the applicable Extension
Term within ten (10) days after his or her appointment by selecting one or the
other of the amounts determined by the other two Arbitrators. Each party shall
bear the cost of the Arbitrator selected by such party. The cost for the Third
Arbitrator, if any, shall be shared equally by Landlord and Tenant.

     "MARKET RENT" shall be the fair market rent that willing parties would pay
and receive as the Base Rent to lease the Premises during the Extension Term
under the terms and conditions of this Lease in the condition existing at the
commencement of the Extension Term (or in such better condition as the same are
required to be maintained hereunder). In making such determination, all relevant
factors may be considered, but the Base Rent historically paid under this Lease
shall be disregarded. Market Rent may include annual or periodic increases in
the Base Rent rate if consistent with then prevailing market conditions.

                                     - 10 -
<Page>

     3.03(d) CPI ADJUSTMENT. This Section 3.03(d) shall be used to calculate
increases in Base Rent on account of increases in CPI during the Term of this
Lease. The Consumer Price Index for all Urban Wage Earners and Clerical Workers,
All Items, for Boston, Massachusetts published by the Bureau of Labor Statistics
of the United States Department of Labor (base year 1982-84 = 100) is the "CPI"
If, at the commencement of an Extension Term or as of the commencement of the
second, or any subsequent, Lease Year during the Term of this Lease, there is a
change in the CPI (or any comparable successor or substitute index designated by
the Landlord appropriately adjusted) reflecting an increase in the cost of
living over and above the cost of living as reflected by the CPI for the month
in which the Date of Lease occurs ("BASE PRICE INDEX"), the "CPI ADJUSTMENT" of
the Base Rent shall be calculated as follows: the Base Rent shally be multiplied
by a fraction, the numerator of which shall be the CPI for the month in which
the Extension Term or Lease Year commences, as applicable, and the denominator
of which shall be the Base Price Index. In the event the CPI ceases to use the
1982-84 average of 100 as the basis of calculation, or if a substantial change
is made in the terms or number of items contained in the CPI, then the CPI shall
be adjusted to the figure most nearly approximating that which would have been
arrived at had the manner of computing the CPI in effect at the date of this
Lease not been changed. In the event that within one (1) year following the date
that the CPI figure for any month used in calculating the Adjustment shall have
been published, the federal government shall revise such figure, then: (x) such
revised CPI figure shall thereafter be deemed to be the correct CPI figure for
all purposes (unless the federal government shall yet again revise such figure,
in which case the most recently revised CPI figure shall be deemed to be
correct); and (y) any retroactive adjustment or recomputation resulting from
such revised CPI figure shall be limited to encompass only the year immediately
preceding the date upon which the revision of such CPI figure shall have first
been published.

     3.03(e) RENT CONTINUATION. For any part of the Extension Term during which
the Base Rent is in dispute or has otherwise not finally been determined,
Tenant shall make payment on account of Base Rent at the rate estimated by
Landlord, and the parties shall adjust for any overpayments or underpayments
upon the final determination of Base Rent. The failure by the parties to
complete the process contemplated under this Section prior to commencement of
the Extension Term shall not affect the continuation of the Term or the parties'
obligation to make any adjustments for any overpayments or underpayments for the
Base Rent due for the Extension Term promptly after the determination thereof is
made.

     3.04  EARLY TERMINATION RIGHT. Tenant shall have the one-time right to
terminate the term of this Lease during the Initial Term effective upon the date
(the "EARLY TERMINATION DATE") that is later of (x) the last day of the fifth
Lease Year or (y) the date that is nine months after the delivery by Tenant of
written notice (a "TERMINATION NOTICE") to Landlord electing to terminate the
Lease prior to the then-scheduled expiration date. The Termination Notice must
be accompanied by a check payable to Landlord in an amount equal to one half of
the sum of (A) the unamortized amount (i.e. the amount

                                     - 11 -
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allocable to the remainder of the initial term of the Lease following on and
after the Early Termination Date) of (i) the Finish Work Allowance (as defined
in Exhibit L) and (ii) the brokerage commissions paid by Landlord to the
Brokers, in each case amortized in equal monthly installments that would be
required to fully amortize the amount (without interest) over 120 months and (B)
the product of the then-effective monthly Base Rent times the number of months
remaining in the Initial Term as of the Early Termination Date divided by 15
((A) and (B), together, the "TERMINATION PAYMENT"). An example of the
calculation of the Termination Payment is set forth on EXHIBIT O. In no event
shall the Termination Payment be equal to an amount less than two times the
monthly Base Rent in effect at the time the Termination Notice is given. The
other half of the Termination Payment shall be paid by Tenant to Landlord on or
before the date that is 30 days, prior to the Early Termination Date, net of an
amount equal to 50% of any cash Security Deposit then held by Landlord (provided
that Tenant is not then in default under the lease and that Tenant has not
elected to provide a Letter of Credit as security pursuant to Section 15.01),
and Landlord shall be permitted to apply fifty percent (50%) of any cash
Security Deposit then held by it towards the balance of the Termination Payment.
Within 30 days after request by Tenant, which request shall indicate a projected
Early Termination Date, Landlord shall notify Tenant of the amount of the
Termination Payment that would be payable on such projected date, determined in
accordance with this Section. A request for a determination by Landlord of the
amount of a Termination Payment shall not constitute a Termination Notice. The
Termination Payment shall be in addition to, and not in lieu of, Tenant's
obligations to pay rent for the period ending on the Early Termination Date.
Time is of the essence with regard to the provisions of this Paragraph.

     Tenant's notice terminating the Lease shall be effective only if such
notice is applicable to the entire Premises, is unconditional, is accompanied by
one-half of the Termination Payment, and the remainder of the Termination
Payment is made in a timely manner. Once given, such termination notice shall be
irrevocable. Notwithstanding the foregoing, any exercise by Tenant of its
termination right under this Paragraph shall, at Landlord's election, be void if
Tenant is in default hereunder continuing beyond applicable notice or cure
period or an event or condition exists which with notice and the passage of time
would constitute such a default, provided that, in either case, any such default
is with respect to a payment of Rent or is on account of a breach of the terms
and conditions of Section 9.04 or Section 13.01 of this Lease unless Tenant
cures such default within the applicable cure period, if any, under this Lease
(or unless Tenant otherwise provides Landlord with sufficient assurances, as
determined in Landlord's sole discretion, that Tenant will complete such cure),
either at the time Tenant elects to terminate the Lease or at the time the Lease
would be terminated pursuant to Tenant's election to terminate. If Tenant
exercises its termination right hereunder, (a) Tenant's extension option under
Section 3.03 and rights pursuant to Article 18 shall be null and void, and (b)
Tenant shall peaceably surrender the Premises to Landlord on or before the Early
Termination Date in accordance with the applicable provisions of the Lease.

                                     - 12 -
<Page>

ARTICLE 4: RENT

4.01 BASE RENT. On the Rent Commencement Date and thereafter on the first day of
each month during the Term, Tenant shall pay Landlord the monthly installment of
Base Rent and the monthly installment of Tenant's Pro Rata Share of Total
Operating Costs required by Section 4.02, in each case in advance. Rent shall be
payable at Landlord's address or otherwise as Landlord may designate in writing
from time to time.

4.02 ADDITIONAL RENT.

     4.02(a) GENERAL. "RENT" means Base Rent and Additional Rent. Landlord shall
estimate in advance (i) all Taxes under Article 5, (ii) all utility costs
(unless separately metered to or separately contracted for by Tenant) under
Article 6, (iii) all insurance premiums to be paid by Landlord under Article 7,
and (iv) all Operating Expenses under Section 8.04 (individually all such items
in clauses (i) through (iv) being "OPERATING COSTS" and collectively being
"TOTAL OPERATING COSTS") and Tenant shall pay one-twelfth of Tenant's Pro Rata
Share of such estimated Total Operating Costs monthly in advance together with
Base Rent. Landlord may adjust its estimates of Total Operating Costs at any
time based upon its experience and reasonable anticipation of costs. Such
adjustments shall be effective as of the next Rent payment date after notice to
Tenant. Within one hundred twenty (120) days after the end of each fiscal year
of the Property during the Term, Landlord shall endeavor to give to Tenant a
reasonably detailed statement of the Total Operating Costs paid or incurred by
Landlord during the preceding fiscal year and Tenant's Pro Rata Share of such
expenses. Within the next thirty (30) days, Tenant shall pay Landlord any
underpayment, or Landlord shall credit Tenant with any overpayment, of Tenant's
Pro Rata Share of such Total Operating Costs. If the Term expires or the Lease
is terminated as of a date other than the last day of a fiscal year, Tenant's
payment of Additional Rent pursuant to this Section for such partial fiscal year
shall be based on Landlord's best estimate of the items otherwise includable in
Total Operating Costs and shall be made on or before the later of (a) ten (10)
days after Landlord delivers such estimate to Tenant or (b) the last day of the
Term, with an appropriate payment or refund to be made upon Tenant's receipt of
Landlord's statement of Total Operating Costs for such fiscal year. This Section
shall survive the expiration or earlier termination of the Term.

     At the request of Tenant given within thirty (30) days after Landlord
delivers Landlord's statement of Total Operating Costs, Tenant (at Tenant's
expense) shall have the right to examine Landlord's books and records applicable
to Total Operating Costs for such fiscal year. Such right to examine the records
shall be exercisable: (i) upon reasonable advance notice to Landlord and at
reasonable times during Landlord's business hours; and (ii) only during the
120-day period following Tenant's receipt of statement of Total Operating Costs
for the applicable fiscal year. In the event (i) an audit of Landlord's Total
Operating Costs for such year, conducted by an independent certified public
accountant retained by Tenant or an auditing firm approved by Landlord for such
purpose,

                                     - 13 -
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indicates that certain items were improperly included in Landlord's Total
Operating Costs and resulted in an overcharge to Tenant and (ii) an independent
certified public accountant retained by Landlord at Landlord's expense agrees
with the results of said audit, then Landlord shall refund the overage to
Tenant. Tenant's auditing firm shall be subject to the prior approval of
Landlord, which approval may be granted or denied in Landlord's reasonable
discretion, and shall not be compensated on a contingent fee basis.
Notwithstanding the foregoing, Tenant's request to audit Landlord's books and
records shall not extend the time within which Tenant is obligated to pay the
amounts shown on Landlord's statement of Total Operating Costs, and Tenant may
not make the request to audit Landlord's books and records at any time Tenant is
in default of such payments or otherwise in default beyond applicable notice
and cure periods under the Lease. In the event the audit determines that Tenant
has been overcharged by 10% or more of the Additional Rent due with respect to
Total Operating Costs, Landlord shall pay for the cost of said audit and/or the
arbitration. In all other cases, Tenant shall pay for the cost of said audit
and/or the arbitration.

     As a condition precedent to performing any such examination of Landlord's
books and records, Tenant and its examiners shall be required to execute and
deliver to Landlord an agreement in form acceptable to Landlord agreeing to keep
confidential any information that they discover about Landlord or the Building
or the Property in connection with such examination. Without limiting the
foregoing, such examiners shall also be required to agree that they will not
represent any other tenant in the Building or the Property in connection with
examinations of Landlord's books and records for the Building unless said
tenant(s) have retained said examiners prior to the date of the first
examination of Landlord's books and records conducted by Tenant pursuant to this
Section 8.01 have been continuously represented by such examiners since that
time. Notwithstanding any prior approval of any examiners by Landlord, Landlord
shall have the right to rescind such approval at any time if in Landlord's
reasonable judgment the examiners have breached any confidentiality undertaking
to Landlord or cannot provide acceptable assurances and procedures to maintain
confidentiality.

     This Lease requires Tenant to pay directly to suppliers, vendors, carriers,
contractors, etc., certain insurance premiums, utility costs, personal property
taxes, maintenance and repair costs and other expenses. If Landlord pays any of
these amounts in accordance with this Lease, Tenant shall, upon invoice from
Landlord, reimburse such costs in full with the next monthly Rent payment.
Unless this Lease provides otherwise, Tenant shall pay all Additional Rent then
due on or before the date for the next monthly Rent payment.

     4.02(b) ALLOCATION OF CERTAIN OPERATING COSTS. If at any time during the
Term, Landlord provides services only with respect to particular portions of the
Building or incurs other Operating Costs allocable to particular portions of the
Building, then such Operating Costs shall be charged entirely to those tenants,
including Tenant, if applicable, of such

                                     - 14 -
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portions, notwithstanding the provisions hereof referring to Tenant's Pro Rata
Share. If, during any period for which Landlord's Operating Costs are being
computed, less than all of the Building is occupied by tenants, or if Landlord
is not supplying all tenants with the services being supplied hereunder,
Operating Costs shall be reasonably estimated and extrapolated by Landlord to
determine the Operating Costs that would have been incurred if the Building were
fully occupied for such year and such services were being supplied to all
tenants, and such estimated and extrapolated amount shall be deemed to be the
Operating Costs for such period.

4.03 LATE CHARGE. Tenant acknowledges that if it pays Rent late, Landlord shall
incur unanticipated costs, which shall be extremely difficult to ascertain
exactly. Such costs include processing and accounting charges, and late charges
that may be imposed on Landlord by any mortgage on the Property. Accordingly, if
Landlord does not receive any Rent payment within five (5) days following its
due date, Tenant shall pay Landlord a late charge equal to three (3%) percent of
the overdue amount (provided that no such late charge shall be due with respect
to the first late payment of Rent in any 12 month period unless and until
Landlord gives Tenant notice of such late payment). The parties agree that this
late charge represents a fair and reasonable estimate of the costs Landlord
shall incur by reason of Tenant's payment default. Payment of the late charge
shall not cure Tenant's payment default or prevent Landlord from exercising
other rights and remedies.

4.04 INTEREST. Any late Rent shall bear interest from the date due until paid at
the rate of 12% per annum, except to the extent such interest would cause the
total interest to be in excess of that legally permitted. Payment of interest
shall not cure Tenant's payment default or prevent Landlord from exercising
other rights and remedies.

4.05 METHOD OF PAYMENT. Tenant shall pay the Base Rent to Landlord in advance in
equal monthly installments by the first of each calendar month during the Term.
Tenant shall make a ratable payment of Base Rent and Additional Rent for any
period of less than a month at the beginning or end of the Term. All payments of
Base Rent, Additional Rent and other sums due shall be paid in current U.S.
exchange by check drawn on a clearinghouse bank at the Original Address of
Landlord or such other place as Landlord may from time to time direct, without
demand, set-off or other deduction.

     Without limiting the foregoing, Tenant's obligation so to pay Rent shall be
absolute, unconditional, and independent and shall not be discharged or
otherwise affected by any law or regulation now or hereafter applicable to the
Premises, or any other restriction on Tenant's use, or, except as expressly
provided in herein, any casualty or taking, or any failure by Landlord to
perform or other occurrence; and Tenant assumes the risk of the foregoing and
waives all rights now or hereafter existing to terminate or cancel this Lease or
quit or surrender this Lease or the Premises or any part thereof, or to assert
any defense in the nature of constructive eviction to any action seeking to
recover Rent. Subject to the provisions of this Lease, however, Tenant shall
have the right to seek

                                     - 15 -
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judgments for direct money damages occasioned by Landlord's breach of its Lease
covenants (but may not set-off any such judgment against any Rent or other
amount owing hereunder).

     It is intended that Base Rent payable hereunder shall be a net return to
Landlord throughout the Term, free of expense, charge, offset, diminution or
other deduction whatsoever on account of the Premises (excepting Landlord's
financing expenses, federal and state income taxes of general application, and
those expenses that this Lease expressly makes the responsibility of Landlord),
and all provisions hereof shall be construed in terms of such intent.

4.06 TENANT'S PRO RATA SHARE Tenant's Pro Rata Share is calculated by dividing
the rentable square foot area on the Premises by the rentable square foot area
of the Building, as of the date of the computation. Tenant's Pro Rata Share
initially as set forth in Article 1 is subject to adjustment by Landlord if the
rentable square footages of the Premises or the Building changes. At all times
during the Lease Term, Tenant's Pro Rata Share of Total Operating Costs shall be
calculated as if the Building were 100% occupied at all times during the Lease
Term.

ARTICLE 5: TAXES

5.01 TAXES. Tenant covenants and agrees to pay to Landlord as Additional Rent
Tenant's Pro Rata Share of the Taxes for each fiscal tax period, or ratable
portion thereof, included in the Lease Term. If Landlord receives a refund of
any such Taxes, Landlord shall pay Tenant Tenant's Pro Rata Share of the refund
after deducting Landlord's reasonable costs and expenses incurred in obtaining
the refund (unless such amounts have previously been included in Taxes pursuant
to Section 5.02, below). Tenant shall make estimated payments on account of
Taxes in monthly installments on the first day of each month, in amounts
reasonably estimated from time to time by Landlord pursuant to Section 4.02(a).

5.02 DEFINITION OF "TAXES". "TAXES" means all taxes, assessments, betterments,
excises, user fees and all other governmental charges and fees of any kind or
nature, or impositions or agreed payments in lieu thereof or voluntary payments
made in connection with the provision of governmental services or improvements
of benefit to the Building or the Property (including any so-called linkage,
impact, or voluntary betterment payments), and all penalties and interest
thereon (if due to Tenant's failure to make timely payments), assessed or
imposed against the Premises or the property of which the Premises are a part
(including without limitation any personal property taxes levied on such
property or on fixtures or equipment used in connection therewith), other than a
federal or state income tax of general application. If during the Term the
present system of ad valorem taxation of property shall be changed so that, in
lieu of or in addition to the whole or any part of such ad valorem tax there
shall be assessed, levied or imposed on such property or Premises or

                                     - 16 -
<Page>

on Landlord any kind or nature of federal, state, county, municipal or other
governmental capital levy, income, sales, franchise, excise or similar tax,
assessment, levy, charge or fee (as distinct from the federal and state income
tax in effect on the Date of Lease) measured by or based in whole or in part
upon Building valuation, mortgage valuation, rents, services or any other
incidents, benefits or measures of real property or real property operations,
then any and all of such taxes, assessments, levies, charges and fees shall be
included within the term of Taxes. Taxes shall also include reasonable expenses,
including fees of attorneys, appraisers and other consultants, incurred in
connection with any efforts to obtain abatements or reduction or to assure
maintenance of Taxes for any year wholly or partially included in the Term,
whether or not successful and whether or not such efforts involved filling of
actual abatement applications or initiation of formal proceedings.

5.03 PERSONAL PROPERTY TAXES. Tenant shall pay directly all taxes charged
against Tenant Property (as defined in Section 10.06). Tenant shall use
reasonable efforts to have Tenant Property taxed separately from the Property.
Landlord shall notify Tenant if any of Tenant Property is taxed with the
Property, and Tenant shall pay such taxes to Landlord within fifteen (15) days
of such notice.

ARTICLE 6: UTILITIES

6.01 UTILITY SERVICES. Tenant shall pay all charges for water, sewer, gas, and
electricity ("UTILITY SERVICE") and any other utilities or like services used or
consumed on the Premises, whether called use charge, tax, assessment, fee or
otherwise as the same become due. It is understood and agreed that Landlord
shall be responsible for bringing Utility Service to common switching point(s)
at the Building (collectively, "UTILITY SWITCHING POINTS"). Landlord shall
install, at its sole cost or expense, either separate meters serving the
Premises or sub- or "check" meters for measuring Tenant's consumption of any
Utility Services. Tenant shall pay all costs and expenses associated with any
separately metered utilities (such as telephone) provided exclusively to the
Premises directly to the applicable service provider. Tenant shall pay all costs
and expenses associated with utility charges that are based on a sub-metering or
check metering installation directly to Landlord. With respect to any utilities
that are sub-metered or check metered, Tenant's consumption shall be reasonably
estimated by Landlord. Additional Rent for such utilities may be estimated
monthly by Landlord and shall be paid monthly by Tenant as billed with a final
accounting based upon actual bills following the conclusion of each fiscal year
of the Building. Tenant shall pay for any and all costs to install and connect
Utility Services from the Utility Switching Points to the Premises. Landlord
shall be under no obligation as to any Utility Services beyond the foregoing
responsibility to bring such Utility Services to the Utility Switching Points
and Landlord shall not be liable for any interruption or failure in the supply
of any utilities or Utility Services.

To the extent permitted by law, Landlord shall have the right at any time and
from time to time during the Term to contract for or purchase one or more
Utility Services from

                                     - 17 -
<Page>

any company or third party providing Utility Services (provided that any such
services supplied by an affiliate of Landlord shall be at competitive rates with
other providers) ("UTILITY SERVICE PROVIDER"). Tenant agrees reasonably to
cooperate with Landlord and the Utility Service Providers and at all times as
reasonably necessary, and on reasonable advance notice, shall allow Landlord and
the Utility Service Providers reasonable access to any utility lines, equipment,
feeders, risers, fixtures, wiring and any other such machinery or personal
property within the Premises and associated with the delivery of Utility
Services.

ARTICLE 7: INSURANCE

7.01. COVERAGE. Tenant shall maintain during the Term insurance for the benefit
of Tenant and Landlord (as their interests may appear) from insurers rated at
least A-/X by A. M. Best, with terms and coverages reasonably satisfactory to
Landlord, and with such increases in limits from time to time as may be required
by institutional real estate lenders in similar buildings in Cambridge,
Massachusetts. Initially, Tenant shall maintain the following on an occurrence
basis:

     (i) Commercial general liability insurance, using an ISO Occurrence Form,
naming Landlord, Landlord's management, leasing and development agents and
Landlord's mortgagee(s) from time to time as additional insureds, with coverage
for premises/operations, personal injury, products/completed operations,
independent contractors, and contractual liability with combined single limits
of liability of not less than $3,000,000 for bodily injury and property damage
per occurrence. Limits can be achieved by an underlying General Liability policy
and an Umbrella Liability policy, provided the terms of the Umbrella policy are
at least as broad as the underlying policy.

     (ii) Property insurance covering property damage and business income/extra
expense. Covered property shall include all tenant improvements in the Premises
(including any Finish Work or other Tenant Work), and all other items of Tenant
Property. Such insurance, with respect only to tenant improvements, shall name
Landlord and Landlord's mortgagees from time to time as additional loss payees
as their interests may appear. Such insurance shall be written on a special
perils of physical loss or damage basis including but not limited to the perils
of fire, extended coverage, windstorm, vandalism, malicious mischief, sprinkler
leakage, flood, earth movement, and including comprehensive boiler and machinery
(equipment breakdown) for the full replacement cost value of the covered items
with coinsurance waived by the inclusion of Agreed Amount, with a deductible not
to exceed $10,000. Tenant shall maintain Business Income/Extra Expense at limits
sufficient to cover the costs of operations for not less than six (6) months.

     (iii) Workers' compensation insurance with statutory benefits and
employers' liability insurance in the following amounts: each accident,
$500,000; disease (policy limit), $500,000; disease (each employee), $500,000.

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     Prior to the Term Commencement Date and on each anniversary of that date
(or on the policy renewal date), Tenant shall give Landlord certificate(s)
evidencing such coverage and stating that it may not be changed or canceled
without at least thirty (30) days' prior written notice to Landlord and Tenant.
Insurance maintained by Tenant shall be deemed to be primary insurance, and any
insurance maintained by Landlord shall be deemed secondary to it.

7.02 AVOID ACTION INCREASING RATES. Tenant shall comply with Sections 9.01,
9.02, 9.03, and 9.04 and in addition shall not, directly or indirectly, use the
Premises in any way that is prohibited by law or dangerous to people or property
or which may jeopardize or increase the cost of any insurance coverage or
require additional insurance. Tenant shall cure any breach of this Section
within ten (10) days after notice from Landlord by (i) stopping any use that
jeopardizes any insurance coverage or increases its cost and (ii) paying the
increased cost of insurance (provided that Landlord shall cooperate with Tenant,
at no out-of-pocket cost to Landlord, to attempt to eliminate any such increased
cost if Tenant stops such use promptly after notice from Landlord). Tenant shall
have no further notice or cure right under Article 14 for any such breach.
Tenant shall reimburse Landlord for all of Landlord's costs incurred in
providing any insurance that is attributable to any special endorsement or
increase in premium resulting from the business or operations of Tenant, and any
special or extraordinary risks or hazards resulting therefrom, including without
limitation, any risks or hazards associated with the generation, storage and
disposal of medical waste.

7.03 WAIVER OF SUBROGATION. Landlord and Tenant each waive any and every claim
for recovery from the other for any and all loss of or damage to the Property or
any part of it, or to any of its contents, which loss or damage is covered by
valid and collectible property insurance. Landlord waives any and every such
claim against Tenant that would have been covered had the insurance policies
required to be maintained by Landlord by this Lease been in force, to the
extent that such loss or damage would have been recoverable under such
policies. Tenant waives any and every such claim against Landlord that would
have been covered had the insurance policies required to be maintained by Tenant
under this Lease been in force, to the extent that such loss or damage would
have been recoverable under such policies. This mutual waiver precludes the
assignment of any such claim by subrogation (or otherwise) to an insurance
company (or any other person), and Landlord and Tenant each agree to give
written notice of this waiver to each insurance company that has issued or shall
issue any property insurance policy to it, and to have the policy properly
endorsed, if necessary, to prevent invalidation of the insurance coverage
because of this waiver.

7.04 LANDLORD'S INSURANCE. Landlord shall purchase and maintain during the Term
with insurance companies qualified to do business in the state where the
Property is located insurance that may include the following: (i) commercial
general liability insurance for

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incidents occurring in the common areas, with coverage for premises/operations,
personal and advertising injury, products/completed operations and contractual
liability with combined single limits of liability of not less than $5,000,000
for bodily injury and property damage per occurrence, together with such other
coverages and risks as Landlord shall reasonably decide or a mortgagee may
require; and (ii) property insurance covering property damage to the Building,
excluding any Tenant Work, and loss of rental income, on an "all risk" of
physical loss or damage basis, for full replacement cost value of the Building,
with co-insurance waived by inclusion of an agreed amount endorsement together
with such other coverages and risks as Landlord shall reasonably decide or a
mortgagee or a ground lessor may require. As set forth in Section 4.02, the cost
thereof shall be borne by Tenant and other tenants. Landlord may use blanket or
excess umbrella coverage to satisfy any of the requirements in this Section
7.04. As set forth in Section 4.02, the cost thereof shall be borne by Tenant
and other tenants.

ARTICLE 8: COMMON EXPENSES

8.01 OPERATING EXPENSES. "OPERATING EXPENSES" shall mean all costs and expenses
associated with the ownership, operation, maintenance and repair of the Property
and of all heating, ventilating, air conditioning, plumbing, electrical, utility
and safety systems for the Building. Operating Expenses include without
limitation the costs and expenses incurred in connection with the following:
compliance with Landlord's obligations under Section 10.03(b); planting and
landscaping; snow removal; utility, water and sewage services; maintenance of
signs; supplies, materials and equipment purchased or rented, total wage and
salary costs paid to, and all contract payments made on account of, all persons
to the extent engaged in the operation, maintenance, security, cleaning and
repair of the Property, including Social Security, old age and unemployment
taxes and so-called "fringe benefits"; services generally furnished to all
tenants of the Property; maintenance, repair and replacement of Building
equipment and components; utilities consumed and expenses incurred in the
operation, maintenance and repair of the Property; costs incurred by Landlord to
comply with the terms and conditions of any changes in the governmental
approvals affecting operations of the Property existing as of the date of this
Lease; workers' compensation insurance and property, liability and other
insurance premiums; personal property taxes; rental or lease payments paid by
Landlord for rented or leased personal property used in the operation or
maintenance of the Property; fees for required licenses and permits; maintenance
and repair of the parking garage and paving (including sweeping, striping,
repairing, resurfacing, and repaving); refuse removal; security; and property
management fees, which fees shall not exceed a commercially reasonable amount
or, if such management is provided by an affiliate of Landlord, three percent
(3%) of gross income from the Property. Landlord may use third parties or
affiliates to perform any of these services, and the cost thereof shall be
included in Operating Expenses. Costs referred to in this Section shall be
ascertained in accordance with generally accepted accounting principles, and
allocated to appropriate fiscal periods on the accrual method of accounting.
Specifically, any capital expenditures for installation of capital items shall
be amortized

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(with interest at Landlord's cost of funds) over the useful life of the capital
item installed. Landlord shall make a reasonable allocation of the cost of any
Operating Expenses incurred jointly for the Property and any other property.

     Operating Expenses shall not include: the cost of performing Landlord's
obligations under Section 10.03(a); the cost of casualty repairs to the extent
covered by insurance, (except for reasonable deductibles paid by Landlord under
insurance policies maintained by Landlord); costs associated with the operation
of the business of Landlord and/or the sale and/or financing of the Property, as
distinguished from the cost of Property operations, maintenance and repair; and
costs of disputes between Landlord and its employees, tenants or contractors. In
addition, Operating Expenses shall not include the cost of Base Building Work,
including the Tenant Related Work; capital expenditures for additional
improvements at the Property that result in a material increase in the rentable
square footage of the Property; interest or principal payments on any mortgage
encumbering the Property; depreciation of the Property; advertising, legal and
space planning expenses and leasing commissions and other costs and expenses
incurred in leasing space to tenants for the Property; legal and other expenses
incurred in the negotiation or enforcement of leases; work done for specific
tenants of the Property, not for all tenants of the Property in general; the
cost of utilities outside normal business hours sold to specific tenants of the
Property; costs incurred in the sale or refinancing of the Property; and any
expenses otherwise includable within Operating Expenses to the extent actually
reimbursed by persons other than tenants under leases for space in the Property.

     Tenant shall pay Tenant's Pro Rata Share of Operating Expenses in
accordance with Section 4.02.

ARTICLE 9: USE OF PREMISES

9.01 PERMITTED USES. Tenant may use the Premises only for the Permitted Uses
described in Article 1. Tenant shall keep the Premises equipped with appropriate
safety appliances to the extent required by applicable laws or insurance
requirements.

9.02 INDEMNIFICATION. Tenant shall assume exclusive control of all areas of the
Premises, including all improvements, utilities, equipment, and facilities
therein. Tenant is responsible for the Premises and any Tenant's improvements,
equipment, facilities and installations, wherever located on the Property and
all liabilities, including without limitation tort liabilities, incident
thereto. Tenant shall indemnify, save harmless and defend Landlord and
Landlord's members, managers, officers, mortgagees, agents, employees,
independent contractors, invitees and other persons acting under them
(collectively, "INDEMNITEES") from and against all liability, claim or cost
(including reasonable attorneys' fees) arising in whole or in part out of (i)
any injury, loss, theft or damage (except to the extent due to the gross
negligence or willful misconduct of Landlord or its employees) to any person or
property while on or about the Premises or the Property;

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(ii) any condition within the Premises or, to the extent caused by Tenant, the
Property; (iii) failure to comply with any Lease covenant by Tenant; (iv) the
use of the Premises or the Property by, or any act or omission of, Tenant or
persons claiming by, through or under Tenant, or any of its agents, employees,
independent contractors, suppliers or invitees; or (v) any labor disharmony with
workers employed by Landlord to undertake the Base Building Work or other work
at the Property undertaken by Landlord, from time to time, caused by Tenant or
any Tenant Contractor, including without limitation coordination difficulties,
or delays to or impairing of any guaranties, warranties or the work of any other
contractor, in each use paying any cost to Landlord on demand as Additional
Rent. The provisions of this Section shall survive the expiration or earlier
termination of this Lease.

9.03 COMPLIANCE WITH LEGAL REQUIREMENTS. Tenant shall not cause or permit the
Premises or the Property to be used in any way that violates any law, code,
ordinance, restrictive covenant, encumbrance, governmental regulation, order,
permit, approval or any provision of the Lease (each a "LEGAL REQUIREMENT"),
annoys or interferes with the rights of tenants of the Property, or constitutes
a nuisance or waste. Tenant shall obtain and pay for all permits and shall
promptly take all actions necessary to comply with all Legal Requirements,
including without limitation the Occupational Safety and Health Act, applicable
to Tenant's use of the Premises. Tenant shall maintain in full force and effect
all certifications or permissions to provide its services required by any
authority having jurisdiction to authorize, franchise or regulate such services.
Tenant shall be solely responsible for procuring and complying at all times with
any and all necessary permits directly relating or incident to: the conduct of
its activities on the Premises; its scientific experimentation, transportation,
storage, handling, use and disposal of any chemical or radioactive or
bacteriological or pathological substances or organisms or other hazardous
wastes or environmentally dangerous substances or materials or medical waste.
Within ten (10) days of a request by Landlord, which request shall be made not
more than once during each period of twelve (12) consecutive months during the
Term hereof, unless otherwise requested by any mortgagee of Landlord, Tenant
shall furnish Landlord with copies of all such permits that Tenant possesses or
has obtained together with a certificate certifying that such permits are all of
the permits that Tenant possesses or has obtained with respect to the Premises.
Tenant shall promptly give notice to Landlord of any warnings or violations
relative to the above received from any federal, state, or municipal agency or
by any court of law and shall promptly cure the conditions causing any such
violations. Tenant shall not be deemed to be in default of its obligations under
the preceding sentence to promptly cure any condition causing any such violation
in the event that, in lieu of such cure, Tenant shall contest the validity of
such violation by appellate or other proceedings permitted under applicable law,
provided that: (i) any such contest is made reasonably and in good faith, (ii)
Tenant makes provisions, including, without limitation, posting bond(s) or
giving other security, acceptable to Landlord to protect Landlord, the Building
and the Property from any liability, costs, damages or expenses arising in
connection with such violation and failure to cure, (iii) Tenant shall agree to
indemnify, defend (with counsel reasonably acceptable to Landlord) and hold
Landlord harmless from and against any and all liability,

                                     - 22 -
<Page>

costs, damages, or expenses arising in connection with such condition and/or
violation, (iv) Tenant shall promptly cure any violation in the event that its
appeal of such violation is overruled or rejected, and (v) Tenant shall certify
to Landlord's satisfaction that Tenant's decision to delay such cure shall not
result in any actual or threatened bodily injury or property damage to Landlord,
any tenant or occupant of the Building or the Property, or any other person or
entity. Landlord covenants that, upon completion of the Base Building Work, the
common areas of the Building shall comply with the provisions of the Americans
with Disabilities Act of 1990, 42 U.S.C. Section 12101 ET SEQ., as then in
effect.

9.04 ENVIRONMENTAL SUBSTANCES. "ENVIRONMENTAL LAW" means all statutes, laws,
rules, regulations, codes, ordinances, standards, guidelines, authorizations and
orders of federal, state and local public authorities pertaining to any of the
Environmental Substances or to environmental compliance, contamination, cleanup
or disclosures of any release or threat of release to the environment, of any
hazardous, biological, chemical, radioactive or toxic substances, wastes or
materials, any pollutants or contaminants which are included under or regulated
by any municipal, county, state or federal statutes, laws, rules, regulations,
codes, ordinances, standards, guidelines, authorizations or orders, including,
without limitation, the Toxic Substances Control Act, 15 U.S.C. Section 2601, ET
SEQ.; the Clean Water Act, 33 U.S.C. Section 1251, ET SEQ.; the Clean Air Act,
42 U.S.C. Section 7401, ET SEQ.; the Safe Drinking Water Act, 42 U.S.C. Section
300f-300j, ET SEQ.; the Federal Water Pollution Control Act, 33 U.S.C. Section
1321, ET SEQ.; the Solid Waste Disposal Act, 42 U.S.C Section 6901, ET SEQ.; the
Comprehensive Environmental Response, Compensation and Liability Act of 1980, 42
U.S.C. Section 9601 ET SEQ.; the Federal Resource Conservation and Recovery
Act, 42 U.S.C. Section 6901 ET SEQ.; the Superfund Amendments and
Reauthorization Act of 1986, Public Law No. 99-499 (signed into law October 17,
1986); M.G.L. c.21C; and oil and hazardous materials as defined in M.G.L. c.21E,
as any of the same are from time to time amended, and the rules and regulations
promulgated thereunder, and any judicial or administrative interpretation
thereof, including any judicial or administrative orders or judgments, and all
other federal, state and local statutes, laws, rules, regulations, codes,
ordinances, standards, guidelines, authorizations and orders regulating the
generation, storage, containment or disposal of any Environmental Substances,
including but not limited to those relating to lead paint, radon gas, asbestos,
storage and disposal of oil, biological, chemical, radioactive and hazardous
wastes, substances and materials, and underground and above ground oil storage
tanks; and any amendments, modifications or supplements of any of the foregoing.

     "ENVIRONMENTAL SUBSTANCES" means, but shall not be limited to, any
hazardous substances, hazardous waste, environmental, biological, chemical,
radioactive substances, oil or petroleum products and any waste or substance,
which because of its quantitative concentration, chemical, biological,
radioactive, flammable, explosive, infectious or other characteristics,
constitutes or may reasonably be expected to constitute or contribute to a
danger or hazard to public health, safety or welfare or to the environment,
including without limitation any asbestos (whether or not friable) and any
asbestos-containing

                                     - 23 -
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materials, lead paint, waste oils, solvents and chlorinated oils,
polychlorinated biphenyls (PCBs), toxic metals, etchants, pickling and plating
wastes, explosives, reactive metals and compounds, pesticides, herbicides, radon
gas, urea formaldehyde foam insulation and chemical, biological and radioactive
wastes, or any other similar materials that are mentioned under or regulated by
any Environmental Law; and the regulations adopted under these acts, and
including any other products or materials subsequently found by an authority of
competent jurisdiction to have adverse effects on the environment or the health
and safety of persons.

     Tenant shall neither cause or permit any Environmental Substances to be
generated, produced, brought upon, used, stored, treated or disposed of in or
about or on the Building by Tenant, nor permit or suffer persons acting under
Tenant, to do the same, whether with or without negligence, without (i)
Landlord's prior written consent and (ii) complying with all applicable
Environmental Laws and Legal Requirements pertaining to the transportation,
storage, use or disposal of such Environmental Substances, including obtaining
proper permits. Landlord may take into account any factors or facts that
Landlord reasonably believes relevant in determining whether to grant its
consent. Landlord consents to Tenant's use of the Environmental Substances
listed in EXHIBIT F. From time to time at Landlord's request, Tenant shall
execute affidavits, representations and the like concerning Tenant's best
knowledge and belief regarding the presence or absence of Environmental
Substances on the Premises or the Property. Tenant agrees to pay the cost of any
environmental inspection or assessment requested by any lender that holds a
security interest in the Property or this Lease, or by any insurance carrier, to
the extent that such inspection or assessment pertains to any release,
contamination, loss or damage or determination of condition in the Premises.

     If any transportation, storage, use or disposal of Environmental Substances
on or about the Property by Tenant, its agents, employees, independent
contractors, or invitees results in any escaped, or release, threat of release,
contamination of the soil or surface or ground water or any loss or damage to
person or property, Tenant agrees to: (a) notify Landlord immediately of the
occurrence; (b) after consultation with Landlord, clean up the occurrence in
full compliance with all applicable statutes, regulations and standards and (c)
indemnify, defend and hold Landlord, and the Indemnitees harmless from and
against any claims, suits, causes of action, costs and fees, including
attorneys' fees and costs, arising from or connected with any such occurrence.
In the event of such occurrence, Tenant agrees to cooperate fully with Landlord
and provide such documents, affidavits, information and actions as may be
requested by Landlord (1) to comply with any Environmental Law or Legal
Requirement, (2) to comply with any request of any mortgagee or tenant, and/or
(3) for any other reason deemed necessary by Landlord in its sole discretion. In
the event of any such occurrence that is required to be reported to a
governmental authority under any Environmental Law or Legal Requirement, Tenant
shall simultaneously deliver to Landlord copies of any notices given or received
by Tenant and

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shall promptly pay when due any fine or assessment against Landlord, Tenant, or
the Premises or Property relating to such occurrence.

     The provisions of this Section shall survive the expiration or earlier
termination of this Lease.

9.05 SIGNS AND AUCTIONS. Except as provided in this Section, no sign, antenna or
other structure or thing, shall be erected or placed on the Premises or any part
of the exterior of the Building or erected so as to be visible from the exterior
of the Building, without first securing the written consent of the Landlord.
Landlord, at Landlord's cost, shall provide building standard lobby and floor
signage identifying Tenant and, at Tenant's request, any subtenants permitted
pursuant to Section 13, provided that Tenant reimburses Landlord upon demand for
Landlord's cost to modify such lobby and floor signage. Any signage requested by
Tenant at Tenant's entry shall be the responsibility of Tenant and subject to
Landlord's prior written approval. Tenant shall not conduct or permit any
auctions or sheriff's sales at the Property.

     Notwithstanding the foregoing to the contrary, so long as Tenant occupies
and conducts its business in at least 75 percent of the Premises, Tenant, at its
sole cost and expense (including without limitation all costs in obtaining any
and all required permits and governmental approvals) may install such other
signage identifying Tenant on the exterior of the Building as may be allowed
pursuant to Legal Requirements, provided that (i) Tenant obtains Landlord's
prior written consent (which shall not be unreasonably withheld, conditioned or
delayed) to the location and design of such signs and (ii) the square footage of
any such signs, in the aggregate, does not exceed Tenant's Pro Rata Share of the
aggregate square footage available to all tenants for such signs pursuant to
Legal Requirements minus any square footage reserved by Landlord for
multi-tenant signs. Tenant's rights under the preceding sentence are
non-transferable. Any transfer of Tenant's signage rights shall automatically
render such signage rights immediately null and void. Tenant shall repair and
maintain any signs installed by it pursuant to the preceding sentence at its
sole cost and expense and shall install such signs in compliance with the
provisions of Section 10.05 of this Lease.

9.06 LANDLORD'S ACCESS. Landlord or its agents may enter the Premises at all
reasonable times to show the Premises to potential buyers, lenders, or investors
and, within the last 18 months of the Term or any extended term, to prospective
tenants; to inspect and conduct tests in order to monitor Tenant's compliance
with Legal Requirements governing Environmental Substances; for purposes
described in Sections 2.01, 9.04 and/or 10.04(b) or for any other purpose
Landlord reasonably deems necessary. Landlord shall give Tenant a minimum of 24
hours prior notice (which may be oral) of such entry and shall not enter
Tenant's technical areas (if Tenant has previously notified Landlord in writing
of the location and extent of such technical areas) unless accompanied by
Tenant's representative (whom Tenant shall promptly provide). However, in case
of emergency, Landlord may

                                     - 25 -
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enter any part of the Premises without prior notice or Tenant's representative
and shall make reasonable efforts to notify Tenant.

ARTICLE 10: CONDITION AND MAINTENANCE OF PREMISES AND PROPERTY

10.01 EXISTING CONDITIONS. Except as expressly set forth herein with respect to
the Tenant Related Work, Tenant shall accept the Premises and Property in their
condition as of the Delivery Date to Tenant "as is" and subject to all recorded
matters and Legal Requirements. Tenant acknowledges that except for any express
representations in this Lease, neither Landlord nor any person acting under
Landlord has made any representation as to the condition of the Property or the
suitability of the Property for Tenant's intended use. Tenant represents and
warrants that Tenant has made its own inspection and inquiry regarding the
Property and is not relying on any representations of Landlord or any Broker or
persons acting under either of them.

10.02 EXEMPTION AND LIMITATION OF LANDLORD'S LIABILITY.

     10.02(a) EXEMPTION OF LANDLORD FROM LIABILITY. Tenant shall insure its
personal property under an all risk full replacement cost property insurance
policy. Landlord shall not be liable for any damage or injury to the person,
property or business (including loss of revenue, profits or data) of Tenant,
Tenant's employees, agents, contractors, or invitees, or any other person on or
about the Property; provided, however, that this Section 10.02(a) shall not
exempt Landlord from liability for Landlord's negligence or willful misconduct
solely to the extent that such liability cannot be waived by Landlord pursuant
to applicable law. This exemption shall apply whether such damage or injury is
caused by (among other things): (i) fire, steam, electricity, water, gas,
sewage, sewer gas or odors, snow, ice, frost or rain; (ii) the breakage,
leakage, obstruction or other defects of pipes, faucets, sprinklers, wires,
appliances, plumbing, windows, air conditioning or lighting fixtures or any
other cause; (iii) any other casualty or any Taking; (iv) theft; (v) conditions
in or about Property or from other sources or places; or (vi) any act or
omission of any other tenant.

     10.02(b) LIMITATION ON LANDLORD'S LIABILITY. Tenant agrees that Landlord
shall be liable only for breaches of its covenants occurring while it is owner
of the Property (provided, however, that if Landlord from time to time is lessee
of the ground or improvements constituting the Building, then Landlord's period
of ownership of the Property shall be deemed to mean only that period while
Landlord holds such leasehold interest). Upon any sale or transfer of the
Building, the transferor Landlord (including any mortgagee) shall be freed of
any liability or obligation thereafter arising and Tenant shall look solely to
the transferee Landlord as aforesaid for satisfaction of such liability or
obligation. Tenant and each person acting under Tenant agrees to look solely to
Landlord's interest from time to time in the Property for satisfaction of any
claim against Landlord. No owner, trustee, beneficiary, partner, member,
manager, agent, or employee of Landlord

                                     - 26 -
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(or of any mortgagee or any lender or ground or improvements lessor) nor any
person acting under any of them shall ever be personally or individually liable
to Tenant or any person claiming under or through Tenant for or on account of
any default by Landlord or failure by Landlord to perform any of its obligations
hereunder, or for or on account of any amount or obligations that may be or
become due under or in connection with this Lease or the Premises; nor shall it
or they ever be answerable or liable in any equitable judicial proceeding or
order beyond the extent of their interest in the Property. No deficit capital
account of any member or partner of Landlord shall be deemed to be a liability
of such member or partner or an asset of Landlord. Any lien obtained to enforce
any judgment against Landlord shall be subject and subordinate to any mortgage
encumbering the Property. In no event shall Landlord (or any such persons) ever
be liable to Tenant for indirect or consequential damages.

10.03 LANDLORD'S OBLIGATIONS.

     10.03(a) BASE BUILDING WORK. Landlord shall complete certain renovations to
the Building in substantial accordance with the plans and specifications
described in EXHIBIT I, with such changes as Landlord may determine in its
discretion ("BASE BUILDING WORK"), provided such changes, if made following the
approval of the Construction Documents for the Finish Work, do not have any
material adverse affect on Tenant's ability to complete the Finish Work. The
Base Building Work shall be done at Landlord's sole cost and expense. Tenant
acknowledges that portions of the Base Building Work may be done before,
simultaneously with, and/or after Finish Work, as hereinafter defined. The Base
Building Work includes certain work necessary for the demising of the Premises
as further described on EXHIBIT J, attached (the "TENANT RELATED WORK").

     10.03(b) REPAIR AND MAINTENANCE. Subject to the provisions of Article 12,
and except for damage caused by any act or omission of Tenant or persons acting
under Tenant, Landlord shall keep the Building and the foundation, roof,
Building systems (to the extent not serving the Premises exclusively),
structural supports, exterior windows and exterior walls of the Building in good
order, condition and repair, reasonable wear and tear excepted. Landlord shall
not be obligated to maintain or repair any interior windows, doors, plate glass,
the surfaces of walls or other fixtures, components or equipment within the
Premises, but the same shall be Tenant's obligation. Tenant shall promptly
report in writing to Landlord any defective condition known to it that Landlord
is required to repair. Tenant waives the benefit of any present or future law
that provides Tenant the right to repair the Premises or Property at Landlord's
expense or to terminate this Lease because of the condition of the Property or
Premises to the extent such benefit of law may be waived by Tenant.

10.04 TENANT'S OBLIGATIONS.

                                     - 27 -
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     10.04(a) REPAIR AND MAINTENANCE. Except for work that Section 10.03 or
Article 12 requires Landlord to do, Tenant at its sole cost and expense shall
keep the Premises including without limitation all fixtures, systems and
equipment now or hereafter on the Premises, or elsewhere exclusively serving the
Premises, in good order, condition and repair (and at least as good order,
condition and repair as they are in on the Commencement Date or may be put in
during the Term), reasonable wear and tear excepted; shall keep in a safe,
secure and sanitary condition all trash and rubbish temporarily stored at the
Premises; and shall make all repairs and replacements and to do all other work
necessary for the foregoing purposes whether the same may be ordinary or
extraordinary, foreseen or unforeseen. The foregoing shall include without
limitation Tenant's obligation to maintain floors and floor coverings, to paint
and repair walls and doors, to replace and repair all interior glass and
windows, ceiling tiles, lights and light fixtures, pipes, drains and the like in
the Premises. Without limitation, Tenant shall be responsible for heating,
ventilating and air-conditioning systems and Utility Services serving the
Premises from the point where such systems serve the Premises exclusively
(including the Utility Switching Points to the Premises), and Tenant shall
secure, pay for, and keep in force contracts with appropriate and reputable
service companies reasonably approved by Landlord providing for the regular
maintenance of such heating, ventilating and air-conditioning and Utility
Services systems serving the Premises to the extent that such systems do not
serve other tenants of the Property. If anything required pursuant to Section
10.04(a) to be repaired cannot be fully repaired or restored, Tenant shall
replace it at Tenant's cost, even if the benefit or useful life of such
replacement extends beyond the Term. Tenant shall hire its own cleaning
contractor for the Premises.

     10.04(b) LANDLORD'S RIGHT TO CURE. If Tenant does not perform any of its
obligations under Section 10.04(a), Landlord upon ten (10) days' prior notice to
Tenant (or without prior notice in the case of an emergency) may perform such
maintenance, repair or replacement on Tenant's behalf, and Tenant shall
reimburse Landlord for all costs reasonably incurred, together with an
Administrative Charge, which payment shall be made, after written demand by
Landlord, with the next payment of Rent hereunder.

     10.04(c) FINISH WORK. Tenant shall perform all work, other than Base
Building Work, required to prepare the Premises for Tenant's use and occupancy
(the "FINISH WORK"). Any Finish Work constructed by Tenant shall be performed in
accordance with, and subject to, the provisions of Section 10.05 and the Finish
Work Letter attached as EXHIBIT L of the Lease. Tenant must expend at least
$45.00 per square foot of the Premises for the Finish Work, which shall be of
the type of work suitable for a first class office, laboratory, and research and
development facility, and the Finish Work must be completed by Tenant on or
before the date that is two (2) months after the Delivery Date.

10.05 TENANT WORK.

                                     - 28 -
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     10.05(a) GENERAL. "TENANT WORK" shall mean all work, including Finish Work,
demolition, improvements, additions and alterations, in or to the Premises but
excluding Base Building Work. Without limitation, Tenant Work includes any
penetrations in the walls, partitions, ceilings or floors and all attached
carpeting, all signs visible from the exterior of the Premises, and any change
in the exterior appearance of the windows in the Premises (including shades,
curtains and the like). All Tenant Work shall be subject to Landlord's prior
written approval and shall be arranged and paid for by Tenant all as provided
herein; provided that any interior, non-structural Tenant Work (including any
series of related Tenant Work projects) that (a) costs less than the Tenant Work
Threshold Amount (which shall be $50,000), (b) does not interconnect with or
materially affect any fire-safety, telecommunications, electrical, mechanical,
ventilation or plumbing systems of the Building ("CORE BUILDING SYSTEMS"), and
(c) does not affect any penetrations in or otherwise affect any walls, floors,
roofs, or other structural elements of the Building or any signs visible from
the exterior of the Premises or any change in the exterior appearance of the
windows in the Premises (including shades, curtains and the like) shall not
require Landlord's prior approval if Tenant delivers the Construction Documents
(as defined in Section 10.05(b)) (or, if such work is of the type for which
Construction Documents are not typically prepared in a first class office and
laboratory building, such other description as is reasonably satisfactory to
Landlord) for such work to Landlord at least five (5) business days' prior to
commencing such work. Whether or not Landlord's approval is required, Tenant
shall neither propose nor effect any Tenant Work that in Landlord's reasonable
judgment (i) adversely affects any structural component of the Building, (ii)
would be incompatible with the Core Building Systems, (iii) affects the exterior
or the exterior appearance of the Building or common areas within or around the
Building or other property than the Premises, (iv) diminishes the value of the
Premises, or (v) requires any unusual expense to readapt the Premises. Prior to
commencing any Tenant Work affecting air disbursement from ventilation systems
serving Tenant or the Building, including without limitation the installation of
Tenant's exhaust systems, Tenant shall provide Landlord with a third party
report from a consultant, and in a form reasonably acceptable to Landlord,
showing that such work will not adversely affect the ventilation systems or air
quality of the Building (or of any other tenant in the Building) and shall, upon
completion of such work, provide Landlord with a certification reasonably
satisfactory to Landlord from such consultant confirming that no such adverse
effects have resulted from such work.

     10.05(b) CONSTRUCTION DOCUMENTS. No Tenant Work shall be effected except in
accordance with complete, coordinated construction drawings and specifications
("CONSTRUCTION DOCUMENTS") prepared in accordance with EXHIBIT G. Prior to the
commencement of any Tenant Work requiring Landlord's approval hereunder, Tenant
shall obtain Landlord's prior written approval of the Construction Documents for
such work, which approval shall not be unreasonably withheld. The Construction
Documents shall be prepared by an architect ("TENANT'S ARCHITECT") registered in
the Commonwealth of Massachusetts and experienced in the construction of tenant
space improvements in

                                     - 29 -
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comparable buildings in the area where the Premises are located and, if the
value of such Tenant Work will equal or exceed the Tenant Work Threshold Amount
or will affect any Core Building Systems or structural components of the
Building, the identity of Tenant's Architect shall be approved by Landlord in
advance, such approval not to be unreasonably withheld in the case of interior,
non-structural alterations. Tenant shall be solely responsible for the
liabilities associated with and expenses of all architectural and engineering
services relating to Tenant Work and for the adequacy, accuracy, and
completeness of the Construction Documents even if approved by the Landlord (and
even if Tenant's Architect has been otherwise engaged by Landlord in connection
with the Base Building Work). The Construction Documents shall set forth in
detail the requirements for construction of the Tenant Work and shall show all
work necessary to complete the Tenant Work including all cutting, fitting, and
patching and all connections to the mechanical, electrical, and plumbing systems
and components of the Building. Submission of the Construction Documents to
Landlord for approval shall be accompanied by a certification of Tenant's
Architect that all Tenant Work described in the Construction Documents (i)
complies with all applicable laws, regulations, building codes, and first class
design standards, (ii) does not adversely affect any structural component of the
Building, (iii) is compatible with and does not adversely affect the Core
Building Systems, (iv) does not affect any property other than the Premises, (v)
conforms to floor loading limits specified by Landlord and its consultants, and
(vi) and with respect to all materials, equipment and special designs, processes
or products, does not infringe on any patent or other proprietary rights of
others. The Construction Documents shall comply with Landlord's requirements for
the uniform exterior appearance of the Building, including without limitation
the use of Building standard window blinds and Building standard light fixtures
within fifteen (15) feet of each exterior window. Landlord's approval of
Construction Documents shall signify only Landlord's consent to the Tenant Work
shown and shall not result in any responsibility of Landlord concerning
compliance of the Tenant Work with laws, regulations, or codes, or coordination
or compatibility with any component or system of the Property, or the
feasibility of constructing the Tenant Work without damage or harm to the
Building, all of which shall be the sole responsibility of Tenant.

     10.05(c) PERFORMANCE. The identity of any person or entity (including any
employee or agent of Tenant) performing or designing any Tenant Work ("TENANT
CONTRACTOR") shall, if the cost of such work in any instance is in excess of the
Tenant Work Threshold Amount or will affect any Core Building Systems or
structural components of the Building or involves any work other than interior,
nonstructural alterations, be approved in advance by Landlord. Landlord hereby
approves Suffolk Construction Company as a potential Tenant Contractor for the
Finish Work and, provided that Tenant can provide evidence satisfactory to the
Landlord that The Richmond Group will not cause Tenant to breach the covenants
set forth in this Lease regarding labor harmony, Landlord shall approve The
Richmond Group as a potential Tenant Contractor for the Finish Work. Once any
Tenant Contractor has been approved, then the same Tenant Contractor may
thereafter be used by Tenant for the same type of work until Landlord notifies
Tenant that such Tenant Contractor is no longer

                                     - 30 -
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approved. Tenant shall procure at Tenant's expense all necessary permits and
licenses before undertaking any Tenant Work. Tenant shall perform all Tenant
Work at Tenant's risk in compliance with all applicable laws and in a good and
workmanlike manner employing new materials of good quality and producing a
result at least equal in quality to the other parts of the Premises. When any
Tenant Work is in progress, Tenant shall cause to be maintained insurance as
described in the Tenant Work Insurance Schedule attached as EXHIBITS H AND H1
and such other insurance as may be reasonably required by Landlord covering any
additional hazards due to such Tenant Work, and, if the cost of such Tenant Work
exceeds the Tenant Work Threshold Amount also such bonds or other assurances of
satisfactory completion and payment as Landlord may reasonably require, in each
case for the benefit of Landlord. If the Tenant Work, other than the Finish
Work, in any instance requires Landlord's approval hereunder, Tenant shall
reimburse Landlord for its reasonable costs of reviewing the proposed Tenant
Work and inspecting installation of the same. At all times while performing
Tenant Work, Tenant shall require any Tenant Contractor to comply with all
applicable laws, regulations, permits and Landlord's rules and regulations
relating to such work, including without limitation use of loading areas,
elevators and lobbies. Each Tenant Contractor working on or requiring access to
the roof of the Building shall coordinate their work with the Landlord and
Landlord's roofing contractor, shall comply with its requirements, and shall not
violate existing roof warranties.

     Each Tenant Contractor shall work on the Property without causing labor
disharmony with workers employed by Landlord in undertaking the Base Building
Work, or other work at the Property undertaken by Landlord, from time to time
(and Tenant shall be responsible for all costs required to produce labor
harmony), coordination difficulties, or delay to or impairing of any guaranties,
warranties or the work of any other contractor. Each Tenant Contractor shall, by
entry into the Property, be deemed to have agreed to indemnify and hold the
Indemnitees harmless from any claim, loss or expense arising in whole or in part
out of any act or neglect committed by or under such person while on or about
the Premises or Property to the same extent as Tenant has so agreed in this
Lease, the indemnities of Tenant and Tenant Contractor being joint and several.

     10.05(d) PAYMENT. Tenant shall pay the entire cost of all Tenant Work so
that the Premises, including Tenant's leasehold, shall always be free of liens
for labor or materials. If any such lien is filed that is claimed to be
attributable to Tenant or persons acting under Tenant, then Tenant shall
promptly (and always within thirty (30) days) discharge the same.

     10.05(e) OTHER. Tenant must schedule and coordinate all aspects of work
with the Property manager and Property engineer and shall make prior
arrangements for elevator use with the Property manager. If an operating
engineer is required by any union regulations, Tenant shall pay for such
engineer. If shutdown of risers and mains for electrical, mechanical and
plumbing work is required, such work shall be supervised by Landlord's
representative at Tenant's cost. If special security arrangements must be made
(e.g., in

                                     - 31 -
<Page>

connection with work outside normal business hours), Tenant Contractor shall pay
the actual cost of such security. No work shall be performed in Property
mechanical or electrical equipment rooms without Landlord's approval, which
approval shall not be unreasonably withheld or delayed, and all such work shall
be performed under Landlord's supervision. Except in case of emergency, at least
forty-eight (48) hours' prior notice must be given to the Property management
office prior to the shutdown of fire, sprinkler and other alarm systems, and in
case of emergency, prompt notice shall be given. In the event that such work
unintentionally alerts the Fire or Police Department or any private alarm
monitoring company through an alarm signal, Tenant shall be liable for any fees
or charges levied in connection with such alarm. Tenant shall pay to Landlord
such charges as may from time to time be in effect with respect to any such
shutdown. All demolition, installations, removals or other work that is
reasonably likely to inconvenience other tenants of the Property or disturb
Property operations must be scheduled with the Property manager at least
twenty-four (24) hours in advance.

     Installations within the Premises (and elsewhere where Tenant is permitted
to make installations) shall not interfere with existing services and shall be
installed so as not to unreasonably interfere with subsequent installation of
ceilings or services for other tenants. Redundant electrical, control and alarm
systems and mechanical equipment and sheet metal used or placed on the Property
during construction and not maintained as part of Tenant's use of the Premises
must be removed as part of the work.

     Each Tenant Contractor shall take all reasonable steps to assure that any
work is carried out without disruption from labor disputes arising from disputes
concerning union jurisdiction and the affiliation of workers employed by said
Tenant Contractor or its subcontractors and the union jurisdiction and
affiliation of workers employed by Landlord to undertake the Base Building Work
or other work at the Property undertaken by Landlord from time to time. Tenant
shall be responsible for, and shall reimburse Landlord for, all actual costs and
expenses, including reasonable attorneys' fees incurred by Landlord in
connection with the breach by any Tenant Contractor of such obligations. If
Tenant does not promptly resolve any labor dispute caused by or relating to any
Tenant Contractor, Landlord may in its sole discretion request that Tenant
remove such Tenant Contractor from the Property, and if such Tenant Contractor
is not promptly removed, Landlord may prohibit such Tenant Contractor from
entering the Property.

     Upon completion of any Tenant Work, Tenant shall give to Landlord (i) a
permanent certificate of occupancy (if one is legally required) and any other
final governmental approvals required for such work, (ii) copies of "as built"
plans and all construction contracts and (iii) proof of payment for all labor
and materials.

10.06 CONDITION UPON TERMINATION. At the expiration or earlier termination of
the Term, Tenant (and all persons claiming through Tenant) shall without the
necessity of notice deliver the Premises (including all Finish Work and Tenant
Work, and all

                                     - 32 -
<Page>

replacements thereof, except such additions, alterations, and other Tenant Work
as the Landlord may direct to be removed at the time the Landlord approves the
plans thereof, or, in the case of Tenant Work not subject to Landlord approval,
at the time of expiration or earlier termination of the Term) broom-clean, in
compliance with the requirements of Section 10.07 and in good and tenantable
condition reasonable wear and damage by casualty or taking (to the extent
provided in Article 12 only) excepted. The Premises shall be surrendered to
Landlord free and clear of any mechanic's liens (or any similar lien related to
labor or materials) filed against any part of the Premises and free and clear of
any financing or other encumbrance on any equipment and/or Finish Work or Tenant
Work to be surrendered with the Premises. As part of such delivery, Tenant shall
also provide all keys (or lock combinations, codes or electronic passes) to the
Premises to Landlord; remove all signs wherever located; and, except as provided
in this Section 10.06, remove all Tenant Property and other personal property
whether or not bolted or otherwise attached. As used herein, "TENANT PROPERTY"
shall mean all trade fixtures, furnishings, equipment inventory, and other
personal property owned by Tenant or any person acting under Tenant at the
Premises (except to the extent such fixtures or equipment are paid for out of
the Finish Work Allowance). Tenant shall repair all damage that results from
such removal and restore the Premises substantially to a fully functional and
tenantable condition (including the filling of all floor and wall holes, the
removal of all disconnected wiring back to junction boxes and the replacement of
all damaged ceiling tiles; but excluding (x) the filling of any floor and wall
holes made in connection with tenant improvements that Tenant is permitted or
required to leave in the Premises at the conclusion of the term and (y) the
replacement of any Tenant Property that is being removed from the Premises). Any
property not so removed shall be deemed abandoned, shall at once become the
property of Landlord, and may be disposed of in such manner as Landlord shall
see fit; and Tenant shall pay the cost of removal and disposal to Landlord upon
demand. The covenants of this Section shall survive the expiration or earlier
termination of the Term.

10.07 DECOMMISSIONING OF THE PREMISES. Prior to the expiration of this Lease (or
within thirty (30) days after any earlier termination), Tenant shall clean and
otherwise decommission all interior surfaces (including floors, walls, ceilings,
and counters), piping, supply lines, waste lines and plumbing in and/or
exclusively serving the Premises, and all exhaust or other ductwork in and/or
exclusively serving the Premises, in each case which has carried or released or
been exposed to any Environmental Substances, and shall otherwise clean the
Premises so as to permit the report hereinafter called for by this Section 10.07
to be issued. Prior to the expiration of this Lease (or within thirty (30) days
after any earlier termination), Tenant, at Tenant's expense, shall obtain for
Landlord a report addressed to Landlord (and, at Tenant's election, Tenant) by a
reputable licensed environmental engineer that is designated by Tenant and
acceptable to Landlord in Landlord's reasonable discretion, which report shall
be based on the environmental engineer's inspection of the Premises and shall
show:

                                     - 33 -
<Page>

     (i)   that the Environmental Substances, to the extent, if any, existing
prior to such decommissioning, have been removed as necessary so that the
interior surfaces of the Premises (including floors, walls, ceilings, and
counters), piping, supply lines, waste lines and plumbing, and all such exhaust
or other ductwork in and/or exclusively serving the Premises, may be reused by a
subsequent tenant or disposed of in compliance with applicable Environmental
Laws (as defined in Section 9.04 hereof) without taking any special precautions
for Environmental Substances, without incurring special costs or undertaking
special procedures for demolition, disposal, investigation, assessment, cleaning
or removal of Environmental Substances and without incurring regulatory
compliance requirements or giving notice in connection with Environmental
Substances; and

     (ii)   that the Premises may be reoccupied for office or laboratory use,
demolished or renovated without taking any special precautions for Environmental
Substances, without incurring special costs or undertaking special procedures
for disposal, investigation, assessment, cleaning or removal of Environmental
Substances and without incurring regulatory requirements or giving notice in
connection with Environmental Substances.

     Further, for purposes of clause (ii): "SPECIAL COSTS" or "SPECIAL
PROCEDURES" shall mean costs or procedures, as the case may be, that would not
be incurred but for the nature of the Environmental Substances as Environmental
Substances instead of non-hazardous materials. The report shall include
reasonable detail concerning the clean-up location, the tests run and the
analytic results.

     If Tenant fails to perform its obligations under this Section, without
limiting any other right or remedy, Landlord may, on five (5) business days'
prior written notice to Tenant, perform such obligations at Tenant's expense,
and Tenant shall promptly reimburse Landlord upon demand for all costs and
expenses reasonably incurred together with an Administrative Charge. Tenant's
obligations under this Section shall survive the expiration or earlier
termination of this Lease.

ARTICLE 11: ROOFTOP LICENSE

11.01 ROOFTOP LICENSE. If requested by Tenant in writing and required to
construct Tenant Work shown on any Construction Documents approved by Landlord,
Landlord shall grant Tenant the appurtenant, exclusive, and irrevocable (except
upon the expiration or earlier termination of this Lease) right at no additional
charge, but otherwise subject to the terms and conditions of this Lease, to use
a contiguous portion of the roof of the Building approved by Landlord (the
"ROOFTOP INSTALLATION AREAS") to operate, maintain, repair and replace rooftop
mechanical equipment appurtenant to the Permitted Uses installed as part of the
Finish Work or otherwise as permitted pursuant to Section 10.05 ("TENANT'S
EQUIPMENT"). The exact location and layout of the Rooftop Installation Areas
shall be approved by Landlord in its sole

                                     - 34 -
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discretion and shall not exceed in area the Tenant's Pro Rata Share of rooftop
areas made available to tenants in the Building for similar purposes.

11.02 INSTALLATION AND MAINTENANCE OF ROOFTOP EQUIPMENT. Tenant shall install
Tenant's Equipment at its sole cost and expense, at such times and in such
manner as Landlord may reasonably designate and in accordance with all of the
applicable provisions of this Lease regarding Tenant Work. Tenant shall not
install or operate Tenant's Equipment until it receives prior written approval
of the Construction Documents in accordance with Section 10.05(b). Landlord may
withhold approval if the installation or operation of Tenant's Equipment
reasonably would be expected to damage the structural integrity of the Building.

     Tenant shall engage Landlord's roofer before beginning any rooftop
installations or repairs of Tenant's Equipment, whether under this Article 11 or
otherwise, and shall always comply with the roof warranty governing the
protection of the roof and modifications to the roof. Tenant shall obtain a
letter from Landlord's roofer following completion of such work stating that the
roof warranty remains in effect. Tenant, at its sole cost and expense, shall
inspect the Rooftop Installation Areas at least once a month and correct any
loose bolts, fittings or other appurtenances and shall repair any damage to the
roof caused by the installation or operation of Tenant's Equipment. Tenant
covenants that the installation, existence, maintenance and operation of
Tenant's Equipment shall not violate any Legal Requirements or constitute a
nuisance. Tenant shall pay Landlord following a written request therefor, with
the next payment of Rent, (i) all applicable taxes or governmental charges,
fees, or impositions imposed on Landlord because of Tenant's use of the Rooftop
Installation Areas and (ii) the amount of any increase in Landlord's insurance
premiums as a result of the installation of Tenant's Equipment.

11.03 INDEMNIFICATION. Tenant agrees that the installation, operation and
removal of Tenant's Equipment shall be at its sole risk. Tenant shall indemnify
and defend Landlord and the other Indemnitees against any liability, claim or
cost, including reasonable attorneys' fees, incurred in connection with the loss
of life, personal injury, damage to property or business or any other loss or
injury (except to the extent due to the negligence or willful misconduct of
Landlord or its employees, agents, contractors or invitees) arising out of the
installation, use, operation, or removal of Tenant's Equipment by Tenant or its
employees, agents, contractors, or invitees, including any liability arising out
of Tenant's violation of this Article 11. Landlord assumes no responsibility for
interference in the operation of Tenant's Equipment caused by other tenants'
equipment, or for interference in the operation of other tenants' equipment
caused by Tenant's Equipment. The provisions of this Section 11.03 shall survive
the expiration or earlier termination of this Lease.

11.04 REMOVAL OF TENANT'S EQUIPMENT. Upon the expiration or earlier termination
of the Lease, Tenant, at its sole cost and expense, shall (i) remove Tenant's
Equipment from the Rooftop Installation Areas, if necessary, in accordance with
the provisions of this Lease regarding Tenant Work and (ii) leave the Rooftop
Installation Areas in good order and repair,

                                     - 35 -
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reasonable wear and tear excepted. If Tenant does not remove Tenant's Equipment
when so required, Landlord may remove and dispose of it and charge Tenant for
all costs and expenses incurred. Notwithstanding clause (i) to the contrary,
Tenant may request, at the time it seeks approval from Landlord for the
installation of any Tenant's Equipment, that Landlord identify which, if any, of
such Tenant's Equipment must be removed at the expiration or earlier termination
of the Lease.

11.05 INTERFERENCE BY TENANT'S EQUIPMENT. Landlord may grant future roof rights
to other parties, and Landlord shall be contractually obligated to cause such
other parties to minimize interference with Tenant's Equipment. If Tenant's
Equipment (i) causes physical damage to the structural integrity of the
Building, (ii) materially interferes with any telecommunications, mechanical or
other systems located at or servicing (as of the Lease Commencement Date) the
Building or any building, premises or location in the vicinity of the Building,
(iii) interferes with any other service provided to other tenants in the
Building by rooftop installations installed prior to the installation of
Tenant's Equipment or (iv) interferes with any other tenants' business, in each
case in excess of that permissible under F.C.C. or other regulations (to the
extent that such regulations apply and do not require such tenants or those
providing such services to correct such interference or damage), Tenant shall
within two (2) Business Days of notice (which may be oral) of a claim of
interference or damage cooperate with Landlord or any other tenant or third
party making such claim to determine the source of the damage or interference
and effect a prompt solution at Tenant's expense (if Tenant's Equipment caused
such interference or damage). In the event Tenant disputes Landlord's allegation
that Tenant's Equipment is causing a problem with the Building (including, but
not limited to, the electrical, HVAC, and mechanical systems of the Building)
and/or any other Building tenants' equipment in the Building, in writing
delivered within two (2) Business Days of receiving Landlord's notice claiming
such interference, then Landlord and Tenant shall meet to discuss a solution,
and if within seven (7) days of their initial meeting Landlord and Tenant are
unable to resolve the dispute, then the matter shall be submitted to arbitration
in accordance with the provisions set forth below.

     The parties shall direct the Boston office of the American Arbitration
Association (the "AAA") to appoint an arbitrator who shall have a minimum of ten
(10) years' experience in commercial real estate disputes and who shall not be
affiliated with either Landlord or Tenant. Both Landlord and Tenant shall have
the opportunity to present evidence and outside consultants to the arbitrator.

     The arbitration shall be conducted in accordance with the commercial real
estate arbitration rules of the AAA insofar as such rules are not inconsistent
with the provisions of this Lease (in which case the provisions of this Lease
shall govern). The cost of the arbitration (exclusive of each party's witness
and attorneys' fees, which shall be paid by such party) shall be borne equally
by the parties.

                                     - 36 -
<Page>

     Within ten (10) days of appointment, the arbitrator shall determine whether
or not Tenant's Equipment is causing a problem with the Building and/or any
other Building tenants' equipment in the Building, and the appropriate
resolution, if any. The arbitrator's decision shall be final and binding on the
parties. If Tenant shall fail to cooperate with Landlord in resolving any such
interference or if Tenant shall fail to implement the arbitrator's decision
within ten (10) days after it is issued, Landlord may at any time thereafter (i)
declare an Event of Default and pursue the remedies set forth in Section 14 of
this Lease and/or (ii) relocate the item(s) of Tenant's Equipment in dispute in
a manner consistent with the arbitral decision.

11.06 RELOCATION OF TENANT'S EQUIPMENT. Based on Landlord's good faith
determination that such a relocation is necessary, Landlord reserves the right
to cause Tenant to relocate Tenant's Equipment located on the roof to comparably
functional space on the roof by giving Tenant prior notice of such intention to
relocate. If within thirty (30) days after receipt of such notice Tenant has not
agreed with Landlord on the space to which Tenant's Equipment is to be
relocated, the timing of such relocation, and the terms of such relocation, then
Landlord shall have the right to make all such determinations in its reasonable
judgment. Landlord agrees to pay the reasonable cost of moving Tenant's
Equipment to such other space, taking such other steps necessary to ensure
comparable functionality of Tenant's Equipment, and finishing such space to a
condition comparable to the then condition of the current location of Tenant's
Equipment. Such payment by Landlord shall not constitute an Operating Expense
under this Lease. Tenant shall arrange for the relocation of Tenant's Equipment
within sixty (60) days after a comparable space is agreed upon or selected by
Landlord, as the case may be. In the event Tenant fails to arrange for said
relocation within the sixty-(60)-day period, Landlord shall have the right to
arrange for the relocation of Tenant's Equipment at Landlord's expense, all of
which shall be performed in a manner designed to minimize interference with
Tenant's business.

ARTICLE 12: DAMAGE OR DESTRUCTION; CONDEMNATION

12.01 DAMAGE OR DESTRUCTION OF PREMISES. If the Premises or any part thereof
shall be damaged by fire or other insured casualty, then, subject to the last
paragraph of this Section, Landlord shall proceed with diligence, subject to
then applicable statutes, building codes, zoning ordinances and regulations of
any governmental authority, and at the expense of Landlord (but only to the
extent of insurance proceeds made available to Landlord by any mortgagee of the
Building and any ground lessor) to repair or cause to be repaired such damage,
(other than any Tenant Work, which Tenant shall promptly commence, and proceed
with diligence, to restore). All repairs to and replacements of Tenant Property
and any Tenant Work shall be made by and at the expense of Tenant. The cost of
any repairs performed under this Section by Landlord at Tenant's expense
(including costs of design fees, financing, and charges for administration,
overhead and construction management services by Landlord and Landlord's
contractor) shall constitute Additional Rent hereunder. If the Premises or any
part thereof shall have been rendered unfit for use and

                                     - 37 -
<Page>

occupation hereunder by reason of such damage, the Base Rent or a just and
proportionate part thereof, according to the nature and extent to which the
Premises shall have been so rendered unfit, shall be abated until the Premises
(except as to Tenant Property and any Tenant Work) shall have been restored as
nearly as practicable to the condition in which they were immediately prior to
such fire or other casualty; provided, however, that in no event shall the
period of such abatement exceed 14 months, and that if and to the extent
Landlord shall be unable to collect the insurance proceeds (including rent
insurance proceeds) applicable to such damage because of some action or inaction
on the part of Tenant, or the employees, licensees or invitees of Tenant, the
cost of repairing such damage shall be paid by Tenant and there shall be no
abatement of rent. Landlord shall not be liable for delays in the making of any
such repairs that are due to government regulation, casualties, and strikes,
unavailability of labor and materials, delays in obtaining insurance proceeds,
and other causes beyond the reasonable control of Landlord, nor shall Landlord
be liable for any inconvenience or annoyance to Tenant or injury to the business
of Tenant resulting from delays in repairing such damage.

     If (i) the Premises are so damaged by fire or other casualty (whether or
not insured) at any time during the last thirty (30) months of the Term that the
cost to repair such damage is reasonably estimated to exceed one-third of the
total Base Rent payable hereunder for the period from the estimated completion
date of repair until the end of the Term, (ii) at any time the Property (or any
portion thereof, whether or not including any portion of the Premises) is so
damaged by fire or other casualty (whether or not insured) that substantial
alteration or reconstruction or demolition of the Property (or a portion
thereof) shall in Landlord's judgment be required, or (iii) at any time damage
to the Building occurs by fire or other insured casualty and any mortgagee or
ground lessor shall refuse to permit insurance proceeds to be utilized for the
repair or replacement of such property and Landlord determines not to repair
such damage, then and in any of such events, this Lease and the term hereof may
be terminated at the election of Landlord by a notice from Landlord to Tenant
within six (6) months, or such longer period as is required to complete
arrangements with any mortgagee or ground lessor regarding such situation,
following such fire or other casualty; the effective termination date pursuant
to such notice shall be not less than thirty (30) days after the day on which
such termination notice is received by Tenant. If any mortgagee refuses without
fault by Tenant to permit insurance proceeds to be applied to replacement of the
Premises, and neither Landlord nor such mortgagee has commenced such replacement
within one hundred forty (140) days following adjustment of such casualty loss
with the insurer, then Tenant may, until any such replacement commences,
terminate this Lease by giving at least thirty (30) days prior written notice
thereof to Landlord and such termination shall be effective on the date
specified if such replacement has not then commenced. If Landlord has not
completed any restoration of the Premises that it is required to complete
pursuant to this Section 12.01 within fourteen (14) months following adjustment
of such casualty loss with the insurer, then Tenant may terminate this Lease by
thirty (30) days prior written notice to Landlord, provided that such notice
shall be null and void, and this Lease shall remain in full force

                                     - 38 -
<Page>

and effect, if such restoration is completed within such 30 day period. In the
event of any termination, the Term shall expire as though such effective
termination date were the date originally stipulated in Article 1 for the end of
the Term and the Base Rent and Additional Rent for Total Operating Costs (to the
extent not abated as set forth above) shall be apportioned as of such date.

12.02 EMINENT DOMAIN. In the event that all or any substantial part of the
Premises or the Property or its common areas is taken (other than for temporary
use, hereafter described) by public authority under power of eminent domain (or
by conveyance in lieu thereof), then by notice given within three months
following the recording of such taking (or conveyance) in the appropriate
registry of deeds, this Lease may be terminated at Landlord's election thirty
(30) days after such notice, and Base Rent and Tenant's share of Total Operating
Costs, shall be apportioned as of the date of termination. If this Lease is not
terminated as aforesaid, subject to the rights of mortgagees Landlord shall
within a reasonable time thereafter, diligently restore what may remain of the
Premises (excluding any Tenant Property or other items installed or paid for by
Tenant that Tenant is permitted or may be required to remove upon expiration and
any Tenant Work) to a tenantable condition. In the event some portion of
rentable floor area of the Premises is taken (other than for temporary use) and
this Lease is not terminated, Base Rent shall be proportionally abated for the
remainder of the Term. In the event of any taking of the Premises or any part
thereof for temporary use, (i) this Lease shall be and remain unaffected thereby
and rent shall not abate, and (ii) Tenant shall be entitled to receive for
itself such portion or portions of any award made for such use with respect to
the period of the taking that is within the Term, provided that if such taking
shall remain in force at the expiration or earlier termination of this Lease,
then Tenant shall pay to Landlord a sum equal to the reasonable cost of
performing Tenant's obligations hereunder with respect to surrender of the
Premises and upon such payment shall be excused from such obligations.

     So long as Tenant is not then in breach of any covenant or condition of
this Lease, any specific damages that are expressly awarded to Tenant on account
of its relocation expenses, and specifically so designated, shall belong to
Tenant. Except as provided in the preceding sentence of this paragraph, Landlord
reserves to itself, and Tenant releases and assigns to Landlord, all rights to
damages accruing on account of any taking or by reason of any act of any public
authority for which damages are payable. Tenant agrees to execute such further
instruments of assignment as may be reasonably requested by Landlord, and to
turn over to Landlord any damages that may be recovered in any proceeding or
otherwise; and Tenant irrevocably appoints Landlord as its attorney-in-fact with
full power of substitution so to execute and deliver in Tenant's name, place and
stead all such further instruments if Tenant shall fail to do so after ten (10)
days' notice.

ARTICLE 13: ASSIGNMENT AND SUBLETTING

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13.01 LANDLORD'S CONSENT REQUIRED. Except as set forth in this Article, Tenant
shall not directly or indirectly assign this Lease, or sublet or license the
Premises or any portion thereof, or advertise the Premises for assignment or
subletting or permit the occupancy of all or any portion of the Premises by any
person other than Tenant (each of the foregoing actions are collectively
referred to as a "TRANSFER") without obtaining, on each occasion, the prior
written consent of Landlord, which consent shall not be unreasonably withheld,
conditioned or delayed, provided that Tenant complies with the provisions of
this Article. It shall be reasonable for Landlord to withhold consent if a
proposed assignee or a subtenant (or subtenants) that in the aggregate would
sublease greater than fifty percent (50%) of the Premises, does not or do not
have a creditworthiness that is acceptable to Landlord in light of the
obligations being assumed by the Transferee. A Transfer shall include, without
limitation, any transfer of Tenant's interest in this Lease by operation of law,
merger or consolidation of Tenant into any other firm or corporation, and the
transfer or sale of a controlling interest in Tenant, whether by sale of its
capital stock or otherwise or any sale of all or a substantial part of Tenant's
assets. Any Transfer shall be subject to this Lease, all of the provisions of
which shall be conditions to such Transfer and be binding on any assignee,
subtenant, or other occupant (any of the foregoing, a "Transferee"). No
Transferee shall have any right further to transfer its interest in the Premises
except back to Tenant, and nothing herein shall impose any obligation on
Landlord to consider any request for a further Transfer. In no event shall
Tenant propose, or enter into, a Transfer (other than a Related Party Transfer,
as defined below) during the first 24 months of the Term.

13.02 TERMS. Tenant shall not offer to make a Transfer (i) to any tenant in the
Property or any prospective tenant with whom Landlord has commenced negotiations
for space (or any affiliate of such tenant or prospective tenant) in the
Building, (ii) to any person or entity that would be of such type, character or
condition as to be inappropriate as a tenant of a building comparable to the
Building, or (iii) until such time as one hundred percent (100%) of the Building
is leased for a term of years, unless the aggregate rent payable to Tenant under
such Transfer equals or exceeds the prevailing market rate rent and other
charges quoted by Landlord for space in the Building comparable to the Premises.

13.03 RIGHT OF TERMINATION OR RECAPTURE. If Tenant proposes a Transfer of all or
more than fifty percent (50%) of the Premises in the aggregate (excluding any
Related Party Transfer), in Tenant's request for consent under Section 13.04
Tenant shall offer to Landlord in writing the right to terminate this Lease as
to the area in question. If Landlord shall elect in writing to accept the offer
to terminate within thirty (30) days after receipt of such offer, this Lease
shall so terminate as to the area in question of the date specified in such
offer as of the date specified in the offer and the provisions of this Lease
governing termination shall apply to such space. If Landlord shall not so elect,
Tenant shall then comply with the provisions of this Article applicable to a
Transfer. Landlord shall have the right to separate any portion of the Premises
recaptured pursuant to this Section 13.03 from the remainder of the Premises by
constructing demising walls at its sole cost and expense.

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<Page>

13.04 PROCEDURES. Tenant's request for consent under this Article shall set
forth the details of the proposed Transfer, including: (i) the name, business,
and financial condition of the prospective transferee, (ii) a true and complete
copy of the proposed instrument containing all of the terms and conditions of
such Transfer, (iii) a written agreement of the assignee, subtenant or licensee
agreeing with Landlord to perform and observe all of the terms, covenants, and
conditions of this Lease undertaken by such transferee and such other matters as
are contained in Landlord's standard form of consent to a Transfer, which shall
be substantially the same as the form attached hereto as Exhibit P with respect
to subleases, and (iv) any other information Landlord reasonably deems relevant
in light of the provisions of this Article 13. Subject to the foregoing
provisions of this Article VI, Landlord's consent to a proposed sublease of all
or part of the Premises shall not be unreasonably withheld. Tenant shall pay to
Landlord, as Additional Rent, Landlord's reasonable attorneys' fees in reviewing
any proposed Transfer, whether or not Landlord consents and whether or not
Landlord's consent is required. Notwithstanding anything to the contrary in this
Article 13, Tenant may make a Related Party Transfer without the consent of
Landlord provided that Tenant gives Landlord at least ten (10) days' prior
notice thereof together with evidence reasonably satisfactory to Landlord that
the proposed Transfer is a Related Party Transfer and such Related Party
Transfer is subject to all of the other terms and conditions of this Article. A
"RELATED PARTY TRANSFER" shall mean one or more of the following: (1) a sublease
to any subsidiary in which Tenant owns substantially all voting stock and
control or to any parent owning substantially all voting stock and control of
Tenant, (2) any assignment incident to the sale of substantially all of Tenant's
assets, or (3) a statutory merger of Tenant with any other entity, provided that
in either case of clause (2) or (3) the person succeeding to Tenant's interest
immediately thereafter has a net worth equal to or in excess of that of Tenant
at the Date of Lease or immediately prior to the Related Party Transfer,
whichever is greater.

13.05 EXCESS RENTS. If the consideration, rent, or other amounts payable to
Tenant under any other Transfer including Transfers consented to by Landlord
(but excluding any Related Party Transfer) exceed the Rent and other charges to
be paid hereunder and Tenant's Transfer Expenses (pro rated based (a) on floor
area in the case of a subletting, license or other occupancy of less than the
entire area of the Premises and (b) over the remaining Term), then Tenant shall
pay to Landlord, as Additional Rent, fifty percent (50%) of the amount of such
excess when and as received. Tenant's "TRANSFER EXPENSES" shall mean Tenant's
reasonable and necessary payments to third parties in connection with such a
Transfer on account of brokerage, legal and fit-up costs. Without limiting the
generality of the first sentence of this section, any lump-sum payment or series
of payments (including for the purchase or use of so-called leasehold
improvements to the extent such leasehold improvements will become the property
of Landlord upon the termination or earlier expiration of this Lease) on account
of any Transfer shall be deemed to be in excess of rent and other charges in its
or their entirety and profit on account of such lump sum payments shall mean the
extent to which such lump sum payments exceed the sum of (x)

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the present value of the Rent and other charges to be paid hereunder discounted
at the rate of four percent (4%) and (y) Tenant's Transfer Expenses (pro rated
based (a) on floor area in the case of a subletting, license or other occupancy
of less than the entire area of the Premises and (b) over the remaining Term).

13.06 NO RELEASE Notwithstanding any Transfer and whether or not the same is
consented to, the liability of Tenant to Landlord shall remain direct and
primary. Any transferee of all or substantially all of Tenant's interest in the
Premises shall be jointly and severally liable with Tenant to Landlord for the
performance of all of Tenant's covenants under this Lease; and such assignee
shall upon request execute and deliver such instruments as Landlord reasonably
requests in confirmation thereof (and agrees that its failure to do so shall
be a default). Tenant hereby irrevocably authorizes Landlord to collect Rent and
other charges from any Transferee (and upon notice any Transferee shall pay
directly to Landlord) and apply the net amount collected to the rent and other
charges reserved under this Lease. No Transfer shall be deemed a waiver of the
provisions of this Section, or the acceptance of the Transferee as a tenant, or
a release of Tenant from direct and primary liability for the performance of all
of the covenants of this Lease. The consent by Landlord to any Transfer shall
not relieve Tenant or any transferee from the obligation of obtaining the
express consent of Landlord to any modification of such Transfer or a further
Transfer by Tenant or such transferee. Notwithstanding anything to the contrary
in the documents effecting the Transfer, Landlord's consent shall not alter in
any manner whatsoever the terms of this Lease, to which any Transfer at all
times shall be subject and subordinate; provided that (other than in the case of
a Related Party Transfer or as otherwise expressly provided herein) any option
or other right that Tenant may have relating to the Premises, including any
right to extend the Term or lease other premises, shall automatically be
terminated. The breach by Tenant or any transferee of any covenant in this
Article shall be a default for which there is no cure period. Landlord shall not
have any liability to Tenant for any failure or refusal by Landlord to consent
to a proposed Transfer, and Tenant's sole remedy for any such failure or refusal
shall be for injunctive relief after a judicial determination that Landlord has
breached any obligation to grant such consent required to be given hereunder.

     Anything contained in the foregoing provisions of this section to the
contrary notwithstanding, neither Tenant nor any transferee nor any other person
having an interest in the possession, use, occupancy or utilization of the
Premises shall enter into any lease, sublease, assignment, license, concession
or other agreement for use, occupancy or utilization of space in the Premises
that provides for rental or other payment for such use, occupancy or utilization
based, in whole or in part, on the net income or profits derived by any person
from the Premises leased, used, occupied or utilized (other than an amount based
on a fixed percentage or percentages of receipts or sales), and any such
purported lease, sublease, assignment, license, concession or other agreement
shall be absolutely void and ineffective as a conveyance of any right or
interest in the possession, use, occupancy or utilization of any part of the
Premises.

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<Page>

     13.07. TERMINATION UPON ASSIGNMENT Notwithstanding anything to the contrary
in this Lease, Tenant shall have the one-time right to terminate the term of
this Lease effective upon the date (the "DISSOLUTION TERMINATION DATE") that (x)
the original Tenant named hereunder dissolves or otherwise ceases to exists as
the result of a merger or (y) substantially all of Tenant's assets are acquired
in a bona fide sale to an unrelated third party; provided, however, that (A)
such termination shall only take effect if Tenant gives Landlord at lease nine
months' prior written notice (a "MERGER/SALE TERMINATION NOTICE") of the
Dissolution Termination Date and (B) in no event shall the Dissolution
Termination Date occur on a date that is later than the last day of the fifth
Lease Year of the term. The Termination Notice must be accompanied by a check
payable to Landlord in an amount equal to the Termination Payment (calculated
and subject to the minimum amount set forth in Section 3.04 as if the
Dissolution Termination Date is the Early Termination Date) and (y) a warrant,
effective upon the date of the Merger/Sale Termination Notice, to purchase
10,000 shares of Tenant's common stock at an exercise price of $2.70 per share
in the form attached to the lease as EXHIBIT N. The Termination Payment shall be
in addition to, and not in lieu of, Tenant's obligations to pay rent for the
period ending on the Dissolution Termination Date. Time is of the essence with
regard to the provisions of this Section 13.07.

     Tenant's Dissolution Termination Notice shall be effective only if such
notice is applicable to the entire Premises, is unconditional, and is
accompanied by the Termination Payment. Once given, such termination notice
shall be irrevocable. Notwithstanding the foregoing, any exercise by Tenant of
its termination right under this Paragraph shall, at Landlord's election, be
void if Tenant is in default hereunder continuing beyond applicable notice or
cure period or an event or condition exists which with notice and the passage of
time would constitute such a default, provided that, in either case, any such
default is with respect to a payment of Rent or is on account of a breach of the
terms and conditions of Section 9.04 or Section 13.01 of this Lease unless
Tenant cures such default within the applicable cure period, if any, under this
Lease (or unless Tenant otherwise provides Landlord with sufficient assurances
that Tenant will complete such cure as determined in Landlord's sole
discretion), either at the time Tenant elects to terminate the Lease or at the
time the Lease would be terminated pursuant to Tenant's election to terminate.
If Tenant exercises its termination right hereunder, (a) Tenant's extension
option under Section 3.03. and rights pursuant to Article 18 shall be null and
void, and (b) Tenant shall peaceably surrender the Premises to Landlord on or
before the Dissolution Termination Date in accordance with the applicable
provisions of the Lease.

ARTICLE 14: EVENTS OF DEFAULT AND REMEDIES

14.01 EVENTS OF DEFAULT. If Tenant fails to pay Rent when due and such default
continues for five (5) business days after notice, or if more than two default
notices are properly given in any twelve-month period; or if Tenant vacates
substantially all of the Premises

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<Page>

with more than six months of the Term remaining; or if Tenant vacates
substantially all of the Premises with six months or less of the Term remaining
and Tenant is then, or is thereafter, in default pursuant to any other provision
of this Lease following the giving of applicable notices, if any; or if Tenant
(or any Transferee) dissolves or otherwise ceases to do business in the
Commonwealth of Massachusetts; or if Tenant (or any Transferee) makes any
transfer of the Premises in violation of this Lease; or if a petition is filed
by Tenant (or any Transferee) for insolvency or for appointment of a receiver,
trustee or assignee or for adjudication, reorganization or arrangement under any
bankruptcy act, or if any similar petition is filed against Tenant (or any
Transferee) and such petition filed against is not dismissed within thirty (30)
days thereafter; or if any representation or warranty made by Tenant is untrue
in any material respect; or if Tenant fails to perform any other covenant or
condition hereunder and such default continues longer than any period expressly
provided for the correction thereof (and if no period is expressly provided then
for thirty (30) days after notice is given, provided, however, that such period
shall be reasonably extended in the case of any such non-monetary default that
cannot be cured within such period only if the matter complained of can be
cured, Tenant begins promptly and thereafter diligently completes the cure, and
Tenant gives Landlord notice of such intent to cure within ten (10) days after
notice of such default), or if the stock warrant (the "WARRANT") in the form of
EXHIBIT M (the "INITIAL WARRANT") issued by Tenant to Landlord shall cease to be
in full force and effect, or if the issuer of the Initial Warrant shall be in
default under the Warrant beyond the expiration of any applicable cure period,
then, and in any such case, Landlord and its agents lawfully may, in addition to
any remedies for any preceding breach, immediately or at any time thereafter
without demand or notice and with or without process of law, enter upon any part
of the Premises in the name of the whole or mail or deliver a notice of
termination of the Term of this Lease addressed to Tenant at the Premises or any
other address herein, and thereby terminate the Term and repossess the Premises
as of Landlord's former estate. Any default beyond applicable notice and cure
periods by Tenant is referred to herein as an "EVENT OF DEFAULT." At Landlord's
election such notice of termination may be included in any notice of default.
Upon such entry or mailing the Term shall terminate, all executory rights of
Tenant and all obligations of Landlord will immediately cease, and Landlord may
expel Tenant and all persons claiming under Tenant and remove their effects
without any trespass and without prejudice to any remedies for arrears of Rent
or prior breach; and Tenant waives all statutory and equitable rights to its
leasehold (including rights in the nature of further cure or redemption, if
any). If Landlord engages attorneys in connection with any failure to perform by
Tenant hereunder, Tenant shall reimburse Landlord for the fees of such attorneys
on demand as Additional Rent. Without implying that other provisions do not
survive, the provisions of this Article shall survive the Term or earlier
termination of this Lease.

     Rent forgiveness, allowances for (and/or Landlord expenses in designing and
constructing) leasehold improvements to ready the Premises for Tenant's
occupancy and the like, if any, have been agreed to by Landlord as inducements
for Tenant faithfully to perform all of its obligations. For all purposes, upon
the occurrence of any default and the

                                     - 44 -
<Page>

lapse of the applicable cure period, if any, any such inducements shall be
deemed void as of the date hereof as though such had never been included (except
to the extent previously received by Tenant); e.g., Tenant shall have no further
right to any then unused amounts of Finish Work Allowance or to any then
unapplied free rent or Rent credit. The foregoing will occur automatically
without any further notice by Landlord, whether or not the Term is then or
thereafter terminated and whether or not Tenant thereafter corrects such
default.

14.02 REMEDIES FOR DEFAULT.

     14.02(a) RELETTING EXPENSES DAMAGES. If the Term of this Lease is
terminated for default, and Landlord relets the Premises within ninety (90) days
of lease termination, Landlord shall be entitled to deduct from any credit due
Tenant under Section 14.02(b) all of Landlord's reasonable costs, including
reasonable attorneys fees, related to Tenant's default and in collecting amounts
due and all reasonable expenses in connection with reletting, including tenant
inducements to new tenants, brokerage commissions, fees for legal services,
expenses of preparing the Premises for reletting and the like together with an
administrative charge of 5% of all the foregoing costs ("RELETTING EXPENSES").
If Landlord does not relet the Premises within ninety (90) days of lease
termination, Tenant covenants, as an additional cumulative obligation after such
ninety (90) day period, to pay Landlord's Reletting Expenses as and when
incurred, and upon demand. It is agreed that Landlord may (i) relet the Premises
or part or parts thereof for a term or terms that may be equal to, less than or
exceed the period that would otherwise have constituted the balance of the Term,
and may grant such tenant inducements, including free rent, as Landlord in its
sole discretion considers advisable, and (ii) make such alterations to the
Premises as Landlord in its sole discretion considers advisable, and no failure
to relet or to collect rent under any reletting shall operate to reduce Tenant's
liability. Any obligation to relet imposed by law will be subject to Landlord's
reasonable objectives of developing its property in a harmonious manner with
appropriate mixes of tenants, uses, floor areas, terms and the like.

     14.02(b) TERMINATION DAMAGES. If the Term of this Lease is terminated for
default, unless and until Landlord elects lump sum liquidated damages described
in the next paragraph, Tenant covenants, as an additional, cumulative obligation
after any such termination, to pay punctually to Landlord all the sums and
perform all of its obligations in the same manner as if the Term had not been
terminated. In calculating such amounts Tenant will be credited with the net
proceeds of any rent then actually received by Landlord from a reletting of the
Premises after deducting all Reletting Expenses (unless such sums have
previously been paid pursuant to Section 14.02(a)), provided that Tenant shall
never be entitled to receive any portion of the re-letting proceeds, even if the
same exceed the Rent originally due hereunder.

     14.02(c) LUMP SUM LIQUIDATED DAMAGES. If this Lease is terminated for
default, Tenant covenants, as an additional, cumulative obligation after any
such termination, to pay forthwith to Landlord at Landlord's election made by
written notice at any time after

                                     - 45 -
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termination, as liquidated damages a single lump sum payment equal to THE SUM OF
(i) all sums to be paid by Tenant and not then paid at the time of such
election, PLUS EITHER, as Landlord elects, (ii) the excess of the present value
of all of the Rent reserved for the residue of the Term (with Additional Rent
deemed to increase 4% in each year on a compounding basis) over the present
value of the aggregate fair market rent and Additional Rent payable (if less
than the Rent payable hereunder) on account of the Premises during such period,
which fair market rent shall be reduced by reasonable projections of vacancies
and by Landlord's Reletting Expenses described above to the extent not
theretofore paid to Landlord), or (iii) an amount equal to the sum of all of the
Rent and other sums due under the Lease with respect to the twelve (12)-month
period next following the date of termination. (The Federal Reserve discount
rate (or equivalent) shall be used in calculating such present values under
clause (ii), and in the event the parties are unable to agree on such fair
market rent, the matter shall be submitted, upon the demand of either party, to
the office of the American Arbitration Association (or successor) closest to the
Property, with a request for arbitration in accordance with the rules of the
Association by a single arbitrator who shall be a licensed real estate broker
with at least 10 years experience in the leasing of 1,000,000 or more square
feet of floor area of buildings similar in character and location to the
Premises, whose decision shall be conclusive and binding on the parties.)

     14.02(d) REMEDIES CUMULATIVE; JURY WAIVER; LATE PERFORMANCE. The remedies
to which Landlord may resort under this Lease, and all other rights and remedies
of Landlord are cumulative, and any two or more may be exercised at the same
time. Nothing in this Lease shall limit the right of Landlord to prove and
obtain in proceedings for bankruptcy or insolvency an amount equal to the
maximum allowed by any statute or rule of law in effect at the time; and Tenant
agrees that the fair value for occupancy of all or any part of the Premises at
all times shall never be less than the Base Rent and all Additional Rent payable
from time to time. Tenant shall also indemnify and hold Landlord harmless in the
manner provided elsewhere herein if Landlord shall become or be made a party to
any claim or action (a) instituted by Tenant against any third party, or by any
third party against Tenant, or by or against any person claiming Tenant; (b) for
foreclosure of any lien for labor or material furnished to or for Tenant or such
other person; (c) otherwise arising out of or resulting from any act or
transaction of Tenant or such other person; or (d) necessary to protect
Landlord's interest under this Lease in a bankruptcy proceeding, or other
proceeding under Title 11 of the United States Code, as amended. LANDLORD AND
TENANT WAIVE TRIAL BY JURY IN ANY ACTION TO WHICH THEY ARE PARTIES, and further
agree that any action arising out of this Lease (except an action for possession
by Landlord, which may be brought in whatever manner or place provided by law)
shall be brought in the Trial Court, Superior Court Department, in the county
where the Premises are located.

     14.02(e) WAIVERS OF DEFAULT; ACCORD AND SATISFACTION. No consent by
Landlord or Tenant to any act or omission that otherwise would be a default
shall be construed to permit other similar acts or omissions. Neither party's
failure to seek redress for violation

                                     - 46 -
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or to insist upon the strict performance of any covenant, nor the receipt by
Landlord of Rent with knowledge of any breach of covenant, shall be deemed a
consent to or waiver of such breach. No breach of covenant shall be implied to
have been waived unless such is in writing, signed by the party benefiting from
such covenant and delivered to the other party; and no acceptance by Landlord of
a lesser sum than the Rent due shall be deemed to be other than on account of
the earliest installment of such Rent. Nor shall any endorsement or statement on
any check or in any letter accompanying any check or payment be deemed an accord
and satisfaction; and Landlord may accept such check or payment without
prejudice to Landlord's right to recover the balance of such installment or
pursue any other right or remedy. The delivery of keys (or any similar act) to
Landlord shall not operate as a Termination of the Term or an acceptance or
surrender of the Premises. The acceptance by Landlord of any Rent following the
giving of any default and/or termination notice shall not be deemed a waiver of
such notice. Tenant shall not interpose any counterclaim or counterclaims in a
summary proceeding or in any action based on non-payment of Rent.

     14.02(f) LANDLORD'S CURING. If Tenant fails to perform any covenant within
any applicable cure period, then Landlord at its option may (without waiving any
right or remedy for Tenant's non-performance) at any time thereafter perform the
covenant for the account of Tenant. Tenant shall upon demand reimburse
Landlord's cost (including reasonable attorneys' fees) of so performing,
together with an administrative charge equal to 4% of such cost ("ADMINISTRATIVE
CHARGE") to be payable, after notice by Landlord, with the next installment of
Rent. Notwithstanding any other provision concerning cure periods, Landlord may
cure any non-performance for the account of Tenant after such notice to Tenant,
if any, as is reasonable under the circumstances if curing prior to the
expiration of the applicable cure period is reasonably necessary to prevent
likely damage to the Premises or possible injury to persons, or to protect
Landlord's interest in the Premises.

ARTICLE 15: SECURITY DEPOSIT.

15.01 SECURITY DEPOSIT. On the execution of this Lease, Tenant shall pay to
Landlord as a security deposit for the performance of the obligations of Tenant
hereunder any amount specified therefor in Article 1. Said security deposit may
be mingled with other funds of Landlord and no fiduciary relationship shall be
created with respect to such deposit. If Tenant shall fail to perform any of its
obligations under this Lease, Landlord may, but shall not be obliged to, apply
the security deposit to the extent necessary to cure the default, and Tenant
shall be obliged to reinstate such security deposit to the original amount
thereof upon demand. Within thirty (30) days after the expiration or sooner
termination of the Term the security deposit, to the extent not applied, shall
be returned to the Tenant with interest at a rate equal to the yield on 10-year
U.S. Treasury notes with a maturity date nearest the expiration date of the
Initial Term as reported in the Wall Street Journal or, if it ceases to be
published, a national financial publication reasonably selected by Landlord.

     In lieu of a cash security deposit pursuant to the immediately preceding
paragraph, on

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the execution on this Lease, Tenant may elect to deliver to Landlord as security
for the performance of the obligations of Tenant hereunder a letter of credit in
the initial amount specified therefor in Article 1 in accordance with the terms
set forth in this Section (as renewed, replaced, and/or reduced pursuant to this
Section, the "LETTER OF CREDIT"), such Letter of Credit to be in the form
attached hereto as Exhibit C, or such other form as is reasonably approved by
Landlord in accordance with the provisions of this paragraph. The Letter of
Credit (i) shall be irrevocable and shall be issued by a commercial bank
reasonably acceptable to Landlord that has an office in Boston or Cambridge,
Massachusetts, (ii) shall require only the presentation to the issuer of a
certificate of the holder of the Letter of Credit stating that Landlord is
entitled to draw upon the Letter of Credit pursuant to the terms of the Lease or
that a petition has been filed by Tenant (or any Transferee) for insolvency or
for appointment of a receiver, trustee or assignee or for adjudication,
reorganization or arrangement under any bankruptcy act and such petition filed
has not dismissed within thirty (30) days thereafter, (iii) shall be payable to
Landlord and its successors in interest as the Landlord and shall be freely
transferable without cost to any such successor or any lender holding a
collateral assignment of Landlord's interest in the Lease, (iv) shall be for an
initial term of not less than one year and contain a provision that such term
shall be automatically renewed for successive one-year periods unless the issuer
shall, at least forty-five (45) days prior to the scheduled expiration date,
give Landlord notice of such nonrenewable, and (v) shall otherwise be in form
and substance reasonably acceptable to Landlord. Notwithstanding the foregoing,
the term of the Letter of Credit for the final period of the Term shall be for a
term ending not earlier than the date sixty (60) days after the last day of the
Term.

     Landlord shall be entitled to draw upon the Letter of Credit for its full
amount (i) if Tenant shall be in default under the Lease, after the expiration
of any applicable notice or cure period (or if transmittal of a default notice
is barred by applicable law), or (ii) if, not less than thirty (30) days before
the scheduled expiration of the Letter of Credit, Tenant has not delivered to
Landlord a new Letter of Credit in accordance with this Section (which failure
shall be deemed a default without notice or cure period). Landlord may, but
shall not be obligated to, apply the amount so drawn to the extent necessary to
cure Tenant's default under the Lease. Any amount drawn in excess of the amount
applied by Landlord to cure any such default shall be held by Landlord as a
security deposit for the performance by Tenant of its obligations hereunder
pursuant to the terms set forth in the first paragraph of this Section 15.01.
After any such application by Landlord of the Letter of Credit, Tenant shall
reinstate the Letter of Credit to the amount originally required to be
maintained hereunder, upon demand. Within sixty (60) days after the expiration
or sooner termination of the Term the Letter of Credit, to the extent not
applied, shall be returned to the Tenant.

     In the event of a sale of the Building or lease, conveyance or transfer of
the Building, Landlord shall have the right to transfer the security to the
transferee, and upon notice to Tenant of such transfer, Landlord shall thereupon
be released by Tenant from all

                                     - 48 -
<Page>

liability for the return of such security; and subject to Section 10.02(b),
Tenant agrees to look to the transferee solely for the return of said security.
The provisions hereof shall apply to every transfer or assignment made of the
security to such a transferee. Tenant further covenants that it will not assign
or encumber or attempt to assign or encumber the Letter of Credit or the monies
deposited herein as security, and that neither Landlord nor its successors or
assigns shall be bound by any assignment, encumbrance, attempted assignment or
attempted encumbrance.

ARTICLE 16: PROTECTION OF LENDERS/GROUND LANDLORD

16.01 SUBORDINATION AND SUPERIORITY OF LEASE. Tenant agrees that this Lease and
the rights of Tenant hereunder will be subject and subordinate to any lien of
the holder of any existing or future mortgage, and to the rights of any lessor
under any ground or improvements lease of the Building (all mortgages and ground
or improvements leases of any priority are collectively referred to in this
Lease as "MORTGAGE," and the holder or lessor thereof from time to time as a
"MORTGAGEE"), and to all advances and interest thereunder and all modifications,
renewals, extensions and consolidations thereof. With respect to future liens of
any mortgage hereafter granted, Landlord will request that the mortgagee execute
and deliver to Tenant an agreement (in such form as such mortgagee may request)
in which the mortgagee agrees that such mortgagee shall not disturb Tenant in
its possession of the Premises upon Tenant's execution thereof and attornment to
such mortgagee as Landlord and performance of its Lease covenants (which
conditions Tenant agrees with all mortgagees to perform). Upon such attornment,
this Lease shall continue in full force and effect as a direct lease between the
mortgagee and Tenant upon all of the terms, conditions and covenants as are set
forth in this Lease, except that the mortgagee shall not be (i) liable in any
way to Tenant for any act or omission, neglect or default on the part of
Landlord under this Lease, (ii) responsible for any monies owing by or on
deposit with Landlord to the credit of Tenant, (iii) subject to any counterclaim
or setoff which theretofore accrued to Tenant against Landlord, (iv) bound by
any amendment or modification of this Lease subsequent to such mortgage, or by
any previous prepayment of Rent for more than one (1) month, which was not
approved in writing by the mortgagee, (v) liable beyond mortgagee's interest in
the Property, (vi) responsible for the performance of any work to be done by the
Landlord under this Lease to render the Premises ready for occupancy by the
Tenant, or (vii) required to remove any person occupying the Premises or any
part thereof, except if such person claims under the mortgagee. Tenant agrees
that any present or future mortgagee may at its option unilaterally elect to
subordinate, in whole or in part and by instrument in form and substance
satisfactory to such mortgagee alone, the lien of its mortgagee (or the priority
of its ground lease) to some or all provisions of this Lease.

     Tenant agrees that this Lease shall survive the merger of estates of ground
(or improvements) lessor and lessee. Until a mortgagee (either superior or
subordinate to this Lease) forecloses Landlord's equity of redemption (or
terminates or succeeds to a new

                                     - 49 -
<Page>

lease in the case of a ground or improvements lease) no mortgagee shall be
liable for failure to perform any of Landlord's obligations (and such mortgagee
shall thereafter be liable only after it succeeds to and holds Landlord's
interest and then only as limited herein). Tenant shall, if requested by
Landlord or any mortgagee, give notice of any alleged non-performance on the
part of Landlord to any such mortgagee provided that an address for such
mortgagee has been designated to Tenant, in writing, and Tenant agrees that such
mortgagee shall have a separate, consecutive reasonable cure period of no less
than thirty (30) days (to be reasonably extended in the same manner Landlord's
cure period is to be extended and for such additional periods as is necessary to
allow such Mortgagee to take possession of the Property) following Landlord's
cure period during which such mortgagee may, but need not, cure any
non-performance by Landlord. The agreements in this Lease with respect to the
rights and powers of a mortgagee constitute a continuing offer to any person
that may be accepted by taking a mortgage (or entering into a ground or
improvements lease) of the Premises. This Section shall be self-operative, but
in confirmation thereof, Tenant shall execute and deliver the subordination
agreement in such other form as such mortgagee may request.

16.02 RENT ASSIGNMENT. If from time to time Landlord assigns this Lease or the
rents payable hereunder to any person, whether such assignment is conditional in
nature or otherwise, such assignment shall not be deemed an assumption by the
assignee of any obligations of Landlord; but, subject to the limitations herein
including Sections 16.02 and 10.02(b), the assignee shall be responsible only
for non-performance of Landlord's obligations that occur after it succeeds to,
and only during the period it holds possession of, Landlord's interest in the
Premises after foreclosure or voluntary deed in lieu of foreclosure.

16.03 OTHER INSTRUMENTS. The provisions of this Article shall be self-operative;
nevertheless, Tenant agrees to execute, acknowledge and deliver any
subordination, attornment or priority agreements or other instruments conforming
to the provisions of this Lease (and being otherwise commercially reasonable)
from time to time requested by Landlord or any mortgagee, and further agrees
that its failure to do so within ten (10) days after written request shall be a
default for which this Lease may be terminated without further notice. Without
limitation, where Tenant in this Lease indemnifies or otherwise covenants for
the benefit of mortgagees, such agreements are for the benefit of mortgagees as
third party beneficiaries; and at the request of Landlord, Tenant from time to
time will confirm such matters directly with such mortgagee.

16.04 ESTOPPEL CERTIFICATES. Within fifteen (15) days after Landlord's request,
Tenant shall execute, acknowledge and deliver to Landlord a written statement
certifying: (i) that none of the terms or provisions of this Lease have been
changed (or if they have been changed, stating how); (ii) that this Lease has
not been canceled or terminated; (iii) the last date of payment of Base Rent and
other charges and the time period covered; (iv) that Landlord is not in default
under this Lease (or if Tenant states that Landlord is in default,

                                     - 50 -
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describing it in reasonable detail); and (v) such other information with respect
to Tenant or this Lease as Landlord may reasonably request or which any
prospective purchaser or encumbrancer of the Property may require. Landlord may
deliver any such statement by Tenant to any such prospective purchaser or
encumbrancer, which may rely conclusively upon such statement as true and
correct. If Tenant does not deliver such statement to Landlord within such
fifteen-(15)-day period, Landlord, and any such prospective purchaser or
encumbrancer, may conclusively presume and rely upon the following facts: (i)
that the terms and provisions of this Lease have not been changed except as
represented by Landlord; (ii) that this Lease has not been canceled or
terminated except as otherwise represented by Landlord; (iii) that not more than
one month's Base Rent or other charges have been paid in advance; and (iv) that
Landlord is not in default under this Lease. In such event, Tenant shall be
estopped from denying the truth of such facts.

16.05 FINANCIAL CONDITION. No more than once in any twelve (12) month period,
Tenant, within fifteen (15) days after request from Landlord from time to time,
shall deliver to Landlord Tenant's annual audited (or, if audited statements are
not then available, statements certified in writing by Tenant's chief financial
officer; provided that Tenant shall promptly provide Landlord with audited
statements for such period when they become available) financial statements for
the latest available two (2) fiscal years, including the year ending no more
than six (6) months prior to Landlord's request, and quarterly financial
statements certified in writing by Tenant's chief financial officer. Landlord
may request such financial statements more frequently in connection with a
specific sale or financing transaction. Landlord may deliver such financial
statements to its mortgagees and lenders and prospective mortgagees, lenders and
purchasers. Tenant represents and warrants to Landlord that each such financial
statement shall be true and accurate as of its date. Except for publicly
available information, financial statements shall be confidential and shall be
used only for the purposes set forth in this Section.

ARTICLE 17: MISCELLANEOUS PROVISIONS

17.01 LANDLORD'S CONSENT FEES. In addition to fees and expenses in connection
with Tenant Work, as described in Section 10.05, Tenant shall pay Landlord's
reasonable fees and expenses, including legal, engineering and other
consultants' fees and expenses, incurred in connection with Tenant's request for
Landlord's consent under Article 13 (Assignment and Subletting) or in connection
with any other act by Tenant that requires Landlord's consent or approval under
this Lease.

17.02 NOTICE OF LANDLORD'S DEFAULT. Tenant shall give notice of Landlord's
failure to perform any of its obligations under this Lease to Landlord, and to
any mortgagee or beneficiary under any deed of trust encumbering the Property
whose name and address have been given to Tenant. Landlord shall not be in
default under this Lease unless Landlord (or such mortgagee or beneficiary)
fails to cure such non-performance within thirty (30) days after receipt of
Tenant's notice. However, if such non-performance

                                     - 51 -
<Page>

requires more than thirty (30) days to cure, Landlord shall not be in default if
such cure is begun within such thirty (30) day period and diligently completed.
In no event shall Landlord be liable for indirect or consequential damages
(including loss of revenue, profits or data) arising out of any default by
Landlord under this Lease.

17.03 QUIET ENJOYMENT. Landlord agrees that, so long as (i) Tenant is not in
default under the terms of this Lease and (ii) this Lease is in full force and
effect, Tenant shall lawfully and quietly hold, occupy and enjoy the Premises
during the Term of this Lease without disturbance by Landlord or by any person
claiming through or under Landlord, subject to the terms of this Lease.

17.04 INTERPRETATION. In any provision relating to the conduct, acts or
omissions of Tenant, the term "TENANT" includes Tenant's agents, employees,
contractors, invitees, successors or others using the Premises with Tenant's
expressed or implied permission.

17.05 NOTICES. All notices, requests and other communications required under
this Lease shall be in writing, addressed as specified in Article 1, and shall
be (i) personally delivered, (ii) sent by certified mail, return receipt
requested, postage prepaid, (iii) delivered by a national overnight delivery
service that maintains delivery records or (iv) sent by telecopier or facsimile
machine ("fax") that automatically generates a transmission report, with a copy
also sent as described in clause (i), (ii) or (iii). All notices shall be
effective upon delivery (or refusal to accept delivery); provided, however, that
notice by fax or telecopy shall be effective when transmitted. Either party may
change its notice address upon written notice to the other party.

17.06 NO RECORDATION. Tenant shall not record this Lease. Either Landlord or
Tenant may require that a statutory notice, short form or memorandum of this
Lease executed by both parties be recorded. Tenant may record any SNDA
(notifying Landlord of the date and book and page number) or request Landlord to
record it on Tenant's behalf. The party requesting or requiring such recording
shall pay all expenses, transfer taxes and recording fees.

17.07 CORPORATE AUTHORITY. If Tenant is a business entity, then the person or
persons executing this Lease on behalf of Tenant jointly and severally warrant
and represent in their individual capacities that (a) Tenant is duly organized,
validly existing and in good standing under the laws of the jurisdiction in
which such entity was organized; (b) Tenant has the authority to own its
property and to carry on its business as contemplated under this Lease; (c)
Tenant is in compliance with all laws and orders of public authorities
applicable to Tenant; (d) Tenant has duly executed and delivered this Lease; (e)
the execution, delivery and performance by Tenant of this Lease (i) are within
the powers of Tenant, (ii) have been duly authorized by all requisite action,
(iii) will not violate any provision of law or any order of any court or agency
of government, or any agreement or other instrument to which Tenant is a party
or by which it or any of its property is bound, and

                                     - 52 -
<Page>

(iv) will not result in the imposition of any lien or charge on any of Tenant
Property, except by the provisions of this Lease; and (f) the Lease is a valid
and binding obligation of Tenant in accordance with its terms. Tenant, if a
business entity, agrees that breach of the foregoing warranty and representation
shall at Landlord's election be a default under this Lease for which there shall
be no cure. This warranty and representation shall survive the termination of
the Term.

17.08 JOINT AND SEVERAL LIABILITY, COUNTERPARTS. If more than one party signs
this Lease as Tenant, they shall be jointly and severally liable for all
obligations of Tenant. This Lease may be executed in multiple counterparts, each
of which shall be deemed an original and all of which together shall constitute
a single agreement.

17.09 FORCE MAJEURE. If a party cannot perform any of its obligations due to
events beyond its reasonable control (other than the inability to make payments
when due), the time provided for performing such obligations shall be extended
by a period of time equal to the duration of the events. Events beyond a party's
reasonable control include acts of God, war, civil commotion, labor disputes,
strikes, fire, flood or other casualty, shortages of or the inability to obtain
labor or material from customary sources on customary terms, government
regulation or restriction, weather conditions or acts, neglects or delays of the
other party.

17.10 LIMITATION OF WARRANTIES. Landlord and Tenant expressly agree that there
are and shall be no implied warranties of merchantability, habitability,
suitability, fitness for a particular purpose or of any other kind arising out
of this Lease, and there are no warranties which extend beyond those expressly
set forth in this Lease.

17.11 NO OTHER BROKERS. Landlord and Tenant represent and warrant to each other
that the brokers named in Article 1 are the only agents, Broker(s), finders or
other parties with whom such party has dealt who may be entitled to any
commission or fee with respect to this Lease or the Premises or the Property.
Landlord and Tenant agree to indemnify and hold the other harmless from any
claim, demand, cost or liability, including attorneys' fees and expenses,
asserted by any party other than the brokers named in Article 1 based upon
dealings of that party with the indemnifying party. The provisions of this
Section shall survive the Term or early termination of this Lease.

17.12 APPLICABLE LAW AND CONSTRUCTION. This Lease may be executed in
counterparts, shall be construed as a sealed instrument, and shall be governed
exclusively by the provisions hereof and by the laws of the state where the
Property is located without regard to principles of choice of law or conflicts
of law. A facsimile signature to this Lease shall be sufficient to prove the
execution by a party. The covenants of Landlord and Tenant are independent, and
such covenants shall be construed as such in accordance with the laws of The
Commonwealth of Massachusetts. If any provisions shall to any extent be invalid,
the remainder shall not be affected. Other than contemporaneous instruments
executed and

                                     - 53 -
<Page>

delivered of even date (i.e. the notice of lease, if any, pursuant to Section
17.06 and the Initial Warrant), this Lease contains all of the agreements
between Landlord and Tenant relating in any way to the Premises and supersedes
all prior agreements and dealings between them. There are no oral agreements
between Landlord and Tenant relating to this Lease or the Premises. This Lease
may be amended only by instrument in writing executed and delivered by both
Landlord and Tenant. The provisions of this Lease shall bind Landlord and Tenant
and their respective successors and assigns, and shall inure to the benefit of
Landlord and its successors and assigns and of Tenant and its permitted
successors and assigns, subject to Article 13. As used herein, "NON-MONETARY
DEFAULT" shall mean a default that cannot be substantially cured by the payment
of money. The titles are for convenience only and shall not be considered a part
of the Lease. This Lease shall not be construed more strictly against one party
than against the other merely by virtue of the fact that it may have been
prepared primarily by counsel for one of the parties, it being recognized that
both Landlord and Tenant have contributed substantially and materially to the
preparation of this Lease. If Tenant is granted any extension or other option,
to be effective the exercise (and notice thereof) shall be unconditional; and if
Tenant purports to condition the exercise of any option or to vary its terms in
any manner, then the option granted shall be void and the purported exercise
shall be ineffective. The enumeration of specific examples of a general
provisions shall not be construed as a limitation of the general provision.
Unless a party's approval or consent is required by the express terms of this
Lease not to be unreasonably withheld, such approval or consent may be withheld
in the party's sole discretion. The submission of a form of this Lease or any
summary of its terms shall not constitute an offer by Landlord to Tenant; but a
leasehold shall only be created and the parties bound when this Lease is
executed and delivered by both Landlord and Tenant and approved by the holder of
any mortgagee of the Premises having the right to approve this Lease. Nothing
herein shall be construed as creating the relationship between Landlord and
Tenant of principal and agent, or of partners or joint venturers or any
relationship other than landlord and tenant. This Lease and all consents,
notices, approvals and all other related documents may be reproduced by any
party by any electronic means or by facsimile, photographic, microfilm,
microfiche or other reproduction process and the originals may be destroyed; and
each party agrees that any reproductions shall be as admissible in evidence in
any judicial or administrative proceeding as the original itself (whether or not
the original is in existence and whether or not reproduction was made in the
regular course of business), and that any further reproduction of such
reproduction shall likewise be admissible. If any payment in the nature of
interest provided for in this Lease shall exceed the maximum interest permitted
under controlling law, as established by final judgment of a court, then such
interest shall instead be at the maximum permitted interest rate as established
by such judgment. The term "TERM" includes the Initial Term as it may be
extended pursuant to Section 3.03.

ARTICLE 18: EXPANSION RIGHTS

18.1 RIGHT OF FIRST OFFER. Reference is made to certain space outlined as the
First Offer

                                     - 54 -
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Space on EXHIBIT N (the "First Offer Space"). Before entering into a lease for
at least 5,000 rentable square feet of the First Offer Space with a third party
for office, laboratory, and/or research and development uses (but excluding from
Tenant's first offer right leases entered into during the initial lease-up of
the First Offer Space, and renewals, extensions, and expansions of the same, and
any lease for retail or other uses), Landlord shall notify Tenant of the terms
on which Landlord intends to lease the space ("Landlord's Notice"). Within five
business days after receipt of Landlord's Notice, Tenant may, by written notice
delivered to Landlord, (i) reject Landlord's Notice, or (ii) reject Landlord's
Notice but unconditionally and irrevocably offer to lease such space from
Landlord for its own use on specific economic terms proposed in Tenant's
response, or (iii) unconditionally and irrevocably offer to lease such space
from Landlord for its own use on the terms set forth in Landlord's Notice (the
failure by Tenant to timely respond as aforesaid being deemed Tenant's rejection
of Landlord's Notice).

     If Landlord's Notice is rejected under clause (i) above (or deemed rejected
by Tenant's failure to timely respond), then Landlord may enter into any lease
for such space, provided that Landlord shall deliver to Tenant a new Landlord's
Notice prior to entering into an initial lease for the First Offer Space
providing for an effective rent (after taking into account any free rent or
other concessions) more than ten percent (10%) less than that specified in
Landlord's Notice.

     If Tenant timely offers to lease the space on alternative terms as set
forth in clause (ii) above, then Landlord may, by written notice delivered
within thirty days of receipt thereof, accept or decline such offer (the failure
to so respond being deemed Landlord's election to decline Tenant's offer). If
such offer under clause (ii) is declined (or deemed declined), then, for a
period of one year after Landlord's receipt of Tenant's offer, Landlord may
enter into any lease for such space at an effective rent (after taking into
account any tenant improvement allowance) greater than that set forth in
Tenant's offer. If, during such one-year period, Landlord desires to enter into
a third-party lease at an effective rent less than or equal to the effective
rent set forth in Tenant's offer, Landlord shall deliver to Tenant a new
Landlord's Notice. If Landlord does not enter into any lease within such
one-year period, Landlord shall re-commence the process under this Section
before entering into a lease for the space.

     If Tenant timely offers to lease the space as set forth in clause (iii)
above, then Landlord shall, by written notice delivered within thirty days of
receipt thereof, accept such offer (the failure to so respond being deemed
Landlord's election to accept the proposed lease).

     If Landlord timely accepts an offer by Tenant under this Section, the space
shall, subject to the following paragraph below and without further action by
the parties, be leased by Tenant on the accepted terms and otherwise on all of
the terms of the Lease in effect immediately prior to such expansion, provided
that, at the request of either party,

                                     - 55 -
<Page>

Landlord and Tenant shall promptly execute and deliver an agreement confirming
such expansion of the Premises and the estimated date the Premises are to be
expanded pursuant to this Paragraph with a provision for establishing the
effective date of such expansion based on actual delivery. Landlord's failure to
deliver, or delay in delivering, all or any part of the First Offer Space, for
any reason, shall not give rise to any liability of Landlord, shall not alter
Tenant's obligation to accept such space when delivered, shall not constitute a
default of Landlord, and shall not affect the validity of the Lease.

     Notwithstanding any provision of this Section to the contrary, Tenant's
rights under this Section shall be void, at Landlord's election, if (i) Tenant
is in default hereunder, after any applicable notice and cure periods have
expired, at any time prior to the time Tenant makes any election with respect to
the First Offer Space under this Section or at the time the First Offer Space
would be added to the Premises, (ii) any sublease of greater than twenty five
percent (25%) of the Premises in the aggregate exists at any such time which
requires Landlord's consent under Article 13, or (iii) Tenant has exercised its
termination rights pursuant to Section 3.04 and/or 13.07 of this Lease. Nothing
in this Section shall be construed to grant to Tenant any rights or interest in
any space in the Building, and any claims by Tenant alleging a failure of
Landlord to comply herewith shall be limited to claims for monetary damages.
Tenant may not assert any rights in any space nor file any lis pendens or
similar notice with respect thereto.

      [Remainder of Page Intentionally Left Blank, Signature Page Follows]

                                     - 56 -
<Page>

                                  LANDLORD:

                                  21 ERIE REALTY TRUST

                                  By: /s/ David M. Roby
                                      -----------------
                                          Name: DAVID M. ROBY
                                          Title: Trustee

                                  TENANT:

                                  METABOLIX, INC.

                                  By: /s/ James J. Barber
                                      -------------------
                                      Name: JAMES J. BARBER
                                      Title: President or Vice President

                                  By: /s/ J. Barber
                                      -------------------
                                      Name: J. BARBER
                                      Title: Treasurer or Assistant Treasurer

                                     - 57 -
<Page>

                                    EXHIBIT A

                                    PROPERTY

PARCEL I

     A certain parcel of land with the buildings thereon situated in Cambridge,
Middlesex County, Massachusetts and being shown as Lot "A" on a Plan entitled
"Subdivision of Land in Cambridge dated September 20, 1961, drawn by Edward
Smith, Surveyor, 517 School Street, Belmont," recorded with Middlesex South
District Registry of Deeds, Book 9910, Page 526, and bounded and described as
follows:

NORTHEASTERLY        by Merriam Street, Eighty-five and sixty-six one
                     hundredths (85.66) feet;

SOUTHEASTERLY        by Waverly Street, Two hundred (200.00) feet;

SOUTHWESTERLY        by Erie Street, One hundred twenty-five (125.00) feet;

NORTHWESTERLY        by land of owners unknown One hundred two and fourteen one
                     hundredths (102.14) feet;

NORTHEASTERLY        by Lot "B" as shown on said plan by line running through
                     the center of a twelve (12) inch brick partition wall,
                     Thirty-eight and thirteen one hundredths (38.13) feet; and

NORTHWESTERLY        by Lot "B" by a line running through the center of a twelve
                     (12) inch brick partition wall, Ninety-seven and eighty-six
                     one hundredths (97.86) feet.

     Containing Twenty-one thousand, two hundred and eight (21,208) square feet
of land, be all or any of said measurements and contents, more or less, and
subject to easements of record insofar as they may now be in force and
applicable, and subject to the provisions of a Party Wall Agreement dated
October 5, 1961, and recorded October 16, 1961, with Middlesex South District
Registry of Deeds, Book 9910, Page 528.

PARCEL II

     Beginning at a point in the southwesterly line of Merriam Street, said
point being distant eighty-five and sixty-six one hundredths (85.66) feet from
the intersection of the southwesterly line of Merriam Street and the
northwesterly line of Waverly Street;

     Thence running in a southwesterly direction partly through the center of a
12" brick

                                     - 58 -
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partition wall ninety-seven and eighty-six one hundredths (97.86) feet to a
point;

     Thence running in a northwesterly direction through the center of a 12"
brick partition wall thirty-eight and thirteen one hundredths (38.13) feet to a
point;

     Thence running in a southwesterly direction two and fourteen one hundredths
(2.14) feet to a point;

     Thence running in a northwesterly direction fifteen and sixty-one
hundredths (15.61) feet;

     Thence turning and running in a northeasterly direction one hundred
(100.00) feet to a point in the southwesterly line of Merriam Street;

     Thence running in a southeasterly direction along with the southwesterly
line of Merriam Street fifty-three and seventy-four one hundredths (53.74) feet
to the point of beginning.

     The above described parcel of land, containing five thousand two hundred
and ninety-two (5,292) square feet, is shown as Lot "B" on a Plan entitled
"Subdivision of Land in Cambridge dated September 20, 1961, drawn by Edward
Smith Surveyor, 517 School St. Belmont," recorded with Middlesex South District
Registry of Deeds, Cambridge, Massachusetts at Book 9910, Page 526.

     Including, also, any interests in fee to any portion of Merriam Street, a
private way, which runs with the aforedescribed parcels.

                                     - 59 -
<Page>

                                    EXHIBIT B

                                    PREMISES

                                     - 60 -
<Page>

                                    EXHIBIT B
                                   FIRST FLOOR
                             CROSS-MATCHED AREAS ARE
                              INCLUDED IN PREMISES

                         [Floor plan for the first floor.]

<Page>

                                    EXHIBIT B
                                  SECOND FLOOR
                             CROSS-MATCHED AREAS ARE
                             EXCLUDED FROM PREMISES

                        [Floor plan for the second floor.]

<Page>

                                    EXHIBIT C

                            FORM OF LETTER OF CREDIT

                            FORM OF LETTER OF CREDIT

[Issuer]
[Street Address]
Date:       , 2003

                    IRREVOCABLE STANDBY LETTER OF CREDIT NO.

Account Party:

In favor of Beneficiary:21 Erie Realty Trust, its successors and assigns
                     c/o Lyme Properties, LLC
                     101 Main Street, 18th Floor
                     Cambridge, MA 02142

    AMOUNT                                          EXPIRY DATE:
USD $                                                   [Expiry Date]
[Dollar Amount]

Gentlemen:

We hereby open our irrevocable letter of credit in your favor for an amount of
USD      $(                      U.S. Dollars Only U.S. Dollars Only) available
by your draft at sight drawn on the [Lending Institution Name, Lending
Institution Address], bearing the clause "Drawn under [Issuer] Letter of Credit
No.         dated            , 2003," and accompanied by the following document:

     Beneficiary's signed statement stating that:

     (A)   "The undersigned Beneficiary is entitled to draw upon this Letter of
           Credit pursuant to the terms of that Lease dated [Lease Date] for
           premises at 21 Erie Street, Cambridge, Massachusetts between
           and 21 Erie Realty Trust for the amount drawn hereunder. 21 Erie
           Realty Trust hereby makes demand for the payment of $
           of the Letter of Credit." Such statement shall be conclusive as to
           such matters.

                                       OR

     (B)   "The undersigned Beneficiary is entitled to draw upon this Letter of
           Credit

                                     - 61 -
<Page>

           because a petition has been filed with respect to the tenant under
           that certain Lease dated [Lease Date] for premises at 21 Erie Street,
           Cambridge, Massachusetts between     and 21 Erie Realty Trust for (x)
           insolvency or for appointment of a receiver, trustee or assignee, or
           (y) for adjudication, reorganization or arrangement under any
           bankruptcy act, and such petition filed was not dismissed within
           thirty (30) days thereafter." Such statement shall be conclusive as
           to such matters.

Partial draws hereunder are permitted. This Letter of Credit is transferable
without charge by Beneficiary. This Letter of Credit sets forth in full the
terms of our undertaking and such undertaking shall not in any way be modified,
amended, or amplified by reference to any document(s), instrument(s),
contract(s), or agreement(s) referred to herein or in which this Letter of
Credit relates, and any such reference shall not be deemed to incorporate herein
by reference any document(s), instrument(s), contract(s), or agreement(s).

It is a condition of this Letter of Credit that it shall be deemed automatically
extended without amendment for one year from the present or any future
expiration date of this Letter of Credit unless at least sixty (60) days prior
to the then current expiration date we notify the Beneficiary by registered
letter, at the above address (or such other address of which you notify us in
writing), that we elect not to consider this Letter of Credit renewed for such
additional period. If such notice is given, then during such notice period
(i.e., at least sixty (60) day period commencing on the date of such notice and
ending with the then applicable expiry date of this Letter of Credit), this
Letter of Credit shall remain in full force and effect and Beneficiary may draw
up to the full amount of the sum when accompanied by your draft drawn on us at
sight as described above in the first paragraph of this Letter of Credit.

If required by any mortgagee of the property on which the premises subject to
the above described lease is located, we shall acknowledge the assignment of
this Letter of Credit (and/or the proceeds of this Letter of Credit) to such
mortgagee at no charge.

We hereby engage with you that drafts drawn and presented in compliance with the
terms of this credit will be immediately honored by us if presented at any of
our offices or by facsimile transmission at                        on or before
[Expiry Date], as such date may be extended pursuant to the terms hereof.

This Letter of Credit is subject to The Uniform Customs and Practice for
Documentary Credits (1993 Revision), International Chamber of Commerce
Publication No. 500, which is incorporated by reference herein.

Very truly yours,

-----------------------------
Authorized Signature

                                     - 62 -
<Page>

                                    EXHIBIT D

                             FORM OF CONFIRMATION OF
                                  DELIVERY DATE

     Reference is made to the Lease dated                  between
, as landlord, and                    , as tenant (the "LEASE"). The terms
listed below are used as defined in the Lease.

     Landlord and Tenant confirm the following:

           Term Commencement Date:
                                  -------------------------

           Delivery Date:
                         ----------------------------------

           Rent Commencement Date:
                                  -------------------------

           Expiration of Initial Term:
                                      ---------------------

           Tenant's fax number for purposes of notice:
                                                      -----

                                        LANDLORD:

                                        By:
                                           ----------------------------
                                           Name:
                                                -----------------------
                                           Title:
                                                 ----------------------

                                        TENANT:

                                        By:
                                           ----------------------------
                                           Name:
                                                -----------------------
                                           Title:
                                                 ----------------------

                                     - 63 -
<Page>

                                    EXHIBIT E

                              RULES AND REGULATIONS

1.     The common entrances, lobbies, elevators, sidewalks, and stairways of the
       Building and the Property shall not be encumbered or obstructed by
       Tenant, Tenant's agents, servants, employees, licensees or visitors or
       used by them for any purposes other than ingress or egress to and from
       the Building.

2.     Landlord reserves the right to have Landlord's structural engineer review
       Tenant's floor loads on the Building at Tenant's expense.

3.     Tenant, or the employees, agents, servants, visitors or licensees of
       Tenant shall not at any time place, leave or discard any rubbish, paper,
       articles, or objects of any kind whatsoever outside of the Building.
       Bicycles shall not be permitted in the Building unless Landlord provides
       for the parking thereof in the Building.

4.     Tenant shall not place objects against glass partitions or doors or
       windows or adjacent to any common space which would be unsightly from the
       exterior of the Building and will promptly remove the same upon notice
       from Landlord.

5.     Tenant shall not make noises, cause disturbances, create vibrations,
       odors or noxious fumes or use or operate any electric or electrical
       devices or other devices that emit sound waves or that would interfere
       with the operation of any device or equipment or radio or television
       broadcasting or reception from or within the Building or elsewhere, or
       with the operation of roads or highways in the vicinity of the Building
       and shall not place or install any projections, antennae, aerials, or
       similar devices inside or outside of the Building, without the prior
       written approval of Landlord.

6.     Tenant shall not: (a) use the Building for lodging, or for any immoral or
       illegal purposes; (b) use the Building to engage in the manufacture or
       sale of spirituous, fermented, intoxicating or alcoholic beverages in the
       Building; (c) use the Building to engage in the manufacture or sale of,
       or permit the use of, any illegal drugs on the Building.

7.     No awning or other projections shall be attached to the outside walls or
       windows. No curtains, blinds, shades, screens or signs, other than those,
       if any, furnished by Landlord, shall be attached to, hung in, or used in
       connection with any exterior window or door of the Building without the
       prior written consent of Landlord. No sign, advertisement, object, notice
       or other lettering shall be exhibited, inscribed, painted or affixed on
       any part of the outside or inside of the Building if visible from

                                     - 64 -
<Page>

       outside of the Building without the prior written consent of Landlord.

8.     Door keys, pass cards or similar devices for doors in the Building will
       be furnished on the Commencement Date by Landlord. If Tenant shall affix
       additional locks on doors then Tenant shall furnish Landlord with copies
       of keys or pass cards or similar devices for said locks.

9.     Tenant shall cooperate and participate in all reasonable security
       programs affecting the Building and Property.

10.    Tenant assumes full responsibility for protecting its space from theft,
       robbery and pilferage, which includes keeping doors locked and other
       means of entry to its space in the Building closed and secured.

11.    The water and wash closets and other plumbing fixtures shall not be used
       for any purposes other than those for which they were constructed, and no
       sweepings, rubbish, rags, or other substances shall be thrown therein.

12.    Discharge of industrial sewage shall only be permitted if Tenant, at its
       sole expense, shall have obtained and delivered to Landlord all necessary
       permits and licenses therefor, including without limitation permits from
       state and local authorities having jurisdiction thereof.

13.    The use of asbestos containing cement or other similar asbestos
       containing adhesive material is expressly prohibited.

14.    In the event of any conflict between the provisions of this EXHIBIT E and
       the provisions of the Lease, the provisions of the Lease shall govern.

                                     - 65 -
<Page>

                                    EXHIBIT F

                            ENVIRONMENTAL SUBSTANCES

1.     Usual and customary office and cleaning supplies, in quantities normally
       maintained in offices of the same size and nature as the Premises.

2.     Usual and customary office equipment (including copiers and printers).

3.     Tenant shall not place, install or operate on the Premises or in any
       other part of the Building or on the grounds any engine or machinery, or
       maintain, use or keep any flammable, explosive or hazardous material
       without the prior written consent of Landlord.

4.     Tenant shall not use, keep or permit to be used or kept any foul or
       noxious gas or substance on, in or around the Premises unless approved by
       Landlord. Tenant shall not use, keep or permit to be used or kept any
       flammable or combustible materials without proper governmental permits
       and approvals.

5.     The following equipment (see attached):

                                     - 66 -
<Page>

                     BASEMENT SOLVENT INVENTORY NOV 26, 2003

METABOLIX DECLARATION OF TOXIC AND FLAMMABLE SUBSTANCES TO BE USED

Date:             December 24th, 2003
Prepared by:      H.J. van Walsem, VP Manufacturing, Development and Operations

WASTE AND SOLVENT ROOM (FIRST FLOOR)

<Table>
<Caption>
   QUANTITY       PACKAGING                   CHEMICAL                   TOTAL QUANTITY (GAL)
   --------       ---------                   --------                   --------------------
   <S>           <C>            <C>                                               <C>
      2          55 gal drum        Non-Chlorinated Waste Solvent                 110
      2          56 gal drum          Chlorinated Waste Solvent                   110
      1          55 gal drum     Solids waste, solvent contaminated                5
     10          5 gal drums    Various solvents (2nd floor overflow)             50
   SUBTOTAL                                                                       275
</Table>

pH ADJUSTMENT TANK AREA (FIRST FLOOR)

<Table>
<Caption>
   QUANTITY       PACKAGING                   CHEMICAL                   TOTAL QUANTITY (GAL)
   --------       ---------                   --------                   --------------------
      <S>        <C>                 <C>                                 <C>
      3          20 gal drum               Sulphuric acid, 98%                    60
      3          20 gal drum                Caustic Soda, 50%                     60
                                                                           500 gal/day max;
1000 liter/day                       Aqueous Waste Water to Sewer        150 gal/day average
</Table>

SOLVENT STORAGE ROOM (SECOND FLOOR)

<Table>
<Caption>
   QUANTITY       PACKAGING                   CHEMICAL                   TOTAL QUANTITY (GAL)
   --------       ---------                   --------                   --------------------
   <S>           <C>                   <C>                                        <C>
     10          5 gal drum                1,4 Butanediol                         25
     10          5 gal drum                Caprylic Acid                          25
     10          5 gal drum                 Caproic Acid                          25
     10          5 gal drum                   Corn Oil                            25
     4           5 gal drum                Ethyl Alcohol                          20
     5           5 gal drum                   Heptane                             25
     5           5 gal drum                    Hexane                             25
     5           5 gal drum            Methyl Isobutyl Ketone                     25
     5           5 gal drum                Cyclohexanone                          25
     5             4 liter                    Acetone                             5
     5             4 liter                 Butyl Acetate                          5
     5             4 liter                 Ethyl Acetate                          5
     10            4 liter                   Chloroform                           10
     4             4 liter                Dichloromethane                         4
   SUBTOTAL                                                                       249
</Table>

SOLVENT CABINETS FOR SPECIALTY SOLVENTS (SECOND FLOOR)

<Table>
<Caption>
   QUANTITY       PACKAGING                   CHEMICAL                   TOTAL QUANTITY (GAL)
   --------       ---------                   --------                   --------------------
      <S>          <C>                <C>                                         <C>
      3            4 liter                   1,4 Dioxane                          3
      2            2 liter            1-Methyl, 2-Pyrrolidinone                   1
      2            2 liter                2-Methoxyethanol                        1
      2            4 liter             Methyl Isobutyl Ketone                     2
      1            4 liter                  Acetonitrile                          1
</Table>

<Page>

                     BASEMENT SOLVENT INVENTORY NOV 26, 2003

AT 21 ERIE (AS REQUIRED FOR LEASE)

                                   DESIGNATION
Flammable solvents
Non-flammable but toxic
Flammable solvents absorbed onto solids materials
Flammable solvents

                                   DESIGNATION
Corrosive but not flammable
Corrosive but not flammable
As per permit to be finalized; typically pH of 5.5-
10.0

                                   DESIGNATION
Combustible but not flammable
Combustible but not flammable
Combustible but not flammable
Combustible but not flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Non-flammable but toxic
Non-flammable but toxic

                                   DESIGNATION
Flammable
Flammable
Flammable
Flammable
Flammable

<Page>

                     BASEMENT SOLVENT INVENTORY NOV 26, 2003
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable
Flammable

                                   DESIGNATION
Corrosive Liquid
Corrosive Liquid
Corrosive Liquid
Corrosive Liquid
Corrosive Liquid
Volatile Base (stored in cold storage)
Organic corrosive, pungent

tory.

                                   DESIGNATION
Toxic
Mutagen
Mutagen
Toxic
Toxic in controlled cabinet
Biological inhibitors

                                   DESIGNATION

Biosafety Level 1 microbial strains. Controlled by IBC, all waste
deactivated before discharge. Biosafety Level 1 strains handled
according to GLP. No pathogens are handled on site.

<Page>

                                    EXHIBIT G

                       CONSTRUCTION DOCUMENT REQUIREMENTS

     (a)       PREPARATION OF CONSTRUCTION DOCUMENTS. The Construction
Documents shall include all architectural, mechanical, electrical and structural
drawings and detailed specifications for the Tenant Work and shall show all work
necessary to complete the Tenant Work including all cutting, fitting, and
patching and all connections to the mechanical and electrical systems and
components of the Building. Tenants leasing partial floors shall design
entrances, doors and any other elements which visually integrate with the
elevator lobbies and common areas in a manner and with materials and finishes
which are compatible with the common area finishes for such floor. Landlord
reserves the right to reject Construction Documents which in its reasonable
opinion fail to comply with this provision. The Construction Documents shall
include:

          (i)  MAJOR WORK INFORMATION: A list of any items or matters which
          might require structural modifications to the Building, including the
          following:

               (1)  Location and details of special floor areas exceeding 150
                    pounds of live load per square foot;
               (2)  Location and weights of storage files, batteries, HVAC units
                    and technical areas;
               (3)  Location of any special soundproofing requirements;
               (4)  Existence of any extraordinary HVAC requirements
                    necessitating perforation of structural members; and
               (5)  Existence of any requirements for heavy loads, dunnage or
                    other items affecting the structure.

          (ii) PLANS SUBMISSION: Two (2) blackline drawings and one (1) CAD disk
          showing all architectural, mechanical and electrical systems,
          including cutsheets, specifications and the following:

          CONSTRUCTION PLANS:

               (1)  All partitions shall be shown; indicate ratings of all
                    partitions; indicate all non-standard construction and
                    details referenced;
               (2)  Dimensions for partition shall be shown to face of stud;
                    critical tolerances and +/- dimensions shall be clearly
                    noted;

                                     - 67 -
<Page>

               (3)  All doors shall be shown on and shall be numbered and
                    scheduled on door schedule; indicate ratings of all doors;

               (4)  All non-standard construction, non-standard materials and/or
                    installation shall be explicitly noted; equipment and
                    finishes shall be shown and details referenced; and

               (5)  All plumbing fixtures or other equipment requirements and
                    any equipment requiring connection to Building plumbing
                    systems shall be noted.

          REFLECTED CEILING PLAN:

               (1)  Layout suspended ceiling grid pattern in each room,
                    describing the intent of the ceiling working point, origin
                    and/or centering; and

               (2)  Locate all ceiling-mounted lighting fixtures and air
                    handling devices including air dampers, fan boxes, etc.,
                    lighting fixtures, supply air diffusers, wall switches, down
                    lights, special lighting fixtures, special return air
                    registers, special supply air diffusers, and special wall
                    switches.

          TELECOMMUNICATIONS AND ELECTRICAL EQUIPMENT PLAN:

               (1)  All telephone outlets required;

               (2)  All electrical outlets required; note non-standard power
                    devices and/or related equipment;

               (3)  All electrical requirements associated with plumbing
                    fixtures or equipment; append product data for all equipment
                    requiring special power, temperature control or plumbing
                    considerations;

               (4)  Location of telecommunications equipment and conduits; and

               (5)  Components and design of Tenant's Equipment (including
                    associated equipment) as installed, in sufficient detail to
                    evaluate weight, bearing requirements, wind-load
                    characteristics, power requirements and the effects on
                    Building structure, moisture resistance of the roof membrane

                                     - 68 -
<Page>

                    and operations of pre-existing telecommunications equipment.

          DOOR SCHEDULE:

               (1)  Provide a schedule of doors, sizes, finishes, hardware sets
                    and ratings; and

               (2)  Non-standard materials and/or installation shall be
                    explicitly noted.

          HVAC:

               (1)  Areas requiring special temperature and/or humidity control
                    requirements;

               (2)  Heat emission of equipment (including catalogue cuts), such
                    as CRTs, copy machines, etc.;

               (3)  Special exhaust requirements - conference rooms, pantry,
                    toilets, etc.; and

               (4)  Any extension of system beyond demised space.

          ELECTRICAL:

               (1)  Special lighting requirements;

               (2)  Power requirements and special outlet requirements of
                    equipment;

               (3)  Security requirements;

               (4)  Supplied telephone equipment and the necessary space
                    allocation for same; and

     (5)  Any extensions of tenant equipment beyond demised space.

          PLUMBING:

               (1)  Remote toilets;

               (2)  Pantry equipment requirements;

                                     - 69 -
<Page>

               (3)  Remote water and/or drain requirements such as for sinks,
                    ice makers, etc.; and

               (4)  Special drainage requirements, such as those requiring
                    holding or dilution tanks.

          ROOF:

               Detailed plan of any existing and proposed roof equipment showing
               location and elevations of all equipment and all new penetrations
               through the roof including, but not limited to, plumbing,
               mechanical, and electrical services.

          SITE:

               Detailed plan, including fencing, pads, conduits, landscaping and
               elevations of equipment.

          SPECIAL SERVICES:

               Equipment cuts, power requirements, heat emissions, raised floor
               requirements, fire protection requirements, security
               requirements, and emergency power.

     (b)  PLAN REQUIREMENTS. The Construction Documents shall be fully detailed
and fully coordinated with each other and with existing field conditions, shall
show complete dimensions, and shall have designated thereon all points of
location and other matters, including special construction details and finish
schedules. All drawings shall be uniform size and shall incorporate the standard
electrical and plumbing symbols and be at a scale of 1/8" = 1'0" or larger.
Materials and/or installation shall be explicitly noted and adequately specified
to allow for Landlord review, building permit application, and construction. All
equipment and installations shall be made in accordance with standard materials
and procedures unless a deviation outside of industry standards is shown on the
Construction Documents and approved by Landlord. To the extent practicable, a
concise description of products, acceptable substitutes, and installation
procedures and standards shall be provided. Product cuts must be provided and
special mechanical or electrical loads noted. Landlord's approval of the plans,
drawings, specifications or other submissions in respect of any work, addition,
alteration or improvement to be undertaken by or on behalf of Tenant shall
create no liability or responsibility on the part of Landlord for their
completeness, design sufficiency or compliance with requirements of any
applicable laws, rules or regulations of any governmental or quasi-governmental
agency, board or authority.

                                     - 70 -
<Page>

     (c)  DRAWING AND DOCUMENT PRODUCTION. Landlord shall provide Tenant with
two (2) blackline drawings and one (1) CAD disk showing the Building and site
outline, core walls and columns, together with corridor and demising wall
location plans.

     (d)  CHANGE ORDERS. The Construction Documents shall not be materially
changed or modified by Tenant after approval by Landlord without the further
approval in writing by Landlord, which approval shall not be unreasonably
withheld or delayed. Landlord shall not be obligated to approve any change or
modification of the Construction Documents which in Landlord's sole opinion
shall cause any additional cost or expense to Landlord for which Tenant has not
agreed to reimburse Landlord.

                                     - 71 -
<Page>

                                    EXHIBIT H

                         TENANT WORK INSURANCE SCHEDULE

     TENANT'S LIABILITY INSURANCE

     Tenant shall be responsible for requiring all Tenant Contractors doing
construction or renovation work to purchase and maintain such insurance as shall
protect it from the claims set forth below which may arise out of or result from
any Tenant Work whether such Tenant Work is completed by Tenant or by any Tenant
Contractor or by any person directly or indirectly employed by Tenant or any
Tenant Contractor, or by any person for whose acts Tenant or any Tenant
Contractor may be liable:

     1.   Claims under workers' compensation, disability benefit and other
          similar employee benefit acts which are applicable to the Tenant Work
          to be performed.

     2.   Claims for damages because of bodily injury, occupational sickness or
          disease, or death of employees under any applicable employer's
          liability law.

     3.   Claims for damages because of bodily injury, or death of any person
          other than Tenant's or Tenant Contractor's employees.

     4.   Claims for damages insured by usual personal injury liability coverage
          which are sustained (a) by any person as a result of an offense
          directly or indirectly related to the employment of such person by the
          Tenant or Tenant Contractor or (b) by any other person.

     5.   Claims for damages, other than to the Tenant Work itself, because of
          injury to or destruction of tangible property, including loss of use
          therefrom.

     6.   Claims for damages because of bodily injury or death of any person or
          property damage arising out of the ownership, maintenance or use of
          any motor vehicle.

     Such Tenant Contractors' Commercial General Liability Insurance shall
include premises/operations (including explosion, collapse and underground
coverage if such Tenant Work involves any underground work), elevators,
independent contractors, completed operations, and blanket contractual liability
on all written contracts, all including broad form property damage coverage.

                                     - 72 -
<Page>

     Tenant Contractors' Commercial General, Automobile, Employers and Umbrella
Liability Insurance shall be written for not less than limits of liability as
follows:

     a.   Commercial General Liability:
          Bodily Injury and Property Damage       As Required by EXHIBIT H-1.

     b.   Comprehensive Automobile Liability:
          Bodily Injury and Property Damage       $1,000,000 Each Person
                                                  $1,000,000 Each Occurrence

     c.   Employer's Liability:
          Each Accident                           $ 500,000
          Disease - Policy Limit                  $ 500,000
          Disease - Each Employee                 $ 500,000

     d.   Umbrella Liability:
          Bodily Injury and Property Damage       As Required by EXHIBIT H-1
                                                  (excess of coverages a, b & c
                                                  above)

     All subcontractors for such Tenant Contractors shall carry the same
coverages and limits as specified above, unless different limits are
specifically negotiated with Landlord.

     The foregoing policies shall contain a provision that coverages afforded
under the policies shall not be canceled or not renewed until at least sixty
(60) days' prior written notice has been given to the Landlord. Certificates of
Insurance showing such coverages to be in force shall be filed with the Landlord
prior to the commencement of any Tenant Work and prior to each renewal. Coverage
for Completed Operations must be maintained for three years following completion
of the work and certificates evidencing this coverage must be provided to the
Landlord.

     The minimum A.M. Best's rating of each insurer shall be A-/VII. Landlord
shall be named as an Additional Insured under such Tenant Contractors'
Commercial General and Umbrella Liability Insurance policies.

                                     - 73 -
<Page>

     Such Tenant Contractors' responsibilities include:

     -    Insuring all materials, on an All Risks basis for the full replacement
          cost, in transit and until delivered to the project site;

     -    insuring all tools and equipment used in the installation process;

     -    assuming costs within the deductible(s) if a property loss is caused
          by any Tenant Contractor's failure to take reasonable steps to prevent
          the loss; and

     -    protecting the site to prevent both natural and man-caused (i.e.,
          arson, theft, vandalism) losses.

PROPERTY INSURANCE LOSS ADJUSTMENT

     Any insured loss shall be adjusted with the Landlord and made payable to
the Landlord, subject to any applicable mortgagee clause.

                                     - 74 -
<Page>

                                   EXHIBIT H-1

        TENANT CONTRACTOR AND SUBCONTRACTOR INSURANCE LIMIT REQUIREMENTS

<Table>
<Caption>
                                                                 Trade Number for Limits
Division                     Trade Description                   Required
                                                                 (See Attached)
<S>                          <C>                                 <C>
1.   Sitework                Earthwork                           3
                             Excavation                          5
                             Grading                             2
                             Paving                              2
                             Piling/Caisson                      3
                             Retention                           4

2.   Concrete                Formwork                            5
                             Precasts                            5
                             Structural                          5

3.   Masonry                 Masonry                             5

4.   Metal and
     Structural              Metal Deck                          4
                             Miscellaneous Metals                2
                             Structural Steel                    5

5.   Carpentry               Millwork                            2
                             Rough Carpentry                     2
                             Wood Doors                          2
6.   Moisture
     Protection              Caulking                            3
                             Dampproofing                        3
                             Roofing/Sheet Metal                 5
                             Waterproofing                       3
</Table>

                                     - 75 -
<Page>

<Table>
<Caption>
                                                                 Trade Number for Limits
Division                     Trade Description                   Required
                                                                 (See Attached)
<S>                          <C>                                 <C>
7.   Doors, Windows
     and Glass               Curtainwall                         5
                             Glass, Glazing
                             and Aluminum                        3
                             Hardware                            1
                             Hollow Metal Work                   1

8.   Finishes                Acoustic                            2
                             Ceramic & Quarry                    2
                             Covering                            2
                             Lathe, Plaster & Drywall            2
                             Resilient Floor                     2
                             Paint & Vinyl Wall                  2

9.   Specialties             Access Flooring                     1
                             Partitions                          1
                             Toilet Accessories                  1

10.  Equipment               Crane Operations                    4

11.  Furnishings             Suppliers                           1

12.  Special
     Construction            Asbestos Abatement                  5
                             Blasting                            5

13.  Conveying
     Systems                 Elevators                           5
                             Escalators                          5
                             Conveyers                           3
                             Dumbwaiters                         3

14.  Mechanical              Fire Protection System              4
                             Plumbing                            4
</Table>

                                     - 76 -
<Page>

<Table>
<Caption>
                                                                 Trade Number for Limits
Division                     Trade Description                   Required
                                                                 (See Attached)
<S>                          <C>                                 <C>
15.  HVAC                                                        5

16.  Electrical              Electrical                          5

17.  Demolition              More than 3 stories                 10
                             Three (3) stories or less           5

     General Contractor      Major Project                       50

     General Contractor      Performing the following            10
                             Work: (a) new construction
                             under 4 stories and less than
                             150,000 sq. ft.; (b)
                             construction contract up to
                             $15,000,000; and (c)
                             renovation less the 15% of
                             existing structure.
</Table>

     Any unusual or specialized renovation or repair work undertaken by Tenant's
General Contractor with respect to this Lease may require other limits of
liability than those listed above. Landlord shall make any determination of
revised liability limits in consultation with its risk management staff.

Contractor and Subcontractor Insurance Limit Requirements by Trade Number

     The following are Limits of Liability required depending on the Trade
Number of the Contractor.

1.   $1,000,000 Each Occurrence
     $1,000,000 General Aggregate
     $1,000,000 Products & Completed Operations Aggregate

2.   $1,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate

3.   $2,000,000 Each Occurrence

                                     - 77 -
<Page>

     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $1,000,000 Umbrella Each Occurrence/Aggregate

     OR

     $1,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $2,000,000 Umbrella Each Occurrence/Aggregate

4.   $2,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $2,000,000 Umbrella Each Occurrence/Aggregate

     OR

     $1,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $3,000,000 Umbrella Each Occurrence/Aggregate

5.   $2,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $3,000,000 Umbrella Each Occurrence/Aggregate

     OR

     $1,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $4,000,000 Umbrella Each Occurrence/Aggregate

                                     - 78 -
<Page>

10.  $2,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $8,000,000 Umbrella Each Occurrence/Aggregate

     OR

     $1,000,000 Each Occurrence
     $2,000,000 General Aggregate
     $2,000,000 Products & Completed Operations Aggregate
     $9,000,000 Umbrella Each Occurrence/Aggregate

50.  $ 2,000,000 Each Occurrence
     $ 2,000,000 General Aggregate
     $ 2,000,000 Products & Completed Operations Aggregate
     $49,000,000 Umbrella Each Occurrence/Aggregate

     OR

     $ 1,000,000 Each Occurrence
     $ 2,000,000 General Aggregate
     $ 2,000,000 Products & Completed Operations Aggregate
     $50,000,000 Umbrella Each Occurrence/Aggregate

                                     - 79 -
<Page>

                                    EXHIBIT I

                               BASE BUILDING WORK

                                     - 80 -
<Page>

                                      PLANS

<Table>
<Caption>
ARCHITECTURAL                                                        DATE ISSUED
<S>                                                                     <C>
A0.00   General Notes & Drawing Index                                    12/2/03

D1.01   Demolition Plans                                                11/21/03
D1.02   Roof Demolition Scope                                           11/12/03
D1.03   Slab Demolition - Alternate                                     11/21/03

A1.00   Life Safety Plans                                                12/2/03
A1.01   Level One                                                        12/2/03
A1.02   Level Two                                                       11/21/03
A1.03   Roof Plan                                                        12/2/03

A2.01   Level One Reflected Ceiling Plan                                11/12/03
A2.02   Level Two Reflected Ceiling Plan                                11/21/03

A3.01   Exterior Elevations                                             11/21/03

A4.21   Exterior Details                                                11/21/03
A4.22   Canopy Details                                                  11/21/03
A4.41   Window Types                                                    11/21/03

A5.01   Stair and Elevator Sections                                     11/21/03
A5.02   Stair Section                                                   11/21/03
A5.03   Stair and Elevator Details                                      11/12/03

A6.01   Enlarged Floor Plans & Interior Elev.                            12/2/03
A6.02   Toilet Room Elevations                                          11/21/03
A6.10   Interior Details                                                11/21/03

A7.01   Door and Frame Types                                             12/2/03
A7.02   Door Details                                                    11/21/03
A7.11   Partition Types, Details and Notes                               12/2/03

A8.01   Finish Schedule and Legend                                      11/21/03

STRUCTURAL

S0.1    General Notes 1                                                 11/12/03
S0.2    General Notes 11                                                11/12/03

S1.1    Foundation Plan                                                 11/21/03

S1.2    Existing Second Floor Framing Plan                               12/2/03
S1.3    Existing Roof Framing Plan                                       12/2/03
S1.4    New Dunnage Framing Plan                                        11/21/03

S3.1    Typical Concrete Section & Det. 1                               11/21/03
</Table>

<Page>

<Table>
<S>     <C>                                                             <C>
S4.1    Typical Steel Sections & Det. II                                11/12/03

S5.1    Foundation Sections                                             11/21/03
S5.2    Sections and Details                                             12/2/03

FIRE PROTECTION

FP0.01  Fire Protection Leg. & Diag Sheet                               11/12/03

FP1.01  Fire Protection Level 1 Floor Plan                              11/21/03
FP1.02  Fire Protection Level 2 Floor Plan                              11/21/03

FIRE ALARM

FA0.01  Fire Alarm Leg. & Diagrams Sheet                                11/12/03

FA1.01  Fire Alarm Level 1 Floor Plan                                   11/21/03
FA1.02  Fire Alarm level 2 Floor Plan                                   11/21/03

PLUMBING

P0.01   Plumbing Legend, Diag. & Part Plans                             11/21/03

P1.01   Plumbing First Floor Plan                                       11/21/03
P1.02   Plumbing Second Floor Plan                                      11/21/03
P1.03   Plumbing Roof Plan                                              11/21/03

ELECTRICAL

E0.01   Electrical Legend, Notes and Schedules                          11/21/03
E0.02   Electrical Site Plan and Details                                11/21/03

E1.01   Electrical Level One Lighting & Power F                         11/21/03
E1.02   Electrical Level Two Lighting & Power F                         11/21/03
E1.03   Electrical Roof Plan                                            11/21/03

E2.01   Electrical Existing Distribution Riser Dia                      11/21/03
E2.02   Electrical New Distribution Riser Diag.                         11/21/03
E2.03   Electrical Schedules                                            11/21/03

HVAC
</Table>

<Page>

<Table>
<S>                                                                     <C>
H0.01   HVAC Legend and General Notes                                   11/12/03
H0.02   HVAC Schedules                                                  11/21/03
H0.03   HVAC Details                                                    11/21/03
H0.04   HVAC Hot Water Flow Diagram                                     11/21/03

H1.01   HVAC First Floor Demolition Plan                                11/21/03
H1.02   HVAC First Floor Ductwork Plan                                  11/21/03

H2.01   HVAC Second Floor Demolition Plan                               11/21/03
H2.02   HVAC Second Floor Ductwork Plan                                 11/21/03
H2.03   HVAC Second Floor Piping Plan                                   11/21/03

H3.01   HVAC Roof Demolition Plan                                       11/21/03
H3.02   HVAC New Work Plan (Option 1)                                   11/21/03
H3.02   HVAC New Work Plan (Option 2)                                   11/12/03
</Table>

<Page>

                                  SPECIFICATIONS

21 ERIE REALTY TRUST                                           November 25, 2003
Tsoi/Kobus & Associates, Inc., Architects, 23019-00

<Table>
<Caption>
LATEST DATE                       TABLE OF CONTENTS
<S>                               <C>
11/12/03                          Section 00330 - Existing Conditions
                                  Appendix: Geotechnical Information
                                  Appendix: Existing Hazardous Material Information
1997 Edition                      AIA A201 General Conditions of the Contract For Construction
11/12/03                          Section 00840 - Insurance Requirements
11/12/03                          Section 00880 - Computer File Transmittal Agreement
11/12/03                          Section 00938 - Requests for Information

                                  DIVISION 1 - GENERAL REQUIREMENTS
11/12/03                          Section 01100 - Summary
11/12/03                          Section 01116 - Engineering By Contractor
11/12/03                          Section 01150 - Air Quality
11/12/03                          Section 01200 - Price and Payment Procedures
11/12/03                          Section 01210 - Allowances
                                  Appendix: Schedule of Allowances
11/12/03                          Section 01230 - Alternates
11/12/03                          Section 01270 - Unit Prices
11/12/03                          Section 01300 - Administrative Requirements
11/12/03                          Section 01330 - Submittal Procedures
11/12/03                          Section 01360 - Safety
11/12/03                          Section 01400 - Quality Requirements
11/12/03                          Section 01452 - In Place Samples
11/12/03                          Section 01465 - Field Testing of Exterior Wall Assemblies
11/12/03                          Section 01480 - Remedial Work to Correct Errors
11/12/03                          Section 01500 - Temporary Facilities and Controls
11/12/03                          Section 01600 - Product Requirements
11/12/03                          Section 01700 - Execution Requirements
11/12/03                          Section 01733 - Cutting Requirements
11/12/03                          Section 01739 - Selective Demolition
11/12/03                          Section 01784 - Warranties
11/12/03                          Section 01892 - Renovation Requirements
11/12/03                          Section 01925 - Unknown Materials Procedures

                                  DIVISION 2 - SITE CONSTRUCTION

                                  DIVISION 3 - CONCRETE
11/25/03  Addendum 1              Section 03540 - Cementitious Underlayment

                                  DIVISION 4 - MASONRY
11/12/03                          Section 04065 - Masonry Mortar and Grout
11/12/03                          Section 04080 - Masonry Anchors and Reinforcing
11/12/03                          Section 04209 - Salvaged Masonry Units
11/12/03                          Section 04212 - Brick
11/12/03                          Section 04220 - Concrete Masonry
11/12/03                          Section 04810 - Unit Masonry Assemblies
11/12/03                          Section 04912 - Masonry Renovation
11/12/03                          Section 04913 - Masonry Restoration
11/12/03                          Section 04915 - Masonry Repointing
11/12/03                          Section 04930 - Cleaning Existing Masonry

                                  DIVISION 5 - METALS
11/12/03                          Section 05080 - Factory Applied Metal Coatings
11/12/03                          Section 05085 - Hot Dip Galvanizing
</Table>

                            Table of Contents 1 of 3

<Page>

21 ERIE REALTY TRUST                                           November 25, 2003
Tsoi/Kobus & Associates, Inc., Architects, 23019-00

<Table>
<S>                               <C>
11/12/03                          Section 05092 - Welding Metals
11/25/03  Addendum 1              Section 05430 - Slotted Channel Framing
11/12/03                          Section 05502 - Miscellaneous Metal Fabrications
11/12/03                          Section 05505 - Steel Lintels
11/12/03                          Section 05512 - Steel Stairs
11/12/03                          Section 05515 - Custom Steel Ladders
11/12/03                          Section 05522 - Steel Railings
11/12/03                          Section 05592 - Elevator Metals
11/12/03                          Section 05750 - Ornamental Metal Canopy Supports
11/12/03                          Section 05752 - Counter Top Supports

                                  DIVISION 6 - WOOD AND PLASTICS
11/12/03                          Section 06062 - Interior Wood Types
11/12/03                          Section 06082 - Shop Finishes For Interior Wood
11/12/03                          Section 06105 - Wood Blocking
11/12/03                          Section 06110 - Wood Framing
11112/03                          Section 06162 - Wood Sheathing
11/12/03                          Section 06416 - Plastic Laminate Counter Tops
11/12/03                          Section 06452 - Interior Standing and Running Trim
11/12/03                          Section 06605 - Solid Surfacing Fabrications

                                  DIVISION 7 - THERMAL AND MOISTURE PROTECTION
11/12/03                          Section 07162 - Cementitious Waterproofing
11/12/03                          Section 07210 - Building Insulation
11/12/03                          Section 07260 - Vapor Retarders
11/12/03                          Section 07263 - Under Slab Vapor Retarder
11/12/03                          Section 07270 - Air Barrier System
11/12/03                          Section 07414 - Metal Wall Panels
11/12/03                          Section 07462 - Vinyl Siding
11/12/03                          Section 07535 - Single Ply Roof System
11/12/03                          Section 07599 - Roof Maintenance and Repairs
11/12/03                          Section 07602 - Sheet Metal Types
11/12/03                          Section 07652 - Flashings Built Into Walls
11/25/03  Addendum 1              Section 07662 - Interior Leak Protection
11/12/03                          Section 07712 - Roof Specialties
11/12/03                          Section 07716 - Custom Roof Edges
11/12/03                          Section 07723 - Ventilation Penthouse
11/12/03                          Section 07810 - Applied Fireproofing
11/12/03                          Section 07842 - Fire Stops and Smoke Stops
11/12/03                          Section 07912 - Compressible Fillers
11/12/03                          Section 07922 - Joint Sealers

                                  DIVISION 8 - DOORS AND WINDOWS
11/12/03                          Section 08110 - Steel Doors and Frames
11/12/03                          Section 08212 - Flush Wood Doors
11/12/03                          Section 08310 - Access Doors and Panels
11/12/03                          Section 08405 - Aluminum Entrances
11/12/03                          Section 08412 - Aluminum Store Fronts
11/12/03                          Section 08520 - Aluminum Windows
11/25/03  Addendum 1              Section 08633 - Glazed Canopy Assembly
11/12/03                          Section 08812 - Interior Glass
11/12/03                          Section 08813 - Exterior Glass
11/12/03                          Section 08830 - Mirrors
</Table>

                            Table of Contents 2 of 3

<Page>

21 ERIE REALTY TRUST                                           November 25, 2003
Tsoi/Kobus & Associates, Inc., Architects, 23019-00

<Table>
<S>                               <C>
                                  DIVISION 9 - FINISHES
11/12/03                          Section 09105 - Interior Light Gage Steel Framing
11/12/03                          Section 09230 - Plaster Fabrications
11/12/03                          Section 09252 - Gypsum Board
11/12/03                          Section 09254 - Interior Cement Board
11/12/03                          Section 09263 - Gypsum Shaft Wall
11/12/03                          Section 09302 - Tile
11/25/03  Addendum 1              Section 09510 - Acoustical Ceilings
11/12/03                          Section 09513 - Interior Metal Ceilings
11/12/03                          Section 09605 - Finish Floor Transitions
11/12/03                          Section 09609 - Subfloor Preparation
11/12/03                          Section 09652 - Resilient Base
11/12/03                          Section 09655 - Resilient Tile Flooring
11/12/03                          Section 09658 - Resilient Stair Finish
11/12/03                          Section 09822 - Acoustical Insulation
11/12/03                          Section 09825 - Acoustical Seals
11/12/03                          Section 09910 - Painting
11/12/03                          Section 09917 - Interior Variegated Paint
11/12/03                          Section 09919 - Repainting

                                  DIVISION 10 - SPECIALTIES
11/12/03                          Section 10160 - Metal Toilet Compartments
11/12/03                          Section 10210 - Wall Louvers
11/12/03                          Section 10440 - Interior Signage
11/12/03                          Section 10522 - Fire Extinguishers
11/12/03                          Section 10607 - Interior Chain Link Fence Partitions
11/12/03                          Section 10810 - Toilet Accessories

                                  DIVISION 11 - EQUIPMENT

                                  DIVISION 12 - FURNISHINGS
11/25/03  Addendum 1              Section 12482 - Entrance Mats

                                  DIVISION 13 - SPECIAL CONSTRUCTION

                                  DIVISION 14 - CONVEYING SYSTEMS
11/12/03                          Section 14240 - Hydraulic Elevator

                                  DIVISION 15 - MECHANICAL
11/12/03                          Section 15300 - Fire Protection & Narrative
11/21/03  Addendum 1              Section 15400 - Plumbing
11/12/03                          Section 15500 - HVAC

                                  DIVISION 16 - ELECTRICAL
11/12/03                          Section 16000 - Electrical
11/12/03                          Section 16700 - Fire Alarm

                                  End of Contents
</Table>

                            Table of Contents 3 of 3

<Page>

                                     EXHIBIT J

                               TENANT RELATED WORK

1.   Passenger elevator, shaft, and elevator machine room
2.   Tenant entry stairs in the lobby along Erie Street
3.   Service (back) stairs in the service lobby along Waverly Street
4.   Fence enclosures in first floor mechanical room along Merriam Street
5.   Rooftop HVAC units servicing the Premises tied into existing ductwork
6.   Electrical service from the NSTAR vault to the electrical room in the
       Storage room on the 2nd floor of the Premises
7.   New (future) mechanical shafts from the roof, through the Premises to the
       1st floor
8.   Structural infill at the 2nd floor of the Premises where the former entry
       stairs were located

                                     - 81 -
<Page>

                                    EXHIBIT L

                               FINISH WORK LETTER

All Finish Work shall be constructed in accordance with the provisions of
Section 10.05 of the Lease and this Finish Work Letter, which is incorporated
into the Lease by reference.

L.1  CONSTRUCTION DOCUMENTS. Tenant shall prepare, at Tenant's expense (subject
to reimbursement from the Finish Work Allowance under Section L.2), Construction
Documents (as defined in Section 10.05 of the Lease) for the Finish Work.

     In accordance with and subject to the provisions of Section 10.05, Landlord
shall approve all of the Finish Work on the Construction Documents.

     Landlord has approved, Olson, Lewis & Dioli as Tenant's Architect (as
defined in Section 10.05 of the Lease) for the Finish Work. If an architect
other than Landlord's architect is selected by Tenant, Tenant shall provide a
letter from such architect to Landlord stating that the architect has carefully
reviewed the requirements of this Exhibit L, of Section 10.05 of the Lease, of
any design manual or handbook provided to Tenant by Landlord with respect to the
Finish Work, and of any Finish Work design schedule, and that the architect will
comply with all such requirements including without limitation the submission
deadlines stated in any Finish Work design schedule. Tenant shall also retain
the services of the electrical and mechanical engineers engaged by Landlord for
the Base Building Work, as well as Landlord's structural engineer if any portion
of Finish Work affects structural components of the Building. Even though such
engineers (and architect if Tenant engages Landlord's architect) have been
otherwise engaged by Landlord in connection with the Base Building Work, Tenant
shall be solely responsible for the liabilities and expenses of all
architectural and engineering services relating to the Finish Work (subject to
reimbursement from the Finish Work Allowance) and for the adequacy and
completeness of the Construction Documents submitted to Landlord. The
Construction Documents shall provide for the uniform exterior appearance of the
Building, including without limitation the use of Building standard window
blinds and Building standard light fixtures within 15 feet of each exterior
window.

     L.2  FINISH WORK ALLOWANCE. Landlord shall provide Tenant with an allowance
for the costs ("Allowance Costs") of constructing Finish Work in the Premises
for Tenant's initial occupancy (including, without limitation, architectural and
engineering fees with respect thereto up to a maximum amount in the aggregate
equal to $5.00 per rentable square foot of the Premises) in an amount not to
exceed $1,541,045 (the "Finish Work Allowance"). Notwithstanding the foregoing
or anything in the Lease to the contrary, up to $50,000 of the Finish Work
Allowance may be used for dismantling, moving, and reusing certain equipment
from Tenant's existing facility to and in the Premises and for communications
and computer cabling. All construction and design costs for the Premises

                                     - 82 -
<Page>

in excess of the Finish Work Allowance shall be paid for entirely by Tenant, and
Landlord shall not provide any reimbursement therefor.

     Landlord shall disburse the Finish Work Allowance at the time and in the
manner hereinafter described. For each disbursement, Tenant shall submit a
requisition package to Landlord, with an itemization of the costs being
requisitioned, a certificate by an officer of Tenant that all such costs are
Allowance Costs and have been incurred and paid for (unless Tenant elects for
payment directly to Tenant's Contractor or Architect, as set forth below) by
Tenant, and appropriate back-up documentation including, without limitation,
lien releases to the extent available pursuant to applicable law (in a form
approved by Landlord), and paid invoices and bills (from the previous
disbursement if Tenant elects for payment directly to Tenant's Contractor or
Architect). The final requisition package shall further include an executed
estoppel letter under the Lease and an original certificate of occupancy
(provided that if a certificate of occupancy is unavailable at the time of
Tenant's final requisition solely on account of the status of any Base Building
Work, Tenant shall supply a final certificate of occupancy when it becomes
available). At Tenant's election, Landlord shall make disbursements to Tenant
and Tenant's Contractor or (with respect to amounts on account of architectural
fees) Tenant's Architect. All disbursements shall be made by Landlord within
thirty (30) days of Landlord's receipt of Tenant's complete requisition package.
Prior to the first disbursement of the Finish Work Allowance, Tenant shall
provide Landlord with information as reasonably requested by Landlord to
substantiate the complete cost of the Finish Work, such as a certified budget
reasonably acceptable to Landlord, (such information, the "CONSTRUCTION BUDGET")
and shall provide Landlord with any changes thereto within two (2) business days
following any change (such approved costs and expenses, the "CONSTRUCTION
EXPENSES"). The Finish Work Allowance shall be payable by Landlord to Tenant on
a progress payment basis (but not more frequently than monthly) following the
Delivery Date in an amount equal to "LANDLORD'S SHARE" (defined below) of
Construction Expenses when and as actually paid (or incurred, if Tenant elects
to make payments directly to Tenant's Contractor or Architect) by Tenant.
Landlord and Tenant agree that both shall make payment of their respective
obligations for the Construction Expenses on a proportionate basis as described
below; and after Landlord's disbursement of the Finish Work Allowance, Tenant
shall be financially responsible for all remaining Construction Expenses for
Tenant's Finish Work. "Landlord's Share" shall mean the fraction (expressed as a
percentage), the numerator of which is the entire amount of the Finish Work
Allowance and the denominator of which is the entire amount of such Construction
Expenses. "TENANT'S EXCESS IMPROVEMENTS COST" means the amount (if a positive
number) of the costs paid by Tenant to construct the Finish Work less the Finish
Work Allowance. In no event shall Landlord be required to pay more than the
Finish Work Allowance. Tenant shall be entitled to a credit against Base Rent if
the Finish Work Allowance exceeds the total Construction Expenses required to be
funded by Landlord pursuant to this Section L.2, but in any event such credit
shall not exceed $10.00 per square foot of the Premises in the aggregate.

     L.3  FINISH WORK. Finish Work in the Premises shall be constructed by
Tenant

                                     - 83 -
<Page>

in accordance with, and subject to, the provisions of Section 10.05 of the
Lease. Landlord shall not be responsible for any aspects of the design or
construction of Finish Work, the correction of any defects therein, or any
delays in the completion thereof.

     L.4. [Intentionally omitted]

     L.5  FINISH WORK CHANGE ORDERS. Tenant may, from time to time, by written
order to Landlord on a form specified by Landlord ("Finish Work Change Order"),
request a change in the Finish Work shown on the Construction Documents, subject
to Landlord's approval as set forth below. The Construction Documents shall not
be modified in any material respect except with Landlord's prior written
approval; and all modifications to the Construction Documents, whether material
or not, shall be made only by Finish Work Change Order submitted to Landlord and
approved by Landlord under Section L.6.

     L.6  PERFORMANCE OF FINISH WORK BY TENANT. No Finish Work shall be
performed except in accordance with the Construction Documents, and any Finish
Work Change Orders, approved by Landlord. Landlord may delete from the
Construction Documents and any Finish Work Change Order, and need not cause to
be performed, any items or aspects of Finish Work which in Landlord's reasonable
judgment (i) would delay Base Building Work, (ii) would materially increase the
cost of operating the Building or performing any other work in the Building (for
the purpose of this clause, "materially" means increases in cost in the
aggregate of at least $10,000), (iii) are incompatible with the design, quality,
equipment or systems of the Building, (iv) would require unusual expense to
readapt the Premises to general purpose office use or (v) otherwise do not
comply with the provisions of this Lease (including, without limitation, Section
10.05). By its execution of the Lease, and submission of any Construction
Documents and Finish Work Change Orders, Tenant will be deemed to have approved
of, and shall be legally responsible for, such Construction Documents and Finish
Work Change Orders. Tenant shall be responsible for building standard costs of
Building services or facilities (such as electricity, HVAC, and cleaning)
required to implement the Finish Work.

     L.7  ACCEPTANCE OF EXISTING WORK. Tenant has inspected, and is satisfied
with, the "as is" condition of the Premises and the elements of Base Building
Work to be constructed therein, as more particularly described on Exhibits I and
J of this Lease.

     L.8  TENANT PAYMENTS. All payments required to be made by Tenant under this
Finish Work Letter (e.g. other than costs of the Finish Work subject to
reimbursement out of the Finish Work Allowance), whether to Landlord or to third
parties, shall be deemed "Additional Rent" for purposes of Section 4.02 of the
Lease.

     L.9  TENANT'S AUTHORIZED REPRESENTATIVE. Tenant's Authorized Representative
is Johan van Walsem and shall have full power and authority to act on behalf of
Tenant on any matters relating to Finish Work.

                                     - 84 -
<Page>

     L.10 ENTRY PRIOR TO COMMMENCEMENT. If and as long as Tenant does not
interfere in any material way with the construction of the Base Building Work,
including the Tenant Related Work (by causing disharmony, scheduling or
coordination difficulties, etc.), Tenant may, with prior approval of Landlord
(which shall not be unreasonably withheld), and at Tenant's sole risk and
expense, enter the Premises prior to the Term Commencement Date for the purpose
of commencing the Finish Work. Upon completion of the Construction Documents for
Tenant's Finish Work, Landlord, Tenant, Landlord's contractor, and Tenant's
Contractor shall meet to prepare a schedule to coordinate the Base Building Work
and the Finish Work in a manner so that all such work can be completed in an
expeditious and efficient manner (the "Coordination Schedule").

     Prior to the Term Commencement Date Tenant shall comply with and perform,
and shall cause its employees, agents, contractors, subcontractors, material
suppliers and laborers to comply with and perform, all Tenant's obligations
under this Lease except the obligations to pay Base Rent and Additional Rent and
other charges and other obligations the performance of which would be clearly
incompatible with the installation of Finish Work.

     Any Tenant Contractor (or any employee or agent of Tenant) performing any
work in the Premises prior to the Delivery Date shall be subject to all of the
terms, conditions and requirements of the Lease. Neither Tenant nor any Tenant
Contractor shall interfere in any way with construction of, nor damage, the Base
Building Work, and shall do all things reasonably requested by Landlord to
expedite construction of the Base Building Work, consistent with the
Coordination Schedule. Without limitation, Tenant shall require each Tenant
Contractor to adjust and coordinate any work or installation in or to the
Premises to meet the schedule or requirements of other work being performed by
or for Landlord throughout the Property which shall in all cases have
precedence. If Tenant or any Tenant Contractor fails so to adjust to the
schedule or requirements of Landlord, then such failure shall constitute Tenant
Delay (as hereafter defined). Neither Tenant nor any Tenant Contractor shall
cause any labor disharmony with Landlord's contractor, and Tenant shall be
responsible for all costs required to produce labor harmony in connection with
an entry under this Section and shall comply with any provisions of the Lease
governing labor harmony. In all events, Tenant shall indemnify the Indemnitees
in the manner provided in Section 9.02 of the Lease against any claim, loss or
cost arising out of any interference with, or damage to, the Base Building Work
or any other work at the Property or any increase in the cost thereof on account
in whole or in part of any act, omission, neglect or default by Tenant or any
Tenant Contractor. Without limiting the generality of the foregoing, to the
extent that the commencement or performance of Base Building Work is delayed on
account in whole or in part of any act, omission, neglect, or default by Tenant
or any Tenant Contractor, then such delay shall constitute a Tenant Delay as
provided herein.

                                     - 85 -
<Page>

     Any requirements of any such Tenant Contractor for services from Landlord
or Landlord's contractor, such as hoisting, electrical or mechanical needs,
shall be paid for by Tenant (from the Finish Work Allowance to the extent
available pursuant to Section L.2) and arranged between such Tenant Contractor
and Landlord or Landlord's contractor. Should the work of any Tenant Contractor
depend on the installed field conditions of any item of the Base Building Work,
such Tenant Contractor shall ascertain such field conditions after installation
of such item of the Base Building Work. Neither Landlord nor Landlord's
contractor shall ever be required or obliged to alter the method, time or manner
for performing any of the Base Building Work, or work elsewhere on the Property,
on account of the work of any such Tenant Contractor; however, Landlord and
Landlord's contractor shall utilize reasonable efforts to cause such work to be
performed consistent with the Coordination Schedule. Should Landlord's
contractor, including subcontractors working under such contractor, damage or
delay the work of any Tenant Contractor, then such Tenant Contractor, by
entering on the Premises, shall be deemed to have agreed not to prosecute any
claim against Landlord, but shall look solely to Landlord's contractor (or such
contractor's subcontractors) that allegedly caused the damage or delay. If any
such Tenant Contractor ever makes a claim against any Indemnitee (as such term
is defined in Section 9.02) directly, then Tenant shall indemnify such
Indemnitee in the manner provided in the Lease against such claim so long as
such Tenant Contractor's loss was not caused solely and directly by the
negligence or willful and wrongful act of such Indemnitee. Tenant shall cause
each Tenant Contractor performing work on the Premises to clean up regularly and
remove its debris from the Premises and Property. If any Tenant Contractor fails
so to clean up, then Landlord may cause its contractor to clean up and remove
debris, and Tenant shall pay all costs (including administrative costs) of such
cleanup and removal.

     L.11. TENANT DELAYS. A delay in the commencement, performance or completion
of the Base Building Work as a result of any of the following is referred to as
a "TENANT DELAY":

          (i)  any request by Tenant that Landlord delay the commmencement of,
or suspend the performance of, any Base Building Work (it being agreed that
Landlord is not required to comply with such request and may decline to comply
therewith in its sole discretion), or

          (ii) any other act or omission of Tenant, any Tenant Contractor (as
defined in Section 10), or any of their officers, employers, agents, or
contractors.

     For each day of Tenant Delay that causes the Delivery Date to occur after
February 1, 2004, the Delivery Date and Rent Commencement Date and Tenant's
obligation to pay Rent and additional charges shall be accelerated accordingly.

                                     - 86 -
<Page>

                                    EXHIBIT M

                                 INITIAL WARRANT

                                     - 87 -
<Page>

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE SOLD OR
TRANSFERRED UNLESS SUCH SALE OR TRANSFER IS IN ACCORDANCE WITH THE REGISTRATION
REQUIREMENTS OF SUCH ACT AND APPLICABLE LAWS OR SOME OTHER EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE LAWS IS AVAILABLE WITH
RESPECT THERETO.

                          COMMON STOCK PURCHASE WARRANT

Warrant No.__________                                     Number of Shares 5,000

                                 METABOLIX, INC.

                          COMMON STOCK PURCHASE WARRANT

                          Void Unless Exercised Before
               the Ten-Year Anniversary of Term Commencement Date

     1.   ISSUANCE. This Warrant is issued to 21 Erie Realty Trust by Metabolix,
Inc., a Delaware corporation (hereinafter with its successors called the
"Company"). This Warrant is issued in connection with that certain lease
agreement, dated as of December 29, 2003, by and among the Company and 21 Erie
Realty Trust (the "Lease Agreement").

     2.   PURCHASE PRICE; NUMBER OF SHARES. Subject to the terms and conditions
hereinafter set forth, the registered holder of this Warrant (the "Holder"),
commencing on the Term Commencement Date (as defined in the Lease Agreement), is
entitled upon surrender of this Warrant with the subscription form annexed
hereto duly executed, at the office of the Company, 303 Third Street, Cambridge,
Massachusetts 02142, or such other office as the Company shall notify the Holder
of in writing, to purchase from the Company at a price per share (the "Purchase
Price") of $2.70, fully paid and nonassessable shares of Common Stock, $.01 par
value, of the Company (the "Common Stock"). Until such time as this Warrant is
exercised in full or expires, the Purchase Price and the securities issuable
upon exercise of this Warrant are subject to adjustment as hereinafter provided.

     3.   PAYMENT OF PURCHASE PRICE. The Purchase Price may be paid (i) in cash
or by check, (ii) by the surrender by the Holder to the Company of any
promissory notes or other obligations issued by the Company, with all such notes
and obligations so surrendered being credited against the Purchase Price in an
amount equal to the principal amount thereof plus

<Page>

accrued interest to the date of surrender, (iii) through delivery by the Holder
to the Company of other securities issued by the Company, with such securities
being credited against the Purchase Price in an amount equal to the fair market
value thereof, as determined in good faith by the Board of Directors of the
Company (the "Board"), or (iv) by any combination of the foregoing. The Board
shall promptly respond in writing to an inquiry by the Holder as to the fair
market value of any securities the Holder may wish to deliver to the Company
pursuant to clause (iii) above.

     4.   NET ISSUE ELECTION. The Holder may elect to receive, without the
payment by the Holder of any additional consideration, shares equal to the value
of this Warrant or any portion hereof by the surrender of this Warrant or such
portion to the Company, with the net issue election notice annexed hereto duly
executed, at the office of the Company. Thereupon, the Company shall issue to
the Holder such number of fully paid and nonassessable shares of Common Stock as
is computed using the following formula:

                                X = Y (A-B)
                                    -------
                                       A

where

               X = the number of shares to be issued to the Holder pursuant to
          this Section 4.

               Y = the number of shares covered by this Warrant in respect of
          which the net issue election is made pursuant to this Section 4.

               A = the fair market value of one share of Common Stock, as
          determined in good faith by the Board, as at the time the net issue
          election is made pursuant to this Section 4.

               B = the Purchase Price in effect under this Warrant at the time
          the net issue election is made pursuant to this Section 4.

The Board shall promptly respond in writing to an inquiry by the Holder as to
the fair market value of one share of Common Stock.

     5.   PARTIAL EXERCISE. This Warrant may be exercised in part, and the
Holder shall be entitled to receive a new warrant, which shall be dated as of
the date of this Warrant, covering the number of shares in respect of which
this Warrant shall not have been exercised.

     6.   ISSUANCE DATE. The person or persons in whose name or names any,
certificate representing shares of Common Stock is issued hereunder shall be
deemed to have become the holder of record of the shares represented thereby as
at the close of business on the date this Warrant is exercised with respect to
such shares, whether or not the transfer books of the Company shall be closed.

                                      - 2 -

<Page>

     7.   EXPIRATION DATE. Unless terminated sooner as provided in Section 10,
this Warrant shall expire at the close of business on the ten-year anniversary
of the Term Commencement Date, and shall be void thereafter.

     8.   RESERVED SHARES; VALID ISSUANCE. The Company covenants that it will at
all times from and after the Term Commencement Date reserve and keep available
such number of its authorized shares of Common Stock, free from all preemptive
or similar rights therein, as will be sufficient to permit the exercise of this
Warrant in full. The Company further covenants that such shares as may be issued
pursuant to the exercise of this Warrant will, upon issuance, be duly and
validly issued, fully paid and nonassessable and free from all taxes, liens and
charges with respect to the issuance thereof.

     9.   DIVIDENDS. If, after the Term Commencement Date, the Company shall
subdivide the Common Stock, by split-up or otherwise, or combine the Common
Stock, or issue additional shares of Common Stock in payment of a stock dividend
on the Common Stock, the number of shares issuable on the exercise of this
Warrant shall forthwith be proportionately increased in the case of a
subdivision or stock dividend, or proportionately decreased in the case of a
combination, and the Purchase Price shall forthwith be proportionately decreased
in the case of a subdivision or stock dividend, or proportionately increased in
the case of a combination.

     10.  MERGERS AND RECLASSIFICATIONS. If after the Term Commencement Date
there shall be any (x) reclassification, capital reorganization or change of the
Common Stock (other than as a result of a subdivision, combination or stock
dividend provided for in Section 9 hereof), or (y) any consolidation of the
Company with, or merger of the Company into, another corporation or other
business organization (other than a consolidation or merger in which the Company
is the continuing corporation and which does not result in any reclassification
or change of the outstanding Common Stock), or (z) any sale or conveyance to
another corporation or other business organization of all or substantially all
of the assets of the Company, then, as a condition of such reclassification,
capital reorganization, change, consolidation, merger, sale or conveyance,
lawful provisions shall be made, and duly executed documents evidencing the same
from the Company or its successor shall be delivered to the Holder, so that the
Holder shall thereafter have the right to purchase, at a total price not to
exceed that payable upon the exercise of this Warrant in full, the kind and
amount of shares of stock and other securities and property receivable upon such
reclassification, capital reorganization, change, consolidation, merger, sale or
conveyance by a holder of the number of shares of Common Stock which might have
been purchased by the Holder immediately prior to such reclassification, capital
reorganization, change, consolidation, merger, sale or conveyance, and in any
such case appropriate provisions shall be made with respect to the rights and
interest of the Holder to the end that the provisions hereof shall thereafter be
applicable in relation to any shares of stock or other securities and property
thereafter deliverable upon exercise hereof. Notwithstanding the foregoing, if,
in connection with any consolidation, merger, sale or conveyance described in
clauses (y) or (z), above, the Company shall be required to cause this Warrant
to be terminated prior to the consummation of such transaction, the Company
shall provide written notice of such termination

                                      - 3 -

<Page>

event to the Holder and this Warrant shall terminate on the date that is 30 days
after the date of such notice to the Holder, and shall be void thereafter.

     11.  FRACTIONAL SHARES. In no event shall any fractional share of Common
Stock be issued upon any exercise of this Warrant. If, upon exercise of this
Warrant as an entirety, the Holder would, except as provided in this Section 11,
be entitled to receive a fractional share of Common Stock, then the Company
shall pay to the Holder, in cash or by check, the cash value of such fractional
share, based upon the fair market value of one share of Common Stock as of the
date of exercise, as determined in good faith by the Board.

     12.  CERTIFICATE OF ADJUSTMENT. Whenever the Purchase Price is adjusted, as
herein provided, the Company shall promptly deliver to the Holder a certificate
setting forth the Purchase Price after such adjustment and setting forth a brief
statement of the facts requiring such adjustment.

     13.  NOTICES OF RECORD DATE, ETC. In the event of:

          (a)  any taking by the Company of a record of the holders of any class
of securities for the purpose of determining the holders thereof who are
entitled to receive any dividend or other distribution, or any right to
subscribe for, purchase or otherwise acquire any shares of stock of any class or
any other securities or property, or to receive any other right,

          (b)  any reclassification of the capital stock of the Company, capital
reorganization of the Company, consolidation or merger involving the Company, or
sale or conveyance of all or substantially all of its assets, or

          (c)  any voluntary or involuntary dissolution, liquidation or
winding-up of the Company,

then and in each such event the Company will mail or cause to be mailed to the
Holder a notice specifying (i) the date on which any such record is to be taken
for the purpose of such dividend, distribution or right, and stating the amount
and character of such dividend, distribution or right, or (ii) the date on which
any such reclassification, capital reorganization, consolidation, merger, sale
or conveyance, dissolution, liquidation or winding-up is to take place, and the
time, if any is to be fixed, as of which the holders of record in respect of
such event are to be determined. Such notice shall be mailed at least 5 business
days (unless a longer period is required pursuant to the terms of Section 10,
above) prior to the date specified in such notice on which any such action is to
be taken.

     14. INVESTMENT REPRESENTATIONS. By accepting this Warrant, the Holder
represents and warrants that (a) the Holder is an "accredited investor" as that
term is defined in Rule 501(a) of Regulation D promulgated under the Securities
Act of 1933, (b) the Holder is acquiring the Warrant for its own account, and
not with a view to distribution or resale in violation of the Securities Act of
1933, and (c) the Holder will not sell or transfer the Warrant without

                                      - 4 -

<Page>

registration under applicable federal and state securities laws, or the
availability of exemptions therefrom, and then, only in accordance with Section
16 hereof.

     15.  AMENDMENT. The terms of this Warrant may be amended, modified or
waived only with the written consent of the Company and the Holder.

     16.  WARRANT REGISTER; LOST WARRANT, ETC.

          A.   The Company will maintain a register containing the name and
address of the registered Holder of this Warrant. The Holder may change its
address as shown on the warrant register by written notice to the Company
requesting such change. Any notice or written communication required or
permitted to be given to the Holder may be given by certified mail or delivered
to the Holder at its address as shown on the warrant register.

          B.   In case this Warrant shall be mutilated, lost, stolen or
destroyed, the Company shall issue a new warrant of like tenor and denomination
and deliver the same (i) in exchange and substitution for and upon surrender and
cancellation of any mutilated Warrant, or (ii) in lieu of any Warrant lost,
stolen or destroyed, upon receipt of evidence reasonably satisfactory to the
Company of the loss, theft or destruction of such Warrant (including a
reasonably detailed affidavit with respect to the circumstances of any loss,
theft or destruction) and of indemnity reasonably satisfactory to the Company.

          C.   Subject to (i) the prior written consent of the Company, which
consent shall not be unreasonably withheld, provided, however, that in no event
shall the Company's consent be required in connection with the transfer of this
Warrant with respect to all or any of the shares purchasable hereunder in
connection with a sale or financing of the premises described in the Lease
Agreement, and (ii) compliance with applicable federal and state securities
laws, this Warrant may be transferred by the Holder with respect to any or all
of the shares purchasable hereunder. Upon surrender of this Warrant to the
Company, together with the assignment hereof properly endorsed, for transfer of
this Warrant as an entirety by the Holder in accordance with this Section 16,
the Company shall issue a new warrant of the same denomination to the assignee.
Upon surrender of this Warrant to the Company, together with the assignment
hereof properly endorsed, by the Holder for transfer in accordance with this
Section 16 with respect to a portion of the shares of Common Stock purchasable
hereunder, the Company shall issue a new warrant to the assignee, in such
denomination as shall be requested by the Holder hereof, and shall issue to such
Holder a new warrant covering the number of shares in respect of which this
Warrant shall not have been transferred.

     17.  NO IMPAIRMENT. The Company will not, by amendment of its Amended and
Restated Certificate of Incorporation or through any reclassification, capital
reorganization, consolidation, merger, sale or conveyance of assets,
dissolution, liquidation, issue or sale of securities or any other voluntary
action, avoid or seek to avoid the observance or performance of any of the terms
of this Warrant, but will at all times in good faith assist in the carrying out
of all such terms and in the taking of all such action as may be necessary or
appropriate in order to

                                      - 5 -

<Page>

protect the rights of the Holder; provided, however, that the Company may cause
this Warrant to be terminated as provided in Section 10.

     18.  GOVERNING LAW. The provisions and terms of this Warrant shall be
governed by and construed in accordance with the internal laws of the
Commonwealth of Massachusetts without regard for the conflict of laws principles
therein.

     19.  SUCCESSORS AND ASSIGNS. This Warrant shall be binding upon the
Company's successors and assigns and shall inure to the benefit of the Holder's
successors, legal representatives and permitted assigns.

     20.  BUSINESS DAYS. If the last or appointed day for the taking of any
action required or the expiration of any right granted herein shall be a
Saturday or Sunday or a legal holiday in Massachusetts, then such action may be
taken or right may be exercised on the next succeeding day which is not a
Saturday or Sunday or such a legal holiday.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                      - 6 -

<Page>

                                               METABOLIX, INC.

Dated:
      -----------------, 2004
                                               By:
                                                  ------------------------------
                                               Name: Dr. James Barber
                                               Title: President

(Corporate Seal)

Attest:

--------------------------------------

                                      - 7 -

<Page>

                                  SUBSCRIPTION
                   (To be signed only on exercise of Warrant)

To: Metabolix, Inc.                             Date:_____________________

     The undersigned hereby subscribes for ________ shares of Common Stock
covered by this Warrant. The certificate(s) for such shares shall be issued in
the name of the undersigned or as otherwise indicated below:

                                               ------------------------------
                                               Signature

                                               ------------------------------
                                               Name for Registration

                                               ------------------------------
                                               Mailing Address

                            NET ISSUE ELECTION NOTICE

To:____________                                 Date:_____________________

     The undersigned hereby elects under Section 4 to surrender the right to
purchase _________ shares of Common Stock pursuant to this Warrant. The
certificate(s) for the shares issuable upon such net issue election shall be
issued in the name of the undersigned or as otherwise indicated below.

                                               ------------------------------
                                               Signature

                                               ------------------------------
                                               Name for Registration

                                               ------------------------------
                                               Mailing Address

<Page>

                                   ASSIGNMENT
                   (To be signed only on transfer of Warrant)

     For value received ____________________________ hereby sells, assigns and
transfers unto _________________________________________

_____________________________________________________________________
 (Please print or typewrite name and address of Assignee)

_____________________________________________________________________
the right represented by the within Warrant, and does hereby irrevocably
constitute and appoint ____________________ its attorney to transfer the within
Warrant on the books of the within named Company with full power of substitution
on the premises.

Dated:__________________

                                               _______________________________

In the Presence of:

_________________________

<Page>

                                    EXHIBIT N

                                FIRST OFFER SPACE

                                     - 88 -
<Page>

[Diagram of the first floor.]

<Page>

                                    EXHIBIT O

                           TERMINATION PAYMENT EXAMPLE

Assuming a brokerage commission of $550,000, with a termination date on the last
day of the 5th Lease Year, and no increases in CPI over the term of the lease up
to the termination date, the Termination Payment would be calculated as follows:

(1) The Finish Work Allowance of $1,585,980 amortized over 120 months without
interest = $13,216.5 per month.

$13,216.5 per month x 60 months remaining in the Initial Term = $792,990
unamortized as of the termination date.

(2) The brokerage commission of $550,000 amortized over 120 months without
interest = $4,583.33 per month.

$4,583.33 per month x 60 months = $275,000.

(3)$792,990 + $275,000 = $1,067,990

(4)(Then-effective Base Rent of $64,881 per month x 60)/15 = $259,524

(5)$1,067,990 plus $259,524 = Termination Payment of $1,327,514

(In any event, the Termination Payment will not be less than two times the
monthly Base Rent).

                                     - 89 -
<Page>

                                    EXHIBIT P

                     STANDARD FORM OF CONSENT TO A SUBLEASE

                               CONSENT TO SUBLEASE
                                 21 ERIE STREET

     THIS CONSENT TO SUBLEASE ("Consent Agreement") dated as of________, 200_,
is made with reference to that certain sublease (the "Sublease") dated
___________, 200_, by and between ___________, with an address at
___________("Tenant") and_________, with an address at _____________
("Subtenant"), and is entered into by and among 21 Erie Realty Trust, with an
address in care of c/o Lyme Properties, LLC, 101 Main Street, 18th Floor,
Cambridge, MA 02142 (together with its successors and assigns, "Landlord"),
Tenant and Subtenant, with reference to the following facts:

     (A)  Landlord and Tenant are the parties to that certain lease dated as of
___________, 200_ ("Master Lease") with respect to the Premises (as defined in
the Master Lease) located in the building known as 21 Erie Street (the
"Building");

     (B)  Tenant and Subtenant wish to enter into the Sublease;

     (C)  The Master Lease provides, inter alia, that Tenant may not enter into
the Sublease without Landlord's prior written consent;

          (D)  Tenant and Subtenant have presented the fully executed Sublease
(a true copy of which is attached hereto) to Landlord in connection with
Tenant's request for such consent, upon all of the terms and conditions
hereinafter appearing.

          NOW, THEREFORE, for good and valuable consideration, the parties agree
as follows:

          1.   Landlord hereby consents to Tenant entering into the Sublease
upon the terms and conditions set forth below.

          2.   This Consent shall not release Tenant from any existing or future
duty, obligation or liability to Landlord pursuant to the Master Lease, nor
shall this Consent change, modify or amend the Master Lease in any manner,
notwithstanding anything to the contrary in the Sublease. Without limiting the
generality of the foregoing, (a) this Consent shall not relieve Tenant from any
requirement set forth in the Master Lease that Tenant obtain Landlord's prior
written approval of any other subleases, assignments or other dispositions of
Tenant's interest in the Master Lease or the Premises (except as may be

                                     - 90 -
<Page>

expressly set forth in the Master Lease) or of Subtenant's interest in the
Sublease or the demised premises thereunder, and (b) this Consent shall not
constitute Landlord's consent to any alteration of the Premises.

            3. (a)  In the event of a Master Lease Termination (as
hereinafter defined), at the written request and sole option of Landlord,
Subtenant agrees to attorn to Landlord and to recognize Landlord as
Subtenant's landlord under the Sublease, upon the terms and conditions and at
the rental rate specified in the Sublease, and for the then remaining term of
the Sublease, except that Landlord shall not be bound by any provision of the
Sublease that in any way increases Landlord's duties, obligations or
liabilities to Subtenant beyond those owed to Tenant under the Master Lease
or by any provision that grants or attempts to grant Subtenant any rights,
privileges or benefits greater than those possessed by Tenant under the
Master Lease. Subtenant hereby waives any provisions of applicable law that
may permit Subtenant (i) to terminate the Sublease other than pursuant to its
terms or (ii) to surrender possession of the subleased premises in the event
of a Master Lease Termination; and Subtenant hereby agrees that the Sublease
shall not be affected in any way whatsoever by a Master Lease Termination in
the event Landlord requests Subtenant's attornment to and recognition of
Landlord except as set forth herein. In the event of a Master Lease
Termination as to which Landlord does not so request Subtenant's attornment
to and recognition of Landlord as set forth above, the Sublease shall
terminate.

          In no event shall Landlord ever (i) be liable to Subtenant for any
act, omission or breach of the Sublease by Tenant, (ii) be subject to any
offsets or defense that Subtenant might have against Tenant, (iii) be bound by
any rent or additional rent that Subtenant might have paid in advance to Tenant,
or (iv) be bound to honor any rights of Subtenant in any security deposit placed
by Subtenant except to the extent Tenant has specifically assigned and turned
over such security deposit to Landlord as set forth below.

          Tenant hereby agrees that in the event of a Master Lease Termination,
Tenant shall immediately pay or transfer to Landlord any security deposits,
rent, or other sums then held by Tenant in connection with the subleasing of the
Premises. Subtenant hereby agrees that under no circumstances whatsoever shall
Landlord be held in any way responsible or accountable for any security deposit
or any sums paid by Subtenant to Tenant except to the extent that Landlord has
actually received such sums from Tenant and has acknowledged their source, and
Subtenant shall have no claim to any security or other deposit made by Tenant
under the Master Lease.

               (b)  "Master Lease Termination" means any event that, by
voluntary or involuntary act or by operation of law, might cause or permit the
Master Lease (or Tenant's right to possess the Premises under the Master Lease)
to be terminated, expire, be canceled, be foreclosed against, or otherwise come
to an end, including but not limited to (1) a default by Tenant under the Master
Lease or any of the terms and provisions

                                     - 91 -
<Page>

hereof; (2) foreclosure proceedings brought by the holder of any mortgage or
deed of trust to which the Master Lease is subject; (3) the termination of
Tenant's leasehold estate by dispossession proceeding or otherwise; or (4) the
expiration or termination of the Master Lease in accordance with its terms.

          4.   Subtenant shall be liable to Landlord, jointly and severally with
Tenant, to the extent of the obligations undertaken by or attributable to
Subtenant under the Sublease, for the performance of Tenant's agreements under
the Master Lease. Landlord may elect to receive directly from Subtenant all sums
due or payable to Tenant by Subtenant pursuant to the Sublease, and upon receipt
of Landlord's notice, Subtenant shall thereafter pay to Landlord any and all
sums becoming due or payable under the Sublease and Tenant shall receive from
Landlord a corresponding credit for such sums actually received by Landlord
against any and all payments then owing from Tenant under the Master Lease.
Neither the service of such written notice nor the receipt of such direct
payments shall cause Landlord to assume any of Tenant's duties, obligations
and/or liabilities under the Sublease, nor shall such event impose upon Landlord
the duty or obligation to honor the Sublease in the event of a Master Lease
Termination, nor subsequently to accept any purported attornment by Subtenant
not elected by Landlord pursuant to Section 3(a) hereof.

          5.   Subtenant hereby acknowledges that it is familiar with all of the
terms and provisions of the Master Lease and agrees not to do or omit to do
anything that would cause Tenant to be in breach of the Master Lease. Any such
act or omission shall also constitute a breach of the Master Lease, and this
Consent and shall entitle Landlord to recover any damage, loss, cost, or expense
that it thereby suffers from Tenant and Subtenant, jointly and severally.
Without limiting the generality of the foregoing, Subtenant shall comply with
and be subject to the provisions of the Master Lease regarding Tenant's
insurance (to the extent the same relate to the subleased premises) and waivers
of subrogation and, upon Landlord's request from time to time, shall provide
Landlord with such evidence of such compliance. To the extent that any provision
of the Sublease is inconsistent with the provisions of the Master Lease,
Subtenant agrees that it shall be bound by any stricter provision set forth in
the Master Lease.

          6.   Tenant and Subtenant, jointly and severally, shall be liable to
reimburse Landlord for any expenses, including reasonable attorneys' fees,
incurred in enforcing any of the terms or provisions of this Consent.

          7.   Tenant and Subtenant represent and warrant to Landlord that the
copy of the Sublease attached hereto is a true and complete copy of the
Sublease, that there are no other agreements (oral or written) between Tenant
and Subtenant with respect to the subleased premises, and that no termination or
modification of the Sublease will be binding upon Landlord unless Landlord shall
have given its prior written consent thereto. If the Master Lease has been
guaranteed, then Tenant shall deliver to Landlord a written approval

                                     - 92 -
<Page>

of the Sublease and this Consent by each such guarantor.

          8.   The agreements contained herein constitute the entire
understanding between the parties with respect to the subject matter hereof, and
shall supersede all prior agreements, written or oral. Tenant and Subtenant
warrant and agree that neither Landlord nor any of its agents or other
representatives have made any representations concerning the Premises, their
condition, the Sublease, or the Master Lease.

          9.   Notice required or desired to be given hereunder shall be
effective either upon personal delivery or three (3) business days after deposit
in the United States mail, by registered or certified mail, return receipt
requested, addressed to parties at the addresses set forth in this Consent (and
if no addresses are so listed, then to the Landlord at the address set forth in
the Master Lease for the payment of rent, or to Tenant or Subtenant at the
address of the Premises or of the subleased premises, respectively). Any party
may change its address for notice by giving notice in the manner hereinabove
provided.

          10.  Neither the Master Lease, the Sublease nor this Consent shall be
deemed, nor are they intended, to grant to Subtenant any rights whatsoever
against Landlord. Subtenant hereby acknowledges and agrees that its sole remedy
for any alleged or actual breach of its rights in connection with the Sublease
shall be solely against Tenant. Subtenant acknowledges and agrees that it is not
a third party beneficiary under the Master Lease and is not entitled to assert
any of Tenant's rights thereunder against Landlord, whether in its own right or
on behalf of Tenant.

          11.  Tenant and Subtenant agree, jointly and severally, to
indemnify and hold Landlord harmless from and against any loss, cost,
expense, damage, or liability, including reasonable attorneys' fees, incurred
as a result of a claim by any person or entity (i) that it is entitled to a
commission, finder's fee or like payment in connection with the Sublease or
(ii) relating to or arising out of the Sublease or any related agreements or
dealings.

          12.  Tenant shall promptly pay Landlord's expenses incurred in
connection with Tenant's request for consent of this Sublease, as and to the
extent provided in the Master Lease.

          13.  Landlord shall not be considered to have consented to the
Sublease until this Consent is executed and delivered by Landlord, Tenant,
and Subtenant and approved by the holder of any mortgage on the Building
having a right to approve the Sublease. Any liability of Landlord to Tenant
under or in connection with this Consent, and any liability of Landlord to
Subtenant, including without limitation liability under or in connection with
the Sublease or arising in any way from Subtenant's use or occupancy of the
subleased premises, shall be limited to the same extent as Landlord's
liability to Tenant is limited under the Master Lease.

                                     - 93 -
<Page>

     14.  This Consent shall be binding upon and shall inure to the benefit of
Landlord, Tenant, and Subtenant and their respective successors and permitted
assigns.

     15.  This Consent may be executed in multiple counterparts, each of which
shall be deemed an original and all of which together shall constitute a single
agreement, and shall be governed by the laws of The Commonwealth of
Massachusetts.

     EXECUTED under seal as of the date first written above.

                                        LANDLORD:

                                        21 ERIE REALTY TRUST

                                        By:
                                           --------------------------

                                        TENANT:

                                        METABOLIX, INC.

                                        By:
                                           --------------------------
                                               Name:
                                                    -----------------
                                               Title:
                                                     ----------------

                                        SUBTENANT

                                        -----------------------------
                                        Name:
                                        Title:

                                     - 94 -

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00109-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00109-of-00352.parquet"}]]