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                                                                   EXHIBIT 10.15

                                                         MM Equity No.__________

                                      LEASE

                  THIS LEASE, made as of September 26, 2003, by and between
THREE HUNDRED THIRD STREET LLC, a Delaware limited liability company
("Landlord") having an address in care of CORNERSTONE REAL ESTATE ADVISERS,
INC., Suite 1700, One Financial Plaza, Hartford, Connecticut 06103 and ALNYLAM
PHARMACEUTICALS, INC., a Delaware corporation ("Tenant") having its principal
office at 790 Memorial Drive, Cambridge, MA 02139.

                                      INDEX

Article  Title

 1.               Basic Provisions
 2.               Premises, Term and Rent Commencement Date
 3.               Rent
 4.               Taxes and Operating Expenses
 5.               Landlord's Work, Tenant's Work, Alterations and Additions
 6.               Use
 7.               Services
 8.               Insurance
 9.               Indemnification
10.               Casualty Damage
11.               Condemnation
12.               Repair and Maintenance
13.               Inspection of Premises
14.               Surrender of Premises
15.               Holding Over
16.               Subletting and Assignment
17.               Subordination, Attornment and Mortgagee Protection
18.               Estoppel Certificate
19.               Defaults
20.               Remedies of Landlord
21.               Quiet Enjoyment
22.               Accord and Satisfaction
23.               Security Deposit
24.               Brokerage Commission
25.               Force Majeure
26.               Parking
27.               Hazardous Materials
28.               Additional Rights Reserved by Landlord
29.               Defined Terms
30.               Miscellaneous Provisions
31.               Right of First Refusal

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                                    EXHIBITS

Exhibit A         Plan Showing the Building and Premises
Exhibit B         Landlord's Work Letter
Exhibit B-1       Construction Schedule for Landlord's Work
Exhibit C         Tenant's Work
Exhibit D         Building's Rules and Regulations; Janitorial Specifications
Exhibit E         Rent Commencement Date Confirmation
Exhibit F         Signage

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                                ARTICLE 1.

                             BASIC PROVISIONS

A.    Tenant's Trade Name: Alnylam Pharmaceuticals, Inc.

B.    Tenant's Address:

               Prior to Rent Commencement Date: 790 Memorial Drive,
               Cambridge, MA 02139

               After the Rent Commencement Date: at the Premises

C.    Office Building Address: 300 Third Street, Cambridge, Massachusetts

D.    Premises:                  Square feet (Rentable): A total of
                                 approximately 44,058 comprised of 32,537
                                 square feet on Level 03 (the "Third Floor
                                 Premises"), 10,605 square feet on Level 04
                                 (the "Fourth Floor Premises"), 366 square
                                 feet relating to the rooftop penthouse, 185
                                 square feet relating to the acid
                                 neutralization room and 365 square feet
                                 relating to the Level P-1 chemical storage
                                 room (the rooftop penthouse, acid
                                 neutralization room and chemical storage
                                 room are hereinafter collectively referred
                                 to as the "Peripheral Spaces")

E.    Landlord:                  Three Hundred Third Street LLC

F.    Landlord's Address:             c/o Cornerstone Real Estate Advisers, Inc.
                                      Suite 1700
                                      One Financial Plaza
                                      Hartford, Connecticut 06103
                                      Attention: Northeast Regional Director

                                      And a copy to: Attention: David Romano,
                                              Vice President, Asset Manager

G.    Building Manager/Address:       Beal & Co., Inc.
                                      177 Milk Street Boston, MA
                                      02109-3410
                                      Attention: Michael Manzo

H.    Effective Date:            Upon delivery of possession of the Premises
                                 to Tenant

      Rent Commencement Date:    The earlier to occur of (i) April 1, 2004 or
                                 (ii) the date Tenant takes occupancy of any
                                 portion of the Premises for the conduct of
                                 business provided, however, that, with
                                 respect to the Fourth Floor Premises only,
                                 the Rent Commencement Date shall be the
                                 earlier to occur of (i) September 1, 2005 or
                                 (ii) the date Tenant takes occupancy of any
                                 portion of the Fourth Floor Premises for the
                                 conduct of business.

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I.       Expiration Date:           September 30, 2011

J.       Security Deposit:          12 months Monthly Rent plus Estimated
                                    Operating Expenses (which, subject to
                                    adjustment, is equal to $2,313,045.00 as of
                                    the date hereof)

K.       Monthly Rent:     Lease Years 1 - 4:             $41.50 per square foot

                           Lease Years 5 - 9/30/2011:     $45.50 per square foot

L.       Operating Expenses: Tenant to pay its Pro Rata Share

M.       Taxes: Tenant to pay its Pro Rata Share

N.       Tenant's Pro Rata Share: Tenant's Pro Rata Share shall be determined by
         and adjusted by Landlord from time to time by dividing the Tenant's
         Rentable Square Feet of the Premises by the rentable area of the
         Building and multiplying the resulting quotient, to the second decimal
         place, by one hundred. Notwithstanding the foregoing, with respect to
         (1) the central HVAC system and (2) the acid neutralization room,
         Tenant's Pro Rata Share shall be determined based upon actual usage
         utilizing a commercially reasonable engineering analysis.

O.       Normal Business Hours of the Building:

         Monday through Friday: 8:00 a.m. to 6:00 p.m.
         Saturday: 8:00 a.m. to 1:00 p.m.
         (Excepting local and national holidays)

         Additional Business Hours of the Building: All other times of every
         week, during which Tenant shall have access and, as set forth in
         Article 7, Landlord shall provide building services at designated
         costs.

P.       Use: Laboratory, research and development, animal research, executive,
         administrative and general office purposes, subject to compliance with
         Laws

Q.       Brokers: Meredith & Grew, Incorporated and T3 Realty Advisors

R.       Parking Fee: Fair market parking rates, as adjusted from time to time
         Parking Spaces: 45 non-reserved spaces

S.       Building Amenities: Included in the Monthly Rent are all building
         amenities (other than parking) including, without limitation, lobby
         security station, showers, lockers and bicycle storage.

         The foregoing provisions shall be interpreted and applied in accordance
with the other provisions of this Lease set forth below. The capitalized terms,
and the terms defined in Article 29, shall have the meanings set forth herein or
therein (unless otherwise modified in the Lease) when used as capitalized terms
in other provisions of the Lease. Landlord and Tenant hereby stipulate that the
Premises contain the number of square feet specified in Article 1(D) above.

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                                   ARTICLE 2.

                      PREMISES, TERM AND COMMENCEMENT DATE

                  Subject to the terms and conditions set forth herein, Landlord
hereby leases and demises to Tenant and Tenant hereby takes and leases from
Landlord that certain space identified in Article 1(D) and shown on a plan
attached hereto as Exhibit A ("Premises"), together with Tenant's right to use
the Peripheral Spaces, for a term ("Term") commencing on the Effective Date and
ending on the Expiration Date set forth in Article 1 (the "Original Term"),
unless sooner terminated or extended as provided herein. The actual square
footage in the Premises and the Building shall be reasonably determined by
Landlord's architect, calculated in accordance with the ANSI/BOMA Z 95.1 (1996)
method of measurement. Tenant shall have the right to review and confirm such
measurements within thirty (30) days of the date Landlord's architect completes
such measurements and delivers the results thereof to Tenant. Upon Tenant's
review and confirmation, the certificate of Landlord's architect as to square
footage shall be binding upon both parties hereto and such determined square
footage shall be used in all calculations based on square footage throughout
this Lease. The Rent Commencement Date set forth in Article 1 shall be advanced
to such earlier date as Tenant commences occupancy of the Premises for the
conduct of its business. Such date shall be confirmed by execution of the Rent
Commencement Date Confirmation in the form as set forth in Exhibit E, which
Tenant shall execute and return to Landlord within ten (10) business days after
receipt thereof. If Landlord delays delivering possession of the Premises or
substantial completion of any Landlord's Work under Exhibit B, this Lease shall
not be void or voidable, except as provided in Article 5, and Landlord shall
have no liability for loss or damage resulting therefrom.

         Extension: Provided that, at the time Tenant elects to exercise the
option herein granted and at the time of the commencement of the Extended Term
(as hereinafter defined), (i) this Lease is in full force and effect, (ii)
Tenant is not in default hereunder beyond applicable notice and cure period(s)
(which default may be waived by Landlord at its sole discretion and may not be
used by Tenant as a means to negate the effectiveness of Tenant's exercise of
the option set forth herein), Tenant shall have the option to extend the Term of
this Lease for two (2) extended terms of five (5) years each (each, an "Extended
Term"). The Extended Term shall commence immediately following the end of the
Original Term or the first Extended Term, as the case may be. All terms and
conditions applicable during the Original Term shall apply during each Extended
Term including without limitation the obligation to pay Operating Expenses and
Taxes except that (i) Tenant shall have no further right to extend the Term
beyond the second Extended Term hereinabove provided, (ii) Monthly Rent shall be
as provided herein, and (iii) Tenant shall not be entitled to Tenant's
Construction Allowance or any other contribution by Landlord to the cost of
improvements or alterations to the Premises.

         Tenant shall exercise its option to extend this Lease for the Extended
Term by giving Landlord written notice of its election to extend (the "Notice to
Extend"), which notice shall apply to the entire Premises and shall be
irrevocable.

         Tenant may exercise its option to extend for each Extended Term by
giving Landlord a Notice to Extend not later than twelve (12) months prior to
the expiration date of the then current term, time being of the essence.

         If Tenant fails to give a timely Notice to Extend within the time
provided above, this Lease shall automatically expire at the end of the then
current term, unless sooner terminated as provided herein.

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         If Tenant exercises its option to extend the Term of this Lease for the
Extended Term by delivering the Notice to Extend, Tenant covenants to pay to
Landlord, during the Extended Term, Monthly Rent equal to 95 percent of the fair
market rent for comparable laboratory space in Cambridge, Massachusetts,
projected as of the commencement of the Extended Term, and a Parking Fee for the
Parking Spaces equal to the fair market parking fees, projected as of the
commencement of the Extended Term, in each case also referred to below
collectively as "Fair Market Rent." The computation can include appropriate
annual increases during each year of the Extended Term, if that is required to
arrive at fair market rent.

         Landlord shall notify Tenant of Landlord's proposed Monthly Rent and
Parking Fee for the Extended Term within thirty (30) days after Landlord's
receipt of Tenant's Notice to Extend, (but in no event prior to the last date
for Tenant to give the applicable Notice to Extend). Promptly after Landlord
gives Tenant Landlord's proposal for Fair Market Rent with respect to the
Extended Term, Landlord and Tenant shall commence negotiations to agree upon the
Fair Market Rent. If Landlord and Tenant are unable to reach agreement on the
Fair Market Rent within thirty (30) days after the date on which Landlord gives
Tenant Landlord's proposal for Fair Market Rent, then the Fair Market Rent shall
be determined as provided below.

         If Landlord and Tenant are unable to agree on the Fair Market Rent
within said thirty (30) day period, then within five (5) days thereafter,
Landlord and Tenant shall each simultaneously submit to the other in a sealed
envelope its good faith estimate of the Fair Market Rent. If the higher of such
estimates is not more than one hundred five percent (105%) of the lower of such
estimates, then the Fair Market Rent shall be the average of the two estimates.
If the matter is not resolved by the exchange of estimates, then Fair Market
Rent shall be determined by arbitration as hereinafter provided.

         Within seven (7) days after the exchange of estimates, the parties
shall select, as an arbitrator, a mutually acceptable member of the American
Society of Real Estate Counselors ("ASREC"), or a successor organization to
ASREC. If the parties cannot agree on such person, then within a second period
of seven (7) days, each shall select a member of ASREC and within a third period
of seven (7)days, the two appointed persons shall select a third member of ASREC
and the third person shall be the arbitrator. If one party shall fail to make
such appointment within said second seven (7) day period, then the person chosen
by the other party shall be the sole arbitrator.

         Once the arbitrator has been selected as provided for above, then, as
soon thereafter as practicable, but in any case within fourteen (14) days after
his or her appointment, the arbitrator shall determine the Fair Market Rent by
selecting either the Landlord's estimate of Fair Market Rent or the Tenant's
estimate of Fair Market Rent. There shall be no discovery or similar
proceedings. The arbitrator's decision as to which estimate of Fair Market Rent
shall be the Fair Market Rent for the Extended Term shall be rendered in writing
to both Landlord and Tenant and shall be final and binding upon them and shall
be the Monthly Rent and Parking Fee for the Extended Term. In determining the
Fair Market Rent with respect to the Monthly Rent and the Parking Fee, the
arbitrator shall not be required to select the same party's estimate of Fair
Market Rent for both the Monthly Rent and the Parking Fee, but shall have the
option to select one party's (i.e., Landlord's or Tenant's) estimate of Fair
Market Rent with respect to the Monthly Rent and the other party's estimate of
Fair Market Rent with respect to the Parking Fee.

         The costs of the arbitrator will be equally divided between Landlord
and Tenant. Any fees of any counsel engaged by Landlord or Tenant, however,
shall be borne by the party that retained such counsel.

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                                   ARTICLE 3.

                                      RENT

                  A.       Monthly Rent. Tenant shall pay Monthly Rent by wire
transfer, in advance, on or before the first day of each month of the Term
without demand, setoff or deduction. If the Term shall commence or end on a day
other than the first day of a month, the Monthly Rent for the first and last
partial month shall be prorated on a per diem basis. Upon the execution of this
Lease, Tenant shall pay one installment of Monthly Rent for the first full month
of the Term and a prorated Monthly Rent for any partial month which may precede
it.

                  B.       Additional Rent. All costs and expenses which Tenant
assumes or agrees to pay and any other sum payable by Tenant pursuant to this
Lease, including, without limitation, its share of Taxes and Operating Expenses,
shall be deemed Additional Rent.

                  C.       Rent. Monthly Rent, Additional Rent, Taxes and
Operating Expenses and any other amounts of every nature which Tenant is or
becomes obligated to pay Landlord under this Lease are herein referred to
collectively as "Rent", and all remedies applicable to the nonpayment of Rent
shall be applicable thereto.

                  D.       Place of Payment, Late Charge, Default Interest. Rent
and other charges required to be paid under this Lease, no matter how described,
shall be paid by Tenant to Landlord at the Building Manager's address listed in
Article 1, or to such other person and/or address as Landlord may designate in
writing, without any prior notice or demand therefor and without deduction or
set-off or counterclaim and without relief from any valuation or appraisement
laws. In the event Tenant fails to pay Rent due under this Lease within ten (10)
days of the due date of said Rent, Tenant shall pay to Landlord a late charge of
five percent (5%) of the amount overdue. Any Rent not paid when due shall also
bear interest at the Default Rate. This provision shall in no way be construed
to modify Tenant's obligation to pay Rent on or before the first (1st) day of
the month.

                  E.       Independent Covenants; Waiver. Tenant waives all
rights (i) to any abatement, suspension, deferment, reduction or deduction of or
from Rent, and (ii) to quit, terminate or surrender this Lease or the Premises
or any part thereof, except, in either case, as expressly provided herein.
Tenant hereby acknowledges and agrees that the obligations of Tenant hereunder
shall be separate and independent covenants and agreements, that Rent shall
continue to be payable in all events and that the obligations of Tenant
hereunder shall continue unaffected, unless the requirement to pay or perform
the same shall have been terminated pursuant to an express provision of this
Lease. Landlord and Tenant each acknowledges and agrees that the independent
nature of the obligations of Tenant hereunder represents fair, reasonable and
accepted commercial practice with respect to the type of property subject to
this Lease, and that this agreement is the product of free and informed
negotiation during which both Landlord and Tenant were represented by counsel
skilled in negotiating and drafting commercial leases in Massachusetts, and that
the acknowledgements and agreements contained herein are made with full
knowledge of the holding in Wesson v. Leone Enterprises, Inc., 437 Mass. 708
(2002). Such acknowledgements, agreements and waivers by Tenant are a material
inducement to Landlord entering into this Lease.

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                                   ARTICLE 4.

                          TAXES AND OPERATING EXPENSES

                  A.       Payment of Taxes and Operating Expenses. Commencing
on the Rent Commencement Date and during each month thereafter during the
initial Lease Term and any Extended Term, Tenant shall pay to Landlord, as
Additional Rent due concurrently with Monthly Rent, an amount equal to
one-twelfth (1/12) of Landlord's estimate (as determined by Landlord in its
reasonable discretion) of Tenant's Pro Rata Share of Operating Expenses paid or
incurred by Landlord with respect to the Property for the then current calendar
year and Taxes assessed against the Property (or estimated to be due by
governmental authority) during the then current calendar year (which may include
a portion of the Taxes assessed for more than one "tax year") (the "Estimated
Taxes and Operating Expenses"). Landlord shall provide the building services set
forth in this Lease.

                  B.       Reconciliation. As soon as practicable following the
end of each calendar year, and in any event within ninety (90) days after the
end of the applicable calendar year, Landlord shall submit to Tenant a statement
(the "Reconciliation") setting forth the actual Operating Expenses and Taxes for
the preceding calendar year and indicating whether any money is due to Landlord
or Tenant with respect to Operating Expenses or Taxes.

         If Tenant owes Landlord any money on account of Operating Expenses or
Taxes, Tenant shall pay such amount within fifteen (15) days after receipt of
the Reconciliation. In the event that Tenant has overpaid its obligation with
respect to Operating Expenses or Taxes for the preceding calendar year, Landlord
shall credit such overpayment against Tenant's subsequent obligations on account
of Operating Expenses or Taxes, (or refund such overpayment within fifteen (15)
days if the Term of the Lease has ended and Tenant has no further obligation to
Landlord), as the case may be.

         Landlord may commence proceedings to obtain an abatement or reduction
in taxes with attorneys and/or appraisers selected by Landlord and in the event
an abatement is obtained, Landlord shall refund Tenant's pro rata share of the
amount of the abatement as to which Tenant has paid its Pro Rata Share of Taxes,
after reducing the amount of the abatement by all reasonable expenses paid or
incurred by Landlord in obtaining such abatement.

                  C.       Changes in Information. If during any particular year
there is a change in the facts upon which Operating Expenses or Taxes are being
billed to Tenant, Landlord shall be permitted to revise its monthly billings to
Tenant on account of Operating Expenses or Taxes and Tenant shall thereafter pay
its monthly payments on account of Taxes and Operating Expenses in accordance
with Landlord's revised billing. In the event that Landlord provides a revised
billing, such billing shall be accompanied by a statement in reasonable detail
indicating the reason for the revisions in the monthly bills to Tenant on
account of Taxes and/or Operating Expenses.

                  If the Building is less than ninety-five percent (95%)
occupied during any particular Lease Year, Landlord may adjust those Operating
Expenses (but not Taxes) which are affected by Building occupancy for the
particular Lease Year, or portion thereof, as the case may be, to reflect an
occupancy of not less than ninety-five percent (95%) of all such rentable area
of the Building.

                  D.       Disputes Over Taxes or Operating Expenses.

         Selection of Accountants. If Tenant disputes the amount of an
adjustment or the proposed estimated bills for Taxes or Operating Expenses or
the actual bills for a Lease Year, Tenant shall give Landlord written notice of
such dispute within thirty (30) days after Landlord advises Tenant of such

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adjustment or bill, or the end of such Lease Year as the case may be. Tenant's
failure to give such notice shall waive its right to dispute the amounts so
determined. Tenant shall not be entitled to dispute the foregoing amounts if
Tenant is then in default hereunder beyond applicable notice and cure period(s).
If Tenant is entitled to and timely objects, Tenant shall have the right to
engage its own accountants ("Tenant's Accountants") for the purpose of verifying
the accuracy of the statement in dispute, or the reasonableness of the
adjustment or estimated increase or decrease. If Tenant's Accountants determine
that an error has been made, Landlord and Tenant's Accountants shall endeavor to
agree upon the matter. If they cannot agree within twenty (20) days from the
date Tenant's Accountants commence reviewing Landlord's records, Landlord and
Tenant's Accountants shall jointly select an independent certified public
accounting firm (the "Independent Accountant") which firm shall conclusively
determine whether the adjustment or estimated increase or decrease is
reasonable, and if not, what amount is reasonable. Both parties shall be bound
by such determination. If Tenant's Accountants do not participate in choosing an
Independent Accountant within twenty (20) days after receipt of notice by
Landlord, then Landlord's determination of the adjustment or estimated increase
or decrease shall be conclusively determined to be reasonable and Tenant shall
be bound thereby.

                  Any information obtained by Tenant's Accountants with respect
to Operating Expenses shall remain confidential except in connection with
litigation between Landlord and Tenant.

         Payment of Costs. All costs incurred by Tenant in obtaining Tenant's
Accountants and the cost of the Independent Accountant shall be paid by Tenant
unless Tenant's Accountants disclose an error, acknowledged by Landlord (or
found to have conclusively occurred by the Independent Accountant), of more than
five percent (5%) in the computation of the total amount of Taxes or Operating
Expenses as set forth in the statement submitted by Landlord with respect to the
matter in dispute; in which event Landlord shall pay the reasonable costs
incurred by Tenant in obtaining such audits. No subtenant shall have the right
to conduct an audit and no assignee shall conduct an audit for any period during
which such assignee was not in possession of the Premises.

         Continuation of Payments Pending Determination. Tenant shall continue
to timely pay Landlord the amount of the prior year's adjustment and adjusted
Additional Rent determined to be incorrect until the parties have agreed upon or
the Independent Accountant has determined the appropriate adjustment. Any
amounts so agreed or determined to be in excess of appropriate charges shall be
paid by Landlord to Tenant within fifteen (15) days of such agreement or
determination.

                  E.       Other Taxes. Tenant shall pay, prior to delinquency,
all taxes assessed against or levied upon trade fixtures, furnishings, equipment
and all other personal property of Tenant located in the Premises. So long as
every other lease of space in the Building contains the same provision and such
provisions are enforced by landlord, in the event any or all of Tenant's trade
fixtures, furnishings, equipment and other personal property shall be assessed
and taxed with property of Landlord, or if the cost or value of any leasehold
improvements in the Premises exceeds the cost or value of a Building-standard
build-out as determined by Landlord and, as a result, real property taxes for
the Property are increased, Tenant shall pay to Landlord its share of such taxes
within ten business (10) days after delivery to Tenant by Landlord of a
statement in writing setting forth the amount of such taxes applicable to
Tenant's property or above-standard improvements. Tenant shall assume and pay to
Landlord at the time of paying Rent, any excise, sales, use, rent, occupancy,
garage, parking, gross receipts or other taxes (other than net income taxes or
taxes in lieu of income taxes) which may be imposed on or on account of letting
of the Premises or the payment of Rent or any other sums due or payable
hereunder, and which Landlord may be required to pay or collect under any law
now in effect or hereafter enacted. Tenant shall pay directly to the party or
entity entitled thereto all business license fees, gross receipts taxes and
similar taxes and impositions which may from time to time be assessed

                                     - 9 -
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against or levied upon Tenant, as and when the same become due and before
delinquency. Notwithstanding anything to the contrary contained herein, any sums
payable by Tenant under this Article 4 shall not be included in the computation
of "Taxes."

                                   ARTICLE 5.

                         LANDLORD'S WORK, TENANT'S WORK,
                            ALTERATIONS AND ADDITIONS

                  A.       Landlord's Work. Landlord shall perform the work as
set forth in the work letter attached hereto as Exhibit B, and hereinafter
referred to as "Landlord's Work." Landlord will deliver the Premises to Tenant
with all of Landlord's Work substantially completed in a good and workmanlike
manner, in accordance with the Plans and Specifications approved by Tenant
(except for minor and non-material punch list items which will not delay
completion of Tenant's Work, as defined in subparagraph B of this Article), six
(6) months after the full execution date of this Lease (the "Anticipated
Completion Date"), provided, however, that at such time as Landlord delivers the
final Lease to Tenant for its signature and Tenant executes the same and
delivers the partially executed counterparts to Landlord for its signature,
Landlord agrees to execute the same within 5 business days. If Landlord is
delayed in completing Landlord's Work by the Anticipated Completion Date due to
strike, shortages of labor or materials, delays caused by Tenant or other
matters beyond the reasonable control of Landlord, then Landlord shall give
notice thereof to Tenant and the date on which Landlord is to turn the Premises
over to Tenant for Tenant's Work, the Anticipated Completion Date and the Rent
Commencement Date shall be postponed for an equal number of days as the delay as
set forth in the notice. If Landlord does not complete its work by the dates set
forth above, the following shall apply and shall constitute Tenant's sole and
exclusive remedy with respect thereto: (i) for delays of up to thirty (30) days,
the Date of Rent Commencement shall be delayed one day for each day of delay,
(ii) for delays greater than thirty (30) but less than sixty (60) days, two days
for each day of delay, and (iii) for delays of sixty (60) days or greater, in
addition to the provisions of (ii), Tenant shall have the option to terminate
this lease upon 30 days prior notice and be reimbursed for all reasonable
expenditures made in connection herewith provided, however, that if Landlord
substantially completes Landlord's Work within the 30 day period between the
date of Tenant's termination notice and the effective date of termination, then
Tenant's notice of termination shall be null and void. In the event of Tenant
Delay (as defined herein), the Anticipated Completion Date shall be extended for
a number of days equal to the Tenant Delay and it is understood and agreed that
the Rent Commencement Date shall not be changed or otherwise affected under such
circumstance. As used herein, "Tenant Delay" shall mean any demonstrable delay
caused by Tenant that delays the substantial completion of Landlord's Work
beyond the date that Landlord's Work would have been substantially completed but
for such delay.

                  Landlord may, at Landlord's sole responsibility for all costs
associated therewith, by written notification to Tenant, request changes to
Landlord's Work (the "Change Proposal"). Such notification shall be accompanied
by a summary of the additional costs, or savings, involved with the proposed
change, an estimate of the period of time by which the date of substantial
completion of Landlord's Work will be affected by the change and an indication
of impacts, if any, upon Tenant's cost and completion schedule for Tenant's
Work, it being understood that, in no instance shall Tenant be obligated to
approve a Landlord Change Proposal which would either (i) increase the cost of
Tenant's Work (unless Landlord agrees to pay such additional costs) or (ii)
delay the substantial completion of Tenant's Work.

                  B.       Tenant's Work. Tenant, at its sole cost and expense,
shall perform and complete all other improvements to the Premises as more
particularly set forth in the work letter

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attached hereto as Exhibit C (herein called "Tenant's Work") including, but not
limited to, all improvements, work and requirements required of Tenant under the
foregoing work letter. Tenant shall complete all of Tenant's Work in good and
workmanlike manner, fully paid for and free from liens, in accordance with the
plans and specifications approved by Landlord and Tenant as provided in Exhibit
C. Tenant shall also have the right during this period to come onto the Premises
to install its fixtures and prepare the Premises for the operation of Tenant's
business. Tenant, during the course of performing Tenant's Work, shall not
unreasonably interfere with the performance of Landlord's Work. Notwithstanding
the fact that the foregoing activities may occur prior to the Rent Commencement
Date, Tenant agrees that all of Tenant's obligations provided for in this Lease
shall apply during any such period, with the exception of any obligation to pay
Monthly Rent, Operating Expenses or Taxes. Landlord shall provide Tenant with a
Tenant Work Allowance to reimburse Tenant for all or part of the cost of
Tenant's Work as more particularly set forth in Exhibit C.

                  C.       Alterations. Except as provided in the immediately
preceding subparagraph, and except for non-structural and non-Building system
alterations not in excess of Seventy-Five Thousand Dollars ($75,000) in any
Lease Year, Tenant shall make no alterations or additions to the Premises
("Alterations") without the prior written consent of Landlord, which consent may
be withheld in Landlord's reasonable discretion, and then only by contractors or
mechanics approved by Landlord in writing and upon the approval by Landlord in
writing of fully detailed and dimensioned plans and specifications pertaining to
the Alterations in question, to be prepared and submitted by Tenant, at its sole
cost and expense. Tenant shall, at its sole cost and expense, obtain all
necessary approvals and permits pertaining to any Alterations approved by
Landlord. If Landlord, in approving any Alterations, specifies a reasonable
commencement date therefor, Tenant shall not commence any work with respect to
such Alterations prior to such date. Tenant hereby indemnifies, defends and
agrees to hold Landlord free and harmless from all liens and claims of lien, and
all other liability, claims and demands arising out of any work done or material
supplied to the Premises by or at the request of Tenant in connection with any
Alterations. If permitted Alterations are made, they shall be made at Tenant's
sole cost and expense and shall be and become the property of Landlord, except
that Landlord may, provided notice is given to Tenant at the time Landlord
approves such Alteration, require Tenant, at Tenant's expense, to remove all
partitions, counters, railings and other Alterations installed by Tenant, and to
repair any damages to the Premises caused by such removal upon the expiration or
earlier termination of the Term. If Landlord's approval is not required in
connection with an Alteration, Landlord may require removal of such Alteration,
as aforesaid, at any time within thirty (30) days after Tenant's written request
for a determination by Landlord as to whether such Alteration shall be removed
upon the expiration or earlier termination of the Term. Any and all costs
attributable to or related to the applicable building codes of the city in which
the Building is located (or any other authority having jurisdiction over the
Building) arising from Tenant's plans, specifications, improvements, alterations
or otherwise shall be paid by Tenant at its sole cost and expense. With regard
to repairs, Alterations or any other work arising from or related to this
Article 5, Landlord shall be entitled to receive an administrative fee of two
percent (2%). The construction of initial improvements to the Premises shall be
governed by the terms of the Tenant work letter, attached hereto as Exhibit C,
and not the terms of this Article 5.

                  D.       Liens. Tenant shall give Landlord at least ten (10)
days prior written notice (or such additional time as may be necessary under
applicable laws) of the commencement of any Tenant's Work, to afford Landlord
the opportunity to post and record notices of non-responsibility. Tenant will
not cause or permit any mechanic's, materialman's or similar liens or
encumbrances to be filed or exist against the Premises or the Building or
Tenant's interest in this Lease in connection with work done under this Article
or in connection with any other work and Tenant agrees to defend, indemnify and
hold harmless Landlord from and against any such lien or claim or action
thereon, together with costs of suit and reasonable attorneys' fees incurred by
Landlord in connection with any

                                     - 11 -
<PAGE>

such claim or action. Tenant shall remove any such lien or encumbrance by bond
or otherwise within twenty (20) days from the date Landlord sends Tenant written
notice of their existence. If Tenant fails to do so, Landlord may, without being
responsible to investigate the validity or lawfulness of the lien, pay the
amount or take such other action as Landlord deems necessary to remove any such
lien or encumbrance or require that Tenant deposit with Landlord in cash and
lawful money of the United States, one hundred fifty percent (150%) of the
amount of such claim, which sum may be retained by Landlord until such claim
shall have been removed of record or until judgment shall have been rendered on
such claim and such judgment shall have become final, at which time Landlord
shall have the right to apply such deposit in discharge of the judgment on said
claim and any costs, including attorneys' fees incurred by Landlord, and shall
remit the balance thereof to Tenant. The amounts so paid and costs incurred by
Landlord shall be deemed Additional Rent under this Lease and payable in full
upon demand.

                  E.       Compliance with ADA. Notwithstanding anything to the
contrary contained in this Lease, Landlord and Tenant agree that responsibility
for compliance with the Americans With Disabilities Act of 1990, as amended (the
"ADA") shall be allocated as follows: (i) Landlord shall be responsible for
compliance with the provisions of Title III of the ADA for all Common Areas,
including exterior and interior areas of the Building not included within the
Premises or the premises of other tenants; (ii) Landlord shall be responsible
for compliance with the provisions of Title III of the ADA for any construction,
renovations, alterations and repairs made within the Premises if such
construction, renovations, alterations or repairs are made by Landlord, its
employees, agents or contractors, at the direction of Landlord or done pursuant
to plans and specifications prepared or provided by Landlord or Landlord's
architect or space planner; (iii) Tenant shall be responsible for compliance
with the provisions of Title III of the ADA for any construction, renovations,
alterations and repairs made within the Premises if such construction,
renovations, alterations and repairs are made by Tenant, its employees, agents
or contractors, at the direction of Tenant or done pursuant to plans and
specifications prepared or provided by Tenant or Tenant's architect or space
planner.

                                   ARTICLE 6.

                                      USE

                  A.       Use. Tenant shall use the Premises for the purposes
set forth in Article 1(P), above, and for no other purpose whatsoever, subject
to and in compliance with all other provisions of this Lease, including without
limitation the Building's Rules and Regulations attached as Exhibit D hereto,
consistently enforced. Tenant and its invitees shall also have the non-exclusive
right, along with other tenants of the Building and others authorized by
Landlord, to use the Common Areas subject to such reasonable rules and
regulations as Landlord may impose from time to time consistently enforced.
Tenant agrees to comply with all laws and ordinances including, without
limitation, local ordinances with respect to the storage, disposal, and
emanation of noise or odors relating to presence of any animals in the Premises
but the foregoing shall not modify the provisions relating to Tenant's rooftop
noise as set forth in Section 6C. Tenant agrees to indemnify and hold Landlord
harmless from and against all costs, damages, expenses and losses incurred by
Landlord relating to the breach of the foregoing covenant.

                  B.       Restrictions. Tenant shall not at any time use or
occupy, or suffer or permit anyone to use or occupy, the Premises or do or
permit anything to be done in the Premises which: (a) causes injury to persons,
to the Building or its equipment, facilities or systems; (b) impairs the
character, reputation or appearance of the Building as a first class office and
research and development building; (c) materially impairs the proper and
economic maintenance, operation and repair of the Building or its equipment,
facilities or systems; (d) unreasonably interferes with the use of other

                                     - 12 -
<PAGE>

tenants or occupants of the Building; or (e) would invalidate any fire and
extended coverage insurance policy covering the Building and/or the property
located therein. Tenant shall comply with all rules, orders, regulations and
requirements of any organization which sets out standards, requirements or
recommendations commonly referred to by major fire insurance underwriters.
Tenant shall promptly, upon demand, reimburse Landlord for any additional
premium charges for any such insurance policy assessed or increased by reason of
Tenant's failure to comply with the provisions of this Article.

                  C.       Compliance with Laws. Tenant shall, at Tenant's sole
cost and expense, keep and maintain the Premises, its use thereof and its
business in compliance with all governmental laws, ordinances, rules and
regulations now in force or which may hereafter be in force or effect. Tenant
shall comply with all Laws relating to the Premises and Tenant's use or
occupancy thereof, including without limitation, Laws in connection with the
health, safety and building codes, and any permit or license requirements. For
purposes of complying with the Cambridge Noise Control Ordinance, the Building
is divided into five equal parts, with Landlord's "base building" part equal to
one-fifth, and each of the four tenant-occupied floors of the Building equal to
one-fifth each (with partial floors being allocated a pro rata portion of a full
floor part). Each of the five individual parts is allowed to install mechanical
equipment producing a total exterior noise emission level of 53 dBA at any
residential receptor during daytime hours 7AM to 6PM (except Sundays) and 43 dBA
at all other times. Compliance with this provision will be determined by an
acoustical consultant (acceptable to the parties) employing the software
analysis tool, "Cadna/A", or some equivalent, to model the expected noise
emission levels of equipment to predict the resultant sound levels (dBA) at
nearby residential receptor positions. The nearest residential receptors are
located on the top floor of the Building at 265 Binney Street; predictions shall
also be made for a second-floor receptor at the corner of Charles and Third
Streets.

                                   ARTICLE 7.

                                    SERVICES

                  A.       Climate Control. Landlord shall furnish heat or air
conditioning to the Premises during Normal Business Hours of the Building as set
forth in Article 1, for the comfortable use and occupancy of the Premises. If
Tenant requires heat or air conditioning at any other time, Landlord shall
furnish such service upon reasonable notice from Tenant, and Tenant shall pay
all of Landlord's reasonable charges therefor monthly as Additional Rent.

                  The performance by Landlord of its obligations under this
Article is subject to Tenant's compliance with the terms of this Lease including
any connected electrical load established by Landlord. Tenant shall not use the
Premises or any part thereof in a manner exceeding the heating, ventilating or
air-conditioning ("HVAC") design conditions (including any occupancy or
connected electrical load conditions), including the rearrangement of
partitioning which may interfere with the normal operation of the HVAC
equipment.

                  B.       Elevator Service. Landlord shall furnish elevator
service to Tenant to be used in common with others. At least one elevator shall
remain in service during all other hours. Landlord shall designate a specific
elevator for use as a service elevator which Tenant may use, inter alia, in
connection with its animal facility.

                  C.       Janitorial Services. Landlord shall provide
janitorial and cleaning services to the Building, substantially as described in
Exhibit D attached hereto, as an Operating Expense. Tenant shall provide its own
janitorial services to the Premises.

                                     - 13 -
<PAGE>

                  D.       Water and Electricity. Landlord shall make available
domestic water in reasonable quantities to the common areas of the Building (and
to the Premises if so designated in Exhibit B) and cause electric service
sufficient for lighting the Premises and for the operation of Tenant's
equipment. Tenant's use of electric energy or water in the Premises shall not at
any time exceed the capacity of any of the risers, piping, electrical conductors
and other equipment in or serving the Premises unless Landlord grants its
consent in writing, which shall not be unreasonably withheld, conditioned or
delayed, in which event all additional risers, piping and electrical conductors
or other equipment therefor shall be provided by Landlord and the cost thereof
shall be paid by Tenant within 10 days of Landlord's demand therefor. As a
condition to granting such consent, Landlord may require Tenant to agree to an
increase in Monthly Rent to offset the expected cost to Landlord of such
additional service, that is, the cost of the additional electric energy to be
made available to Tenant based upon the estimated additional capacity of such
additional risers, piping and electrical conductors or other equipment. If
Landlord and Tenant cannot agree thereon, such cost shall be determined by an
independent electrical engineer, to be selected by Landlord and paid equally by
both parties.

                  E.       Separate Meters. If the Premises are separately
metered for any utility, Tenant shall pay a utility charge to Landlord (or
directly to the utility company, if possible) based upon Tenant's actual
consumption as measured by the meter. All utilities shall be separately metered
to the extent practicable. Landlord also reserves the right to install separate
meters for the Premises to register the usage of all or any one of the utilities
and in such event Tenant shall pay for the cost of utility usage as metered to
the Premises but shall not be obligated for such utility as an Operating Expense
except as it relates to Common Areas. Tenant shall immediately reimburse
Landlord for the cost of installation of meters, and the maintenance and repair
thereof, if Tenant's actual usage exceeds the anticipated usage level by more
than 10 percent. The term "utility" for purposes hereof may refer to but is not
limited to electricity, gas, water, sewer, steam, fire protection system,
telephone or other communication or alarm service, as well as HVAC, and all
taxes or other charges thereon.

                  F.       Interruptions. Landlord does not represent or warrant
that any of the services referred to above, or any other services which Landlord
may supply, will be free from interruption and Tenant acknowledges that any one
or more of such services may be suspended by reason of accident, repairs,
inspections, alterations or improvements necessary to be made, or by strikes or
lockouts, or by reason of operation of law, or causes beyond the reasonable
control of Landlord. Provided that Landlord exercises reasonable diligence to
restore the same, any interruption, reduction or discontinuance of service shall
not be deemed an eviction or disturbance of Tenant's use and possession of the
Premises, or any part thereof, nor render Landlord liable to Tenant for damages
by abatement of Rent or otherwise, nor relieve Tenant from performance of
Tenant's obligations under this Lease. Landlord acknowledges that the services
referred to above are critical to Tenant's business and shall take all
reasonable measures to prevent their interruption, and if interrupted, to
restore the same promptly. Notwithstanding anything to the contrary contained in
this Lease, Landlord shall have no liability whatsoever for any loss, cost,
damage or expense sustained by Tenant as a result of the failure of Tenant's
experimental trials which arise as a result of the failure or interruption of
Building systems or services, absent any willful misconduct by Landlord.

                  G.       Utilities Provided by Tenant. Tenant shall make
application in Tenant's own name for all utilities not provided by Landlord and
shall: (i) comply with all utility company regulations for such utilities,
including requirements for the installation of meters, and (ii) obtain such
utilities directly from, and pay for the same when due directly to, the
applicable utility company. The term "utilities" for purposes hereof shall
include but not be limited to electricity, gas, water, sewer, steam, fire
protection, telephone and other communication and alarm services, and all taxes
or other charges thereon. Tenant shall install and connect all equipment and
lines required to supply such utilities to the extent not already available at
or serving the Premises, or at Landlord's option shall

                                     - 14 -
<PAGE>

repair, alter or replace any such existing items. Tenant shall maintain, repair
and replace all such items, operate the same, and keep the same in good working
order and condition. Tenant shall not install any equipment or fixtures, or use
the same, so as to exceed the safe and lawful capacity of any utility equipment
or lines serving the same. The installation, alteration, replacement or
connection of any utility equipment and lines shall be subject to the
requirements for alterations of the Premises set forth in Article 5. Tenant
shall ensure that all Tenant's HVAC equipment is installed and operated at all
times in a manner to prevent roof leaks, damage, or noise due to vibrations or
improper installation, maintenance or operation. Except as specifically provided
in this Article 7, Tenant agrees to pay for all utilities and other services
utilized by Tenant and additional Building services furnished to Tenant not
uniformly furnished to all tenants of the Building at the rate generally charged
by Landlord to other tenants of the Building.

                                   ARTICLE 8.

                                    INSURANCE

                  A.       Required Insurance. Tenant shall, at all times during
the Term of this Lease, and at its own cost and expense, maintain insurance
policies, with responsible companies licensed to do business in the state where
the Building is located and satisfactory to Landlord, naming as additional
insureds Landlord, Landlord's Building Manager, Cornerstone Real Estate
Advisers, Inc., Palm, Inc., Tenant and any Mortgagee of Landlord, as their
respective interests may appear, including (i) a policy of standard fire,
extended coverage and special extended coverage ("all risk") property insurance
which shall be primary on the lease improvements referenced in Article 5 and
Tenant's property, including its goods, equipment and inventory, in an amount
adequate to cover their replacement cost, including a vandalism and malicious
mischief endorsement, and sprinkler leakage coverage; (ii) business interruption
insurance, loss of income and extra expense insurance, including coverage for
the failure of Tenant's telecommunications equipment, (iii) commercial general
liability insurance on an occurrence basis with limits of liability in an amount
not less than One Million Dollars ($1,000,000) combined single limit for each
occurrence, and Two Million Dollars ($2,000,000) in the annual aggregate, (iv)
Worker's Compensation Coverage as required by law, (v) contractual liability
insurance, (vi) excess umbrella liability insurance in an amount not less than
Five Million Dollars ($5,000,000.00) each occurrence and Five Million Dollars
($5,000,000.00) annual aggregate. The commercial general liability policy shall
include contractual liability which includes the provisions of Article 9 herein
which, if written on a separate claims-made basis, shall continue for at least a
three year period after the expiration or earlier termination of this Lease.

                  On or before the first date that Tenant enters the Building
for the purpose of performing any work, Tenant shall furnish to Landlord and its
Building Manager, certificates of insurance evidencing the insurance coverage
set forth above, including naming Landlord, Cornerstone Real Estate Advisers,
Inc., Palm, Inc. (or its successors and assigns under its existing lease for
premises in the Building and as the guarantor under a certain "Guaranty"
delivered in connection with this Lease) and Landlord's Building Manager as
additional insureds. Renewal certificates must be furnished to Landlord on or
prior to the expiration date of such insurance policies showing the above
coverage to be in full force and effect.

                  All such insurance policies carried by Tenant shall be with
companies having a rating of not less than A-VIII in Best's Insurance Guide. All
such policies shall be endorsed to agree that Tenant's policy is primary and
that any insurance covered by Landlord is excess, secondary and not contributing
with any Tenant insurance requirement hereunder. Tenant agrees that if Tenant
does not take out and maintain such insurance or furnish Landlord with renewals
or binders, Landlord may (but shall not be required to) procure said insurance
on Tenant's behalf and charge Tenant the reasonable

                                     - 15 -
<PAGE>

cost thereof, which amount shall be payable by Tenant upon demand with interest
from the date such sums are extended. All such insurance shall provide that it
cannot be canceled except upon thirty (30) days prior written notice to
Landlord. Tenant shall comply with all reasonable rules and directives of any
insurance board, company or agency determining rates of hazard coverage for the
Premises, including but not limited to the installation of any equipment and/or
the correction of any condition necessary to prevent any increase in such rates.

                  B.       Landlord's Insurance. Landlord shall maintain, during
the Term of this Lease, property, commercial general liability and, if available
at commercially reasonable rates, pollution liability insurance covering the
Building. The property insurance shall include fire and extended coverage
insurance, with All Risk rider, covering all structures and improvements for
full replacement value, with replacement cost endorsement, above foundation
walls. The commercial general liability insurance shall insure against claims
for bodily injury and property damage occurring in or about the Property. Such
insurance may be blanketed with other insurance carried by Landlord so long as
such blanketing with other insurance does not reduce the amount of insurance
available to pay any claim with respect to the Property. Tenant shall pay its
Pro Rata Share of Landlord's insurance as an Operating Expense.

                  C.       Waiver of Subrogation. Landlord and Tenant each agree
that neither Landlord nor Tenant will have any claim against the other for any
loss, damage or injury which is covered by insurance carried by either party and
for which recovery from such insurer is made, notwithstanding the negligence of
either party in causing the loss, and each agree to have their respective
insurers issuing the insurance described in this Article 8 waive any rights of
subrogation that such companies may have against the other party. This release
shall be valid only if the insurance policy in question permits waiver of
subrogation or if the insurer agrees in writing that such waiver of subrogation
will not affect coverage under said policy. Each party agrees to use
commercially reasonable efforts to obtain such an agreement from its insurer if
the policy does not expressly permit a waiver of subrogation.

                  D.       Waiver of Claims. To the extent covered by Tenant's
insurance required hereunder, Tenant waives all claims against Landlord for
injury or death to persons, damage to property or to any other interest of
Tenant sustained by Tenant or any party claiming, through Tenant resulting from:
(i) any occurrence in or upon the Premises, (ii) leaking of roofs, bursting,
stoppage or leaking of water, gas, sewer or steam pipes or equipment, including
sprinklers, (iii) wind, rain, snow, ice, flooding, freezing, fire, explosion,
earthquake, excessive heat or cold, or other casualty, (iv) the Building,
Premises, or the operating and mechanical systems or equipment of the Building,
being defective, or failing, and (v) vandalism, malicious mischief, theft or
other acts or omissions of any other parties including, without limitation,
other tenants, contractors and invitees at the Building. Notwithstanding
anything in this Lease to the contrary, in no event will Landlord and Tenant be
responsible for any consequential damages incurred by the other, including but
not limited to, lost profits or interruption of business as a result of any
alleged default by the other under this Lease.

                                   ARTICLE 9.

                                 INDEMNIFICATION

                  A.       Tenant Indemnity of Landlord. Tenant shall defend,
indemnify and hold harmless Landlord and its agents, successors and assigns,
including its Building Manager, from and against any and all injury, loss,
costs, expenses, liabilities, claims or damage (including attorneys' fees and
disbursements) to any person or property (i) arising from, related to, or in
connection with any use or occupancy of the Premises by Tenant, (ii) arising
from, related to, or in connection with any act or

                                     - 16 -
<PAGE>

omission (including, without limitation, construction and repair of the Premises
arising out of Tenant's Work or subsequent work) of Tenant, its agents,
contractors, employees, customers, and invitees, or (iii) which occurs in any
part of the Property other than the Premises and is caused by the negligence or
willful misconduct of Tenant, which indemnity extends to any and all claims
arising from any breach or default in the performance of any obligation on
Tenant's part to be performed under the terms of this Lease. This
indemnification shall survive the expiration or termination of the Lease Term.

                  B.       Landlord Indemnity of Tenant. Landlord shall defend,
indemnify and hold Tenant harmless from and against all claims, causes of
action, liabilities, losses, costs and expenses arising from or in connection
with any injury or other damage to any person or property resulting from the
gross negligence or willful misconduct of Landlord, its agents, contractors,
employees, customers and invitees.

                  C.       Indemnity Limitations. The indemnity obligations set
forth in sections A and B above shall not apply (i) to any costs or expenses not
reasonably incurred by the indemnitee, or (ii) to any claims, causes of action,
liabilities, losses, costs and expenses resulting from a default by the
indemnitee hereunder. This lease and each and every provision hereof is subject
to the provisions of Massachusetts General Laws, Chapter 186, Section 15, as the
same may from time to time be in force and applicable, and wherever any
provision herein might be construed to violate said statute, such provision
shall be construed as though it included the words "subject and to the extent
enforceable in accordance with the provisions of Massachusetts General Laws,
Chapter 186, Section 15."

                  D.       Indemnitees; Acceptable Attorneys. Whenever, in this
Article and throughout this Lease, Landlord or Tenant is required to defend,
indemnify and hold the other harmless, such obligations shall extend to the
successors, assigns, officers, partners, directors, employees and other agents
of the indemnitee. In any instance where this Lease requires either party to
defend the other, such defense shall involve an attorney or attorneys reasonably
acceptable to the indemnitee.

                  E.       Limitation on Liability. Landlord shall not be liable
to Tenant for any damage by or from any act or negligence of any co-tenant or
other occupant of the Building, or by any owner or occupants of adjoining or
contiguous property. Landlord shall not be liable for any injury or damage to
persons or property resulting in whole or in part from the criminal activities
or willful misconduct of others. To the extent not covered by all risk property
insurance, Tenant agrees to pay for all damage to the Building, as well as all
damage to persons or property of other tenants or occupants thereof, caused by
the negligence, willful misconduct of Tenant or any of its agents, contractors,
employees, customers and invitees. Nothing contained herein shall be construed
to relieve Landlord from liability for any personal injury resulting from its
gross negligence or willful misconduct.

                  F.       Surveillance. Tenant acknowledges that Landlord's
election to provide mechanical surveillance or to post security personnel in the
Building is subject to Landlord's sole discretion. Landlord shall have no
liability in connection with the decision whether or not to provide such
services and Tenant hereby waives all claims based thereon. Landlord shall not
be liable for losses due to theft, vandalism, or like causes. Tenant shall
defend, indemnify, and hold Landlord harmless from any such claims made by any
employee, licensee, invitee, contractor, agent or, other person whose presence
in, on or about the Premises or the Property is attendant to the business of
Tenant.

                                     - 17 -
<PAGE>

                                   ARTICLE 10.

                                 CASUALTY DAMAGE

                  Tenant shall promptly notify Landlord or the Building Manager
of any fire or other casualty to the Premises or to the extent it knows of
damage, to the Building. In the event the Premises or any substantial part of
the Building is wholly or partially damaged or destroyed by fire or other
casualty which is covered by Landlord's insurance, Landlord will proceed
promptly to restore the same to substantially the same condition existing
immediately prior to such damage or destruction to the extent of insurance
proceeds collected and made available by any mortgagee of Landlord unless, in
Landlord's sole judgment, (i) such damage or destruction is incapable of repair
or restoration within one hundred eighty (180) days; or (ii) the insurance
proceeds recovered by reason of the damage or destruction are, in Landlord's
sole judgment, inadequate to complete the restoration of the Building; or (iii)
any mortgagee of Landlord shall fail to make insurance proceeds available for
restoration, in any of which events Landlord may, at Landlord's option and by
written notice given to Tenant within sixty (60) days after such damage or
destruction, declare this Lease terminated as of the happening of such damage or
destruction without further recourse to either party. If, in Landlord's sole
judgment, the net insurance proceeds recoverable by reason of the damage or
destruction and made available by any mortgagee of Landlord will not be adequate
to complete the restoration of the Building, Landlord shall have the right to
terminate this Lease and all unaccrued obligations of the parties hereto by
sending a notice of such termination to Tenant. To the extent after fire or
other casualty that Tenant shall be deprived of the use and occupancy of the
Premises or any portion thereof as a result of any such damage, destruction or
the repair thereof, Tenant shall be relieved of the same ratable portion of the
Monthly Rent and other charges due under this Lease as the amount of damaged or
useless space in the Premises bears to the rentable square footage of the
Premises until such time as the Premises are restored.

                                   ARTICLE 11.

                                  CONDEMNATION

                  In the event of a condemnation or taking of the entire or
substantially all of the Premises by a public or quasi-public authority, this
Lease shall terminate as of the date title vests in the public or quasi-public
authority. In the event of a taking or condemnation of fifteen percent (15%) or
more (but less than the whole) of the Building and without regard to whether the
Premises are part of such taking or condemnation, Landlord or Tenant may elect
to terminate this Lease by giving notice to the other within sixty (60) days of
receiving notice of such condemnation. In the event of a partial taking as
described in this Article, or a sale, transfer or conveyance in lieu thereof,
which does not result in the termination of this Lease, Rent shall be
apportioned according to the ratio that the part of the Premises remaining
usable by Tenant bears to the total area of the Premises and other equitable
factors bearing on the Fair Rental Value of the Premises. All compensation
awarded for any condemnation shall be the property of Landlord, whether such
damages shall be awarded as a compensation for diminution in the value of the
leasehold or to the fee of the Premises, and Tenant hereby assigns to Landlord
all of Tenant's right, title and interest in and to any and all such
compensation except that relating to Tenant Improvements paid for by Tenant and
not reimbursed by Landlord. Providing, however that in the event this Lease is
terminated, Tenant shall be entitled to make a separate claim for costs of
relocation of its Tenant Improvements and moving. Notwithstanding anything
herein to the contrary, any condemnation award to Tenant shall be available only
to the extent such award is payable separately to Tenant and does not diminish
the award available to Landlord or any Lender of Landlord. Any additional
portion of such award shall belong to Landlord. Except as provided in this
Article 11, Tenant hereby waives any and all rights, imposed

                                     - 18 -
<PAGE>

by law, statute, ordinance, governmental regulation or requirement of the United
States, the State in which the Building is located or any local government
authority or agency or any political subdivision thereof, now or hereafter in
effect, it might otherwise have to petition a court to terminate the Lease.

                                   ARTICLE 12.

                             REPAIR AND MAINTENANCE

                  A.       Tenant's Obligations. Tenant shall keep the Premises
in good working order, repair (and in compliance with all Laws now or hereafter
adopted) and condition (which condition shall be neat, clean and sanitary, and
free of pests) and shall make all necessary non-structural repairs thereto and
any repairs to non-Building standard mechanical, HVAC, electrical and plumbing
systems or components in or serving the Premises. Tenant's obligations hereunder
shall include, but not be limited to, Tenant's trade fixtures and equipment,
security systems, signs, interior decorations, floor-coverings, wall-coverings,
entry and interior doors, interior glass, light fixtures and bulbs, keys and
locks, and alterations to the Premises whether installed by Tenant or Landlord.
Landlord may make any urgently required repairs which are not promptly made by
Tenant after Tenant's receipt of written notice and the reasonable opportunity
of Tenant to make said repair within five (5) business days from receipt of said
written notice, and charge Tenant for the cost thereof, which cost shall be paid
by Tenant within five (5) days from invoice from Landlord. Tenant waives all
rights to deduct the cost of Landlord's Obligations from Rent.

                  B.       Landlord's Obligations. Landlord shall maintain (i)
the foundations, roof, perimeter walls and exterior windows and all structural
aspects of the Building, and (ii) all nonstructural aspects of the Building
which relate to the Common Areas or to more than one tenant's premises, or which
no tenant of the Building is required to maintain and repair, including all
systems and facilities necessary for the operation of the Building and the
provision of services and utilities as required herein (except to the extent
that any of the foregoing items are installed by or on behalf of, or are the
property of, Tenant). Landlord shall also make all necessary structural repairs
to the Building and any necessary repairs to the Building standard mechanical,
HVAC, electrical, and plumbing systems in or servicing the Premises (the cost of
which shall be included in Operating Expenses under Article 4), excluding
repairs required to be made by Tenant pursuant to this Article. Landlord shall
have no responsibility to make any repairs unless and until Landlord receives
written notice of the need for such repair or otherwise becomes aware. Landlord
shall not be liable for any failure to make repairs or to perform any
maintenance unless such failure shall persist for an unreasonable period of time
after written notice of the need for such repairs or maintenance is received by
Landlord from Tenant or after Landlord otherwise becomes aware. Landlord shall
make every reasonable effort to perform all such repairs or maintenance in such
a manner (in its judgment) so as to cause minimum interference with Tenant and
the Premises but Landlord shall not be liable to Tenant for any interruption or
loss of business pertaining to such activities. Landlord shall have the right to
require that any damage caused by the willful misconduct of Tenant or any of
Tenant's agents, contractors, employees, invitees or customers, be paid for and
performed by the Tenant (without limiting Landlord's other remedies herein).
Tenant shall have the right of self-help if Landlord fails to fulfill its
obligations pursuant to the terms of this Lease.

                  C.       General Obligations. Alterations to the Premises
required from time to time to comply with applicable laws, requirements of any
board of property insurance underwriters or similar entity, or reasonable
requirements of Landlord's or Tenant's insurers shall be made by the party to
this Lease responsible for maintaining and repairing the applicable aspect of
the Premises hereunder. Notwithstanding the foregoing, in the event that
Landlord is required to make any such alteration as a result of any use of the
Premises by Tenant which was not contemplated at the time this

                                     - 19 -
<PAGE>

Lease was signed, Tenant shall reimburse Landlord upon demand for all expenses
reasonably incurred by Landlord in connection therewith. Landlord warrants to
Tenant that, as of the Rent Commencement Date, all aspects of the Premises
comprising Landlord's Work, if any, shall comply with all applicable laws, with
the requirements of Landlord's insurers, and with the requirements of all boards
of property insurance underwriters and similar entities.

                  D.       Obstructions. Tenant shall not obstruct or permit the
obstruction of light, halls, Common Areas, roofs, parapets, stairways or
entrances to the Building or the Premises and will not affix, paint, erect or
inscribe any sign, projection, awning, signal or advertisement of any kind to
any part of the Building or the Premises, including the inside or outside of the
windows or doors, without the written, reasonable consent of Landlord. Landlord
shall have the right to reasonably withdraw such consent at any time and to
require Tenant to remove any sign, projection, awning, signal or advertisement
to be affixed to the Building or the Premises if such sign, etc. is later
determined to obstruct the foregoing areas. If such work is done by Tenant
through any person, firm or corporation not designated by Landlord, or without
the express written consent of Landlord, Landlord shall have the right to remove
such signs, projections, awnings, signals or advertisements without being liable
to the Tenant by reason thereof and to charge the cost of such removal to Tenant
as Additional Rent, payable within ten (10) days of Landlord's demand therefor.

                  E.       Signs. If and so long as the Tenant shall lease and
occupy at least one full floor of the Building, Tenant shall have the right,
subject to the terms of this Paragraph and the other terms of this Lease, to
place and maintain one exterior, building-mounted sign on the Building facade,
at the so-called "eyebrow" location as shown on Exhibit F attached hereto. All
signage rights granted hereunder are limited by taking into account
proportionate signage rights granted or allocated to other premises in the
Building, are non-exclusive and, without in any way limiting the generality of
the foregoing, Landlord reserves the right to grant signage rights to other
tenants in the Building. Notwithstanding the foregoing, (1) Tenant shall be
entitled to have the largest, most prominent exterior sign (as compared to all
other tenants in the Building) for so long as Tenant leases the largest amount
of space in the Building and (2) Landlord shall only grant exterior signage
rights to other tenants in the Building that lease at least one full floor.

         The size, construction and design of Tenant's sign shall be by mutual
agreement of the parties, provided that Landlord may refuse to approve any sign
that is not consistent with the architecture and general appearance of the
Building, will cause undue damage to the Building or which is otherwise
inconsistent with first-class office building signage. Tenant's sign shall be
expressly for purposes of identifying Tenant and shall not include the name of
any other person or entity. Tenant shall obtain, at its expense, all permits and
approvals required for the installation of Tenant's sign prior to the
installation thereof (but shall not be permitted to seek any zoning or similar
relief for Tenant's Sign without Landlord's consent, which may be withheld in
Landlord's reasonable discretion), and shall keep all such permits and approvals
in full force and effect throughout the Term. The installation and maintenance
of Tenant's sign shall also conform to the requirements of Landlord's insurance
policies.

         The installation of Tenant's sign shall be undertaken by a contractor
approved by Landlord and at Tenant's sole cost and expense. Prior to the
expiration or earlier termination of the Term of this Lease, or upon Tenant
ceasing to lease and occupy at least one full floor of the Building, Tenant
shall remove Tenant's sign (and all associated hardware) from the Building and
shall fill all holes and repair all damage caused by such removal. Such removal
(and any disposal of Tenant's sign) shall be undertaken by a contractor approved
by Landlord and at Tenant's sole cost and expense. In the event Tenant fails to
remove Tenant's sign as herein required, Tenant hereby authorizes Landlord to
remove and dispose of Tenant's sign at Tenant's sole cost and expense.

                                     - 20 -
<PAGE>

         All repairs to Tenant's sign and all maintenance of Tenant's sign shall
be performed at Tenant's sole cost and expense. At Landlord's election, Tenant
shall either contract directly for the repair and/or maintenance of Tenant's
sign with such contractor(s) as Landlord shall approve or Landlord shall repair
and/or maintain Tenant's sign as part of Landlord's overall repair and
maintenance of the Building, in which case Tenant shall pay Landlord, as
Additional Rent, any and all the reasonable costs incurred by Landlord in
connection therewith promptly upon demand. If Tenant's sign is electrified,
Tenant shall also pay Landlord, as Additional Rent, the cost of all electricity
consumed in the operation of Tenant's sign, as separately metered or sub-metered
to Tenant or as reasonably estimated by Landlord and billed to Tenant. Tenant
acknowledges that Tenant's sign shall be at Tenant's risk and that Landlord is
under no obligation to insure Tenant's sign against casualty loss or damage. In
the event Tenant's sign is damaged, Landlord may remove and dispose of Tenant's
sign at Tenant's cost unless Tenant arranges for the repair of Tenant's sign by
a contractor approved by Landlord promptly following such casualty.

         Notwithstanding any other provision of this Lease, Tenant's right to
install and maintain Tenant's Sign shall not be assignable to any party other
than assignees and subtenants in occupancy permitted hereunder.

         Tenant shall also have the right to install, at its sole cost and
expense, appropriate signage at the entry to the Premises, provided that the
design, location and size of said signage shall be subject to the approval of
Landlord, not to be unreasonably withheld, and that Tenant shall remove all such
signage and repair any damage caused by such removal upon the expiration or
earlier termination of the Lease.

         At no additional cost to Tenant, Landlord shall provide a building
directory in the lobby of the Building indicating Tenant's name and the location
of the Premises.

                  F.       Outside Services. Tenant shall not permit, except by
Landlord or a person or company reasonably satisfactory to and approved by
Landlord: (i) the extermination of vermin in, on or about the Premises; (ii) the
servicing of heating, ventilating and air conditioning equipment; (iii) the
collection of rubbish and trash other than in compliance with local government
health requirements and in accordance with the rules and regulations established
by Landlord, which shall minimally provide that Tenant's rubbish and trash shall
be kept in containers located so as not to be visible to members of the public
and in a sanitary and neat condition; or (iv) window cleaning, janitorial
services or similar work in or about the Premises.

                  G.       Condition of Premises. Landlord shall deliver the
Premises and Landlord's Work shall be good and workmanlike using first class
materials. Landlord's Work is hereby warranted for one year from the Rent
Commencement Date and no costs to effect the same shall be included in Operating
Expenses. All Building systems including, but not limited to, HVAC, mechanical
and electrical, elevators and the structure of the Building shall be in good
working order and/or good repair, as the case may be, at the time Tenant
occupies the Premises. The Premises shall be initially improved as provided in,
and subject to, the Tenant Work Letter attached hereto as Exhibit "B" and made a
part hereof. The existing leasehold improvements in the Premises as of the date
of this Lease, together with the Tenant Improvements (as defined in the Tenant
Work Letter) may be collectively referred to herein as the "Tenant
Improvements."

                  Landlord reserves the right from time to time, but subject to
payment by and/or reimbursement from Tenant as otherwise provided herein: (i) to
install, use, maintain, repair, replace and relocate for service to the Premises
and/or other parts of the Building pipes, ducts, conduits, wires, appurtenant
fixtures, and mechanical systems, wherever located in the Premises or the
Building, (ii) to

                                     - 21 -
<PAGE>

alter, close or relocate any facility in the Premises or the Common Areas or
otherwise conduct any of the above activities for the purpose of complying with
legal requirements for fire/life safety for the Building or otherwise and (iii)
to comply with any federal, state or local law, rule or order with respect
thereto or the regulation thereof not currently in effect. Landlord shall use
reasonable efforts to perform any such work with the least inconvenience to
Tenant as possible, but in no event shall Tenant be permitted to withhold or
reduce Rent or other charges due hereunder as a result of same or otherwise make
claim against Landlord for interruption or interference with Tenant's business
and/or operations. No incursion into or through the Premises shall be made
without Tenant's consent except in the case of an emergency. Notwithstanding the
foregoing, in the event Landlord requires entry into the Premises for the
purpose of performing any of its obligations contained in this Lease and such
entry is denied, Landlord shall not be deemed in default hereunder for failing
to perform such obligations.

                  H.       Communications and Other Equipment. Subject to
obtaining Landlord's reasonable consent, Tenant, at no additional Rent or other
charge, shall have the right to install satellite transmission and receiving
dishes, antennas and devices, HVAC and plumbing vents and other equipment
(collectively, "Tenant's Roof Equipment") from the Premises through the Building
and to and on the roof of the Building provided (a) Tenant complies with all
local, state and federal laws pertaining to the installation, maintenance,
operation, removal and replacement of any of Tenant's Roof Equipment, (b) Tenant
does not do any act which would invalidate any roof warranty or guaranty which
now or hereafter relates to the roof of the Building provided, however, that if
Tenant retains Landlord's roofing contractor to do said act, then Tenant will be
deemed to be in compliance with this covenant, (c) Tenant obtains Landlord's
prior written consent as to the amount of area required, and size, general
aesthetics and location of Tenant's Roof Equipment, (d) Tenant obtains all
required operating permits and approvals from any governmental entity with
jurisdiction over such activities with Landlord's cooperation, (e) Tenant, at
its sole cost and expense, shall pay for all utility costs in connection
therewith and maintain the Tenant's Roof Equipment and adequate insurance
thereon, (f) in the event of any damage caused to the Building (including,
without limitation, the roof or any exterior portions thereof) by reason of the
installation, maintenance, operation, removal or replacement of any of Tenant's
Roof Equipment, Tenant shall, at Landlord's option (1) promptly repair such
damage; or (2) promptly reimburse Landlord for costs and expenses incurred by
Landlord in repairing such damage; (g) Tenant shall use such contractors and
observe such requirements as required by Landlord, and (h) Tenant shall remove
Tenant's Roof Equipment upon the expiration or sooner termination of the Term of
this Lease, and (i) in the event of any resulting damage to the Building
(including, without limitation the roof or any exterior portions thereof) Tenant
shall, at Landlord's option (1) promptly repair such damage and restore the
Building (including, without limitation, the roof or any exterior portions
thereof) substantially to the condition which existed prior to any such
installation, ordinary wear and tear excepted; or (2) promptly reimburse
Landlord for costs and expenses incurred by Landlord in repairing such damage
and making such restoration. The provisions of this Section shall survive the
termination of this Lease. Landlord hereby approves the location of the
emergency generator and supplemental HVAC systems in the locations shown on
Exhibit A attached hereto and made part hereof.

                                   ARTICLE 13.

                             INSPECTION OF PREMISES

                  Subject to Tenant's reasonable security procedures, Tenant
shall permit the Landlord, the Building Manager and its authorized
representatives to enter the Premises to show the Premises during Normal
Business Hours of the Building and at other reasonable times on prior notice to
Tenant or, in the case of an emergency or to inspect the Premises, to clean the
Premises, to serve or post

                                     - 22 -
<PAGE>

notices as provided by law or which are required for the protection of Landlord
or Landlord's property, and to make such repairs, improvements, alterations or
additions in the Premises or in the Building of which they are a part as
Landlord may deem necessary or appropriate. If Tenant shall not be personally
present to open and permit an entry into the Premises at any time when such an
entry is necessary or permitted hereunder, Landlord may enter by means of a
master key or may enter forcibly, only in the case of an emergency, without
liability to Tenant and without affecting this Lease.

                                   ARTICLE 14.

                              SURRENDER OF PREMISES

                  Upon the expiration of the Term, or sooner termination of the
Lease, Tenant shall quit and surrender to Landlord the Premises, broom clean, in
good order and condition, normal wear and tear and damage by fire and other
casualty excepted. All Tenant Improvements and other fixtures, such as light
fixtures and HVAC equipment, wall coverings, carpeting and drapes, in or serving
the Premises, whether installed by Tenant or Landlord, but not Tenant's
equipment or personalty shall be Landlord's property and shall remain, all
without compensation, allowance or credit to Tenant. Any property not removed
shall be deemed to have been abandoned by Tenant and may be retained or disposed
of by Landlord at Tenant's expense free of any and all claims of Tenant, as
Landlord shall desire. All property not removed from the Premises by Tenant may
be handled or stored by Landlord at Tenant's expense and Landlord shall not be
liable for the value, preservation or safekeeping thereof. At Landlord's option
all or part of such property may be conclusively deemed to have been conveyed by
Tenant to Landlord as if by bill of sale without payment by Landlord.

                                   ARTICLE 15.

                                  HOLDING OVER

                  Should Tenant, without Landlord's written consent, hold over
after expiration or termination of this Lease, Tenant shall become a tenant at
sufferance, only upon each and all of the terms herein provided as may be
applicable to a tenant at sufferance and any such holding over shall not
constitute an extension of this Lease. Tenant shall pay Landlord, monthly and in
advance, 150% of the annual Rent that was payable immediately preceding the
hold-over period, escalating 10% per month (i.e., 160% during the 2nd holdover
month, 170% during the 3rd holdover month, etc.), prorated on a per diem basis,
for each day Tenant shall retain possession of the Premises or any part thereof
after expiration or earlier termination of this Lease. Tenant shall never be
liable for consequential, special or other damages and shall be liable only for
direct damages suffered or incurred by Landlord which direct damages shall
include, but not be limited to, damages suffered or incurred in connection with
any reletting of the Premises. The foregoing provisions shall not serve as
permission for Tenant to hold-over, nor serve to extend the Term (although
Tenant shall remain bound to comply with all provisions of this Lease until
Tenant vacates the Premises) and Landlord shall have the right at any time
thereafter to enter and possess the Premises and remove all property and persons
therefrom or to require Tenant to surrender possession of the Premises as
provided in this Lease upon the expiration or earlier termination of the Term.
If Tenant fails to surrender the Premises upon the expiration or termination of
this Lease, Tenant agrees to indemnify, defend and hold harmless Landlord from
all costs, loss, expense or liability, including without limitation, claims made
by any succeeding tenant and real estate brokers' claims and attorneys' fees,
except as provided above with respect to damages other than direct damages. No
acceptance by Landlord of any Rent during or for any period following the
expiration or termination of the Lease shall operate or be construed as an
extension or renewal of the Lease. Should Tenant remain in the Premises on a
month-to-month basis with Landlord's

                                     - 23 -
<PAGE>

approval, such month-to-month tenancy may be cancelled by either party with
thirty (30) days' prior written notice or such lesser time period as may be
permitted by law.

                                   ARTICLE 16.

                            SUBLETTING AND ASSIGNMENT

                  A.       Landlord's Consent. Tenant shall not assign its
interests hereunder, sublease all or any portion of the Premises (for purposes
of this Lease, a license shall be deemed to be a sublease), or list the Premises
or any part thereof as available for assignment or sublease with any broker or
agent or otherwise advertise, post, communicate or solicit prospective assignees
or subtenants through any direct or indirect means, or allow any other person to
use or occupy any portion of the Premises, without the prior written consent of
Landlord, which shall not be unreasonably withheld, conditioned or delayed.
Without limiting the generality of the foregoing, it shall be reasonable for
Landlord to deny consent if:

                           (a)      Intentionally Omitted.

                           (b)      The proposed assignee or subtenant will
         burden the Premises and/or Common Areas to an extent substantially
         disproportionate to Tenant, whether through disproportionate,
         unreimbursed demand for landlord services or utilities,
         disproportionate bearing weights on floor areas, disproportionate
         parking requirements, deterioration of floors or other elements of the
         Building, or otherwise.

                           (c)      The proposed assignee or subtenant intends
         to make substantial alterations to the Premises which would result in a
         material net decrease in the value of the Premises as improved.

                           (d)      The proposed assignee's or subtenant's use
         of the Premises if different than Tenant's will not, in Landlord's
         reasonable judgment, be compatible with the uses of the other tenants
         in the Building or be appropriate for a Class A office building.

                           (e)      The use to be made of the Premises by the
         proposed transferee is a use which would be prohibited by any other
         portion of this Lease (including, but not limited to, any reasonable
         rules and regulations then in effect).

                           (f)      The proposed transferee is either a
         governmental agency or instrumentality thereof.

                           (g)      Either the proposed transferee or any person
         or entity which directly or indirectly controls, is controlled by or is
         under common control with the proposed transferee is negotiating with
         Landlord or has negotiated with Landlord during the six (6) month
         period immediately preceding the date of the proposed transfer, to
         lease space in the Building.

With respect to any proposed assignment or subleasing requiring Landlord's
consent, Tenant shall submit to Landlord in writing, at least 30 days prior to
the effective date of the assignment or sublease, (i) a notice of application to
assign or sublease, setting forth the proposed effective date, which shall be
not less than 30 or more than 90 days after the delivery of such notice; (ii)
the name of the proposed transferee; (iii) the nature of the proposed
transferee's business to be carried on in the Premises; (iv) the terms of the
proposed sublease or assignment; and (v) a current financial statement of the

                                     - 24 -
<PAGE>

proposed transferee. Tenant shall not submit any such application to Landlord
until Tenant has received a bona fide offer from the proposed transferee, and
Tenant shall furnish Landlord, in addition to the foregoing, with all other
information reasonably required by Landlord with respect to such transfer and
transferee including, without limitation, a copy of the proposed sublease, if
available. Any transfer (or sequence of transfers resulting, in the aggregate,
in the transfer) of 50% or more of the beneficial ownership of Tenant (other
than the transfers described in subsection B. below) shall constitute an
assignment for purposes of this Article.

         Landlord may elect, if Tenant is in default beyond applicable notice
and cure period(s), to require that any permitted sublessee including, without
limitation, a sublessee not requiring Landlord's consent, pay Rent to which
Landlord is entitled under this Lease directly to Landlord. Any permitted
assignee hereunder shall be required to pay Rent due hereunder directly to
Landlord at all times.

                  B.       Transfers Not Requiring Consent. Notwithstanding the
foregoing, Landlord's consent shall not be required with respect to (i) any
assignment resulting from a consolidation, merger or purchase of all or
substantially all of Tenant's stock or assets; or (ii) any assignment or
sublease to a person or entity (a) who or which controls Tenant or who or which
controls the person or entity who or which controls Tenant (in either case, a
"Parent"), or who is controlled by Tenant or a Parent, or is controlled by a
person or entity who or which is controlled by Tenant or a Parent, and (b) whose
net worth is not materially less than Tenant's net worth at the time this Lease
was executed. The term "control," as used in this Article 16(B), shall mean the
ownership, directly or indirectly, of more than fifty-one percent (51%) of the
outstanding voting stock of a corporation or other equity interest if Tenant is
not a corporation. With respect to any assignment or subletting to which
Landlord's consent is not required, the following provisions shall apply:

                                    (a)      If permitted by law, Tenant shall
                  give Landlord written notice of the assignment or subletting
                  no less than 30 days prior to the effective date thereof,
                  which notice shall set forth the identity of the proposed
                  transferee, the reason(s) why Landlord's consent is not
                  required, and the nature of the proposed transferee's business
                  to be carried on in the Premises.

                                    (b)      Tenant shall furnish Landlord (i)
                  no less than 30 days prior to the effective date of the
                  assignment or subletting, with a current financial statement
                  of the proposed transferee.

                                    (c)      Tenant shall furnish Landlord with
                  a complete copy of the fully executed assignment and
                  assumption agreement or sublease within ten (10) days after
                  the date said document is executed.

Any assignment or subletting to which Landlord's consent is not required and
with respect to which the provisions of this paragraph are not complied with
shall, at Landlord's option, be void.

                  C.       Recapture. Except for transfers under Article 16(B)
above, Landlord shall notify Tenant within thirty (30) days from the submission
of the aforesaid information as to Landlord's choice, at Landlord's sole
discretion, of the following options:

                                    (1)      That Landlord consents to a
                  subleasing of the Premises or assignment of the Lease to such
                  replacement tenant provided that Tenant shall remain fully
                  liable for all of its obligations and liabilities under this
                  Lease and provided further that Landlord shall be entitled to
                  fifty percent (50%) of any Excess Income, hereinafter defined,
                  obtained by Tenant from such subletting or assignment; or

                                     - 25 -
<PAGE>

                                    (2)      That upon such replacement tenant's
                  entering into a mutually satisfactory new lease for the
                  Premises with Landlord, then Tenant shall be released from all
                  further obligations and liabilities under this Lease
                  (excepting only any unpaid rentals or any unperformed
                  covenants then past due under this Lease or any guarantee by
                  Tenant of replacement tenant's obligations); or

                                    (3)      That Landlord declines to consent
                  to such sublease or assignment pursuant to the express
                  provisions of this Article 16, such notice to specify
                  precisely the reasons for such refusal of consent; or

                                    (4)      Provided Tenant proposes to assign
                  this Lease or sublease more than 66 percent of the Premises,
                  that Landlord elects to cancel the Lease and recapture the
                  Premises (in the case of an assignment) or that Landlord
                  elects to cancel the Lease as to the portion thereof that
                  Tenant had wished to sublease. In either such event Tenant
                  shall surrender possession of the Premises, or the portion
                  thereof which is the subject of Tenant's request on the date
                  set forth in a notice from Landlord in accordance with the
                  provisions of this Lease relating to the surrender of the
                  Premises. If this Lease shall be canceled as to a portion of
                  the Premises only, the Rent payable by Tenant hereunder shall
                  be abated proportionately according to the ratio that the area
                  of the portion of the Premises surrendered bears to the area
                  of the Premises immediately prior to such surrender. If
                  Landlord shall cancel this Lease, Landlord may relet the
                  Premises, or the applicable portion of the Premises, to any
                  other party (including, without limitation, the proposed
                  assignee or subtenant of Tenant), without any liability to
                  Tenant.

                  D.       Excess Income.

                  If the rent and other sums (including, without limitation, all
monetary payments plus the reasonable value of any services performed or any
other thing of value given by any assignee or subtenant in consideration of such
assignment or sublease), either initially or over the term of any assignment or
sublease, payable by such assignee or subtenant, other than a transferee
pursuant to Article 16(B), on account of an assignment of this Lease or sublease
of all or any portion of the Premises exceed the sum of (a) the Rent called for
hereunder with respect to the space assigned or sublet, plus (b) Tenant's
Transfer Expenses (hereinafter defined), then Tenant shall pay to Landlord, as
Additional Rent, 50 percent of any such excess (the "Excess Income").

                  Tenant's Transfer Expenses shall be limited to the following
expenses, and shall be considered in computing the amount of Excess Income only
to the extent they are reasonable and are actually paid by Tenant in connection
with an assignment or sublease consented to by Landlord: (i) the cost, including
architectural and engineering fees, of alterations or improvements made by
Tenant to the Premises in order to consummate an assignment or to the subleased
Premises in order to consummate a sublease, including fees for design or
engineering services, amortized on a straight line basis over the term of the
assignment or sublease, (ii) advertising costs, (iii) brokerage commissions or
fees, and (iv) attorneys fees. Any such costs paid by Tenant shall be verified
by written documentation in form, scope and substance reasonably satisfactory to
Landlord within thirty (30) days after the date of delivery of possession to the
assignee or sublessee or they shall be disregarded in computing Excess Income.

         Excess Income shall be payable monthly at the time for payment of
Monthly Rent. Landlord's acceptance of any sums pursuant to this paragraph shall
not be deemed a granting of consent to any assignment of the Lease or sublease
of all or any portion of the Premises.

                                     - 26 -
<PAGE>

                  E.       Continuing Liability; Voidable Transfers. No
assignment of this Lease (other than an assignment to Landlord resulting from
Landlord's right of recapture), and no subletting of all or any portion of the
Premises, shall release Tenant or any guarantor with respect to any
post-transfer obligations, unless Landlord agrees otherwise in writing in its
sole and absolute discretion and any such assignment or sublease shall, at
Landlord's option, be void in the event that Tenant and each such guarantor, if
any, does not expressly acknowledge and affirm its continuing liability in form
and substance reasonably satisfactory to Landlord. The continuing liability of
the assigning Tenant shall be primary, and Landlord shall be entitled to
exercise its rights and remedies against any such assignor with respect to any
Tenant Default without exhausting its rights and remedies against any successor
of such assignor with respect to any Tenant Default without exhausting its
rights and remedies against any successor of such assignor. In the event that it
is ever held, notwithstanding the contrary intention of the parties hereto, that
any such assignor's continuing liability is that of a guarantor (rather than
primary), Tenant hereby waives any and all suretyship rights and defenses to
which it would otherwise be entitled in connection with such continuing
liability. Notwithstanding the foregoing, in the event that, following any
assignment (other than an assignment described in Article 16(B), above),
Landlord and such assignee modify this Lease in such a way as to increase
Tenant's total obligations hereunder, neither the assigning Tenant nor any
guarantor whose guaranty pre-dated such assignment shall be liable for the
incremental portion of Tenant's obligations corresponding to such increase. The
acceptance of any assignment by an assignee shall automatically constitute the
assumption by such assignee of all obligations of Tenant with respect to the
assigned premises; provided, however, that any assignment of this Lease shall,
at Landlord's option, be void in the event that the assignee does not expressly
acknowledge and affirm the effectiveness of the foregoing assumption in form and
substance reasonably satisfactory to Landlord. Any assignment or subletting by
Tenant to which Landlord's consent is required but not obtained shall, at
Landlord's option, be void.

                  F.       Other Provisions Applicable to Transfers. No
assignment or subletting shall be deemed to modify any provision of this Lease,
with respect to permitted or restricted uses of the Premises or otherwise,
unless Landlord then agrees otherwise in writing in its absolute discretion.
Tenant shall promptly furnish Landlord with a copy of each executed assignment
or sublease, and with copies of any supplements or modifications thereto which
may be executed from time to time.

                  G.       Assignment of Sublease Revenues. Tenant hereby
assigns to Landlord all of Tenant's right, title and interest in and to all
revenues from each sublease of all or any portion of the Premises; provided,
however, that Landlord hereby grants Tenant a license, which shall remain in
effect so long as no Tenant default remains uncured beyond applicable notice and
cure provisions(s), to collect all such revenues (subject to Tenant's obligation
to deliver certain of such revenues to Landlord under this Article). Upon the
occurrence of any Tenant default beyond applicable notice and cure
provisions(s), Landlord may revoke such license by written notice to Tenant and
may, by written notice to any subtenant of Tenant, demand that such subtenant
pay all such revenues directly to Landlord. In such event, Tenant hereby
irrevocably authorizes and directs any such subtenant to pay such revenues to
Landlord, and further agrees (a) that any such subtenant shall be obligated and
entitled to pay such revenues to Landlord notwithstanding any contrary
contentions or instructions later received from Tenant and (b) that no such
subtenant shall have any liability to Tenant for any such revenues paid to
Landlord in accordance with the foregoing. Landlord shall not be entitled to use
or enjoy any such revenues except for the purpose of applying such revenues
against unfulfilled obligations of Tenant hereunder with respect to which the
applicable cure periods have expired, or to reimburse Landlord for costs
reasonably incurred as a result of any Tenant default, or to compensate Landlord
for other losses suffered by Landlord as a result of any Tenant default. Any
such revenues remaining in Landlord's possession following the cure of all
Tenant defaults and the reimbursement of all such costs and losses shall be
delivered to Tenant upon demand. No such notice to any subtenant or receipt of
revenues from any subtenant shall be deemed to constitute either (i) Landlord's
consent to

                                     - 27 -
<PAGE>

such sublease or (ii) the assumption by Landlord of any obligation of Tenant
under such sublease, nor shall any such notice or receipt create privity of
contract between Landlord and the applicable subtenant or be construed as a
nondisturbance or similar agreement between Landlord and such subtenant.

                  H.       Transfers by Subtenants. The provisions of this
Article shall also apply to assignments and subleases by subtenants,
sub-subtenants and so on.

                  I.       Assignment of Options. Except as to transfers under
Article 16(B), without limiting the generality of any provision of this Lease
which states that any option or other right of Tenant is personal to the
original Tenant hereunder or may only be assigned under certain conditions, no
option or similar right of Tenant hereunder, including without limitation any
option to extend or renew, option to expand, first offer or first refusal right,
or first right to lease, may be assigned, and any attempt to assign such right
shall be null and void.

                  J.       Encumbrance. Tenant shall not assign its interests
hereunder as security for any obligation without Landlord's prior written
consent, which may be withheld in Landlord's absolute discretion, and any such
assignment without such consent shall, at Landlord's option, be void.

                  K.       Transfer Fee. Whether or not Landlord consents to any
such transfer, Tenant shall pay to Landlord Landlord's then standard processing
fee and reasonable attorneys' fees incurred in connection with the proposed
transfer up to the aggregate sum of $1,500.00.

                                   ARTICLE 17.

               SUBORDINATION, ATTORNMENT AND MORTGAGEE PROTECTION

                  This Lease is subject and subordinate to all Mortgages now or
hereafter placed upon the Property, and all other encumbrances and matters of
public record applicable to the Property, including without limitation, any
reciprocal easement or operating agreements, ground or underlying leases, and
Tenant shall not act or permit the Premises to be operated in violation thereof
and Landlord shall have the right to cause this Lease to be and become and
remain subject and subordinate to any and all ground or underlying leases or
Mortgages which may hereafter be executed covering the Premises, the Building or
the Property or any renewals, modifications, consolidations, replacements or
extensions thereof, for the full amount of all advances made or to be made
thereunder and without regard to the time or character of such advances,
together with interest thereon and subject to all the terms and provisions
thereof; provided, however, in all such cases that Landlord obtains from any
Lender or other party in question a written undertaking in favor of Tenant to
the effect that such Lender or other party will not disturb Tenant's right of
possession under this Lease if Tenant is not then or thereafter in breach of any
covenant or provision of this Lease beyond applicable notice and cure
provision(s). Tenant agrees, within ten business (10) days after Landlord's
written request therefor, to execute, acknowledge and deliver upon request any
and all reasonable documents or instruments requested by Landlord or necessary
or proper to assure the subordination of this Lease to any such Mortgages, deeds
of trust, or leasehold estates. If any foreclosure or power of sale proceedings
are initiated by any Lender or a deed in lieu is granted (or if any ground lease
is terminated), Tenant agrees, upon written request of any such Lender or any
purchaser at such foreclosure sale, to attorn and pay Rent to such party and to
execute and deliver any instruments necessary or appropriate to evidence or
effectuate such attornment, within ten (10) business days of Landlord's request
therefor. In the event of attornment, no Lender shall be: (i) liable for any act
or omission of Landlord, or subject to any offsets or defenses which Tenant
might have against Landlord except for the payment of any outstanding Tenant
Work Allowance (prior to such Lender becoming

                                     - 28 -
<PAGE>

Landlord under such attornment), (ii) liable for any security deposit or bound
by any prepaid Rent not actually received by such Lender, or (iii) bound by any
future modification of this Lease not consented to by such Lender. Any Lender
may elect to make this Lease prior to the lien of its Mortgage, and if the
Lender under any prior Mortgage shall require, this Lease shall be prior to any
subordinate Mortgage; such elections shall be effective upon written notice to
Tenant. Tenant agrees to give any Lender by certified mail, return receipt
requested, a copy of any notice of default served by Tenant upon Landlord,
provided that prior to such notice Tenant has been notified in writing (by way
of service on Tenant of a copy of an assignment of leases, or otherwise) of the
name and address of such Lender. Tenant further agrees that if Landlord shall
have failed to cure such default within the time permitted Landlord for cure
under this Lease unless the curing is urgent to Tenant's business operations,
any such Lender whose address has been so provided to Tenant shall have an
additional period of thirty (30) days in which to cure (or such additional time
as may be required due to causes beyond such Lender's control, including time to
obtain possession of the Building by power of sale or judicial action or deed in
lieu of foreclosure if required by law to effect such cure). The provisions of
this Article shall be self-operative; however, Tenant shall execute such
reasonable documentation as Landlord or any Lender may request from time to time
in order to confirm the matters set forth in this Article in recordable form. To
the extent not expressly prohibited by Law, Tenant waives the provisions of any
Law now or hereafter adopted which may give or purport to give Tenant any right
or election to terminate or otherwise adversely affect this Lease or Tenant's
obligations hereunder if such foreclosure or power of sale proceedings are
initiated, prosecuted or completed.

                                   ARTICLE 18.

                              ESTOPPEL CERTIFICATE

                  Tenant shall from time to time, upon written request by
Landlord or any Lender, execute, acknowledge and deliver to Landlord or such
Lender, within ten (10) business days after receipt of such request, a statement
in writing certifying, without limitation: (i) that this Lease is unmodified and
in full force and effect (or if there have been modifications, identifying such
modifications and certifying that the Lease, as modified, is in full force and
effect); (ii) the dates to which Rent and any other charges have been paid;
(iii) that Landlord is not in default under any provision of this Lease (or if
Landlord is in default, specifying each such default) and that, if true, no
events or conditions exist which, with the passage of time or notice or both,
would constitute a default on the part of Landlord hereunder; (iv) the address
to which notices to Tenant shall be sent; (v) the amount of Tenant's security
deposit and (vi) such other factual statements as may be reasonably requested by
Landlord; it being understood that any such statement so delivered may be relied
upon in connection with any lease, mortgage or transfer.

                  Tenant's failure to deliver such statement within such time
shall be conclusive upon Tenant that: (i) this Lease is in full force and effect
and has not been modified except as Landlord may represent; (ii) not more than
one (1) month's Rent has been paid in advance; (iii) there are no defaults by
Landlord; (iv) notices to Tenant shall be sent to Tenant's Address as set forth
in Article 1 of this Lease; and (v) that all other statements contained in such
estoppel are true and correct. Notwithstanding the presumptions of this Article,
Tenant shall not be relieved of its obligation to deliver said statement.

                                     - 29 -
<PAGE>

                                   ARTICLE 19.

                                    DEFAULTS

                  A.       Tenant Defaults: The occurrence of any of the
following shall constitute a "default" by Tenant hereunder:

                           (a)      Tenant fails to pay when due any installment
         or other payment of Rent or any other amount owing to Landlord within
         five (5) days after written notice from Landlord; or

                           (b)      Tenant fails to keep in effect any insurance
         required to be maintained hereunder, and such failure continues for
         thirty (30) days after notice thereof given by or on behalf of
         Landlord; or

                           (c)      Intentionally Omitted.

                           (d)      Tenant becomes insolvent, makes an
         assignment for the benefit of creditors, files a voluntary petition in
         bankruptcy or an involuntary petition in bankruptcy is filed against
         Tenant which petition is not dismissed within ninety (90) days of its
         filing; or

                           (e)      Tenant fails to cause to be released or
         bonded over any mechanic's liens filed against the Premises or the
         Property due to a contract between Tenant and the holder of such lien
         within twenty (20) days after the date the same shall have been filed
         or recorded; or

                           (f)      Tenant fails to observe or perform according
         to the provisions of Article 17 or 18 within the time periods specified
         in such Articles and such failure continues for five (5) days after
         notice given by or on behalf of Landlord of such failure to observe the
         time periods specified in such Articles; or

                           (g)      A receiver is appointed for Tenant's
         business or assets and the appointment of such receiver is not vacated
         within ninety (90) days after such appointment; or

                           (h)      Tenant fails to perform or observe any of
         the other covenants, conditions or agreements contained herein on
         Tenant's part to be kept or performed or breaches a representation made
         hereunder, and such failure shall continue for thirty (30) days after
         notice thereof is given by or on behalf of Landlord, or if such default
         is curable but cure cannot reasonably be effected within such thirty
         (30) day period, such default shall not be a default hereunder so long
         as Tenant promptly commences cure within thirty (30) days and
         thereafter diligently prosecutes such cure to completion; or

                           (i)      Except for transfers under Article 16, if
         the interest of Tenant shall be offered for sale or sold under
         execution or other legal process.

                  All notices required to be given under this paragraph shall be
in lieu of, and not in addition to any notice requirements imposed by law,
statute, ordinance, governmental regulation or requirement of the United States,
the State in which the Building is located or any local government authority or
agency or any political subdivision thereof, now or hereafter in effect.

                                     - 30 -
<PAGE>

                  If any alleged default on the part of the Landlord hereunder
occurs, Tenant shall give written notice to Landlord in the manner herein set
forth and shall afford Landlord a reasonable opportunity to cure any such
default. In addition, Tenant shall send notice of such default by certified or
registered mail, postage prepaid, to the holder of any Mortgage whose address
Tenant has been provided in writing, and shall afford such Mortgage holder a
reasonable opportunity (subject to the provisions of Article 17) to cure any
alleged default on Landlord's behalf. In no event will Landlord be responsible
for consequential damages incurred by Tenant, including but not limited to, lost
profits or interruption of business as a result of any alleged default by
Landlord hereunder.

                                   ARTICLE 20.

                                    REMEDIES

                  A.       Landlord Remedies. The remedies provided Landlord
under this Lease are cumulative. Upon the occurrence of any default by Tenant,
and in addition to any and all other rights provided a landlord under law or
equity for breach of a lease or tenancy by a tenant, Landlord shall have the
right to pursue one or more of the following remedies:

                           (a)      Landlord may serve notice on Tenant that the
         Term and the estate hereby vested in Tenant and any and all other
         rights of Tenant hereunder shall cease on the date specified in such
         notice and on the specified date this Lease shall cease and expire as
         fully and with the effect as if the Term had expired for passage of
         time.

                           (b)      Without terminating this Lease in case of a
         default or if this Lease shall be terminated for default as provided
         herein, Landlord may re-enter the Premises, remove Tenant, or cause
         Tenant to be removed from the Premises in such manner as Landlord may
         deem advisable, with or without legal process. In the event of re-entry
         without terminating this Lease, Tenant shall continue to be liable for
         all Rents and other charges accruing or coming due under this Lease
         which Rent shall automatically accelerate and become immediately due
         and payable.

                           (c)      If Landlord, without terminating this Lease,
         shall re-enter the Premises or if this Lease shall be terminated as
         provided in paragraph (a) above:

                                    (i)      All Rent due from Tenant to
                  Landlord shall thereupon become due and shall be paid up to
                  the time of re-entry, dispossession or expiration, together
                  with reasonable costs and expenses (including, without
                  limitation, attorneys' fees) of Landlord and without benefit
                  of valuation and appraisement laws which Tenant hereby waives;

                                    (ii)     Landlord shall use commercially
                  reasonable efforts to relet the Premises or any part thereof
                  for a term or terms which may at Landlord's option be less
                  than or exceed the period which would otherwise have
                  constituted the balance of the Term and may grant such
                  concessions in reletting as Landlord, in the exercise of its
                  reasonable business judgment, deems desirable. Tenant agrees
                  that Landlord shall have satisfied its obligation to attempt
                  to relet the Premises if Landlord offers the Premises for
                  reletting in the normal course of its business, without
                  preference over any other premises in the Building. In
                  connection with such reletting, Tenant shall be liable for all
                  costs of the reletting including, without limitation, rent
                  concessions, leasing commissions, legal fees and alteration
                  and remodeling costs; and

                                     - 31 -
<PAGE>

                                    (iii)    If Landlord shall have terminated
                  this Lease, Tenant shall also be liable to Landlord for the
                  positive difference, if any, between the aggregate Rents
                  reserved under the terms of this Lease for the balance of the
                  Term together with all other sums payable hereunder as Rent
                  for the balance of the Term, less the fair rental value of the
                  Premises for that period determined as of the date of such
                  termination. For purposes of this paragraph, Tenant shall be
                  deemed to include any guarantor or surety of the Lease.

                           (d)      Landlord may continue this Lease in effect
                  after Tenant's breach and abandonment and recover Rent as it
                  becomes due.

                           (e)      Whether or not Landlord terminates this
                  Lease, Landlord shall have the right, as Landlord chooses in
                  its absolute discretion, (i) to terminate any or all
                  subleases, licenses, concessions and other agreements entered
                  into by Tenant in connection with its occupancy of the
                  Premises and/or (ii) to maintain any or all such agreements in
                  effect and succeed to Tenant's interests in connection
                  therewith (in which event Tenant shall cease to have any
                  interest in any such agreement). This subsection (e) shall not
                  apply to any subtenant or licensee with whom Landlord has
                  previously entered into a so-called recognition agreement.

                           (f)      Attorneys' Fees.

                                    (i)      In any action to enforce the terms
                  of this Lease, including any suit by Landlord for the recovery
                  of Rent or possession of the Premises, the losing party shall
                  reimburse the successful party for its reasonable attorneys'
                  fees incurred in such suit and such attorneys' fees shall be
                  deemed to have accrued prior to the commencement of such
                  action and shall be paid whether or not such action is
                  prosecuted to judgment.

                                    (ii)     Should Landlord, without fault on
                  Landlord's part, be made a party to any litigation instituted
                  by Tenant or by any third party against Tenant, or by or
                  against any person holding under or using the Premises by
                  license of Tenant, or for the foreclosure of any lien for
                  labor or material furnished to or for Tenant or any such other
                  person or otherwise arising out of or resulting from any act
                  or transaction of Tenant or of any such other person, Tenant
                  covenants to save and hold Landlord harmless from and against
                  any judgment rendered against Landlord or the Premises or any
                  part thereof and from and against all costs and expenses,
                  including reasonable attorneys' fees, incurred by Landlord in
                  connection with such litigation.

                           (g)      In addition to the above and except as
         otherwise provided herein, Landlord shall have any and all other rights
         provided a landlord at law or in equity, including, but not limited to,
         those remedies provided for by laws, statutes, ordinances, governmental
         regulations or requirements of the United States, the State in which
         the Building is located or any local government authority or agency or
         any political subdivision thereof, now or hereafter in effect, for
         breach of a lease or tenancy by a tenant.

                           (h)      TENANT HEREBY WAIVES ALL RIGHT TO TRIAL BY
         JURY IN ANY CLAIM, ACTION PROCEEDING OR COUNTERCLAIM BY EITHER LANDLORD
         OR TENANT AGAINST THE OTHER OR ANY MATTER ARISING OUT OF OR IN ANY WAY
         CONNECTED WITH THIS LEASE, THE RELATIONSHIP OF

                                     - 32 -
<PAGE>

         LANDLORD AND TENANT, AND/OR TENANT'S USE OR OCCUPANCY OR THE PREMISES.

                  B.       Tenant Remedies. Upon the occurrence of any default
by Landlord, Tenant shall, except as otherwise expressly provided herein, have
any and all other rights provided a tenant at law or in equity, including, but
not limited to, those remedies provided for by laws, statutes, ordinances,
governmental regulations or requirements of the United States, the State in
which the Building is located or any local government authority or agency or any
political subdivision thereof, now or hereafter in effect, for breach of a lease
by a landlord; provided, however, that Tenant shall in no event have the right
to terminate this Lease except as expressly provided herein or as provided by
law.

                                   ARTICLE 21.

                                 QUIET ENJOYMENT

                  Landlord covenants and agrees with Tenant that so long as
Tenant pays Rent and observes and performs all the terms, covenants, and
conditions of this Lease on Tenant's part to be observed and performed, Tenant
may peaceably and quietly enjoy the Premises subject, nevertheless, to the terms
and conditions of this Lease, and Tenant's possession will not be disturbed by
anyone claiming by, through, or under Landlord, including, without limitation,
Palm, Inc. ("Palm"), whose lease had previously included the Premises. Landlord
specifically represents and warrants to Tenant that said lease with Palm has
been amended, on or prior to the date hereof, so that Landlord has the full
right to enter into this Lease with Tenant upon the terms and conditions
contained herein.

                                   ARTICLE 22.

                             ACCORD AND SATISFACTION

                  No payment by Tenant or receipt by Landlord of an amount less
than full payment of Rent then due and payable shall be deemed to be other than
on account of Rent then due and payable, nor shall any endorsement or statement
on any check or any letter accompanying any check or payment as Rent 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 Rent or
pursue any other remedy provided for in this Lease or available at law or in
equity.

                                   ARTICLE 23.

                                SECURITY DEPOSIT

                  To secure the full and faithful performance by Tenant of all
of the covenants, conditions and agreements set forth in this Lease to be
performed by it, including, without limitation, the foregoing such covenants,
conditions and agreements in this Lease which become applicable upon its
termination by re-entry or otherwise, Tenant has deposited with Landlord the sum
shown in Article 1 as a "Security Deposit" on the understanding:

                           (a)      that the Security Deposit or any portion
         thereof may be applied to the curing of any default beyond applicable
         notice and cure period(s) that may exist, including but not limited to
         a breach for failure to pay Rent, without prejudice to any other remedy
         or remedies which Landlord may have on account thereof, and upon such
         application Tenant

                                     - 33 -
<PAGE>

         shall restore to Landlord on demand the amount so applied which shall
         be added to the Security Deposit so the same will be restored to its
         original amount;

                           (b)      that should the Premises be conveyed by
         Landlord, the Security Deposit or any balance thereof shall be turned
         over to the Landlord's grantee, and Tenant hereby releases Landlord
         from any and all liability with respect to the Security Deposit, if so
         transferred, and its application or return, and Tenant agrees to look
         solely to such grantee for such application or return;

                           (c)      that Landlord may not commingle the Security
         Deposit with other funds;

                           (d)      that the Security Deposit shall not be
         considered an advance payment of Rent or a measure of damages for any
         default by Tenant, nor shall it be a bar or defense to any actions by
         Landlord against Tenant; and

                           (e)      Intentionally Omitted.

                           (f)      that if Tenant shall faithfully perform all
         of the covenants and agreements contained in this Lease on the part of
         the Tenant to be performed, and provided there exists no default by
         Tenant hereunder, the Security Deposit or any then remaining balance
         thereof, shall be returned to Tenant, without interest, within thirty
         (30) days after the expiration of the Term, provided that subsequent to
         the expiration of this Lease, Landlord may retain from the Security
         Deposit (i) an amount reasonably estimated by Landlord to cover
         potential Operating Expense reconciliation payments due with respect to
         the calendar year in which this Lease terminates or expires (such
         amount so retained shall not, in any event, exceed ten percent (10%) of
         estimated Operating Expense payments due from Tenant for such calendar
         year through the date of expiration or earlier termination of this
         Lease and any amounts so retained and not applied to such
         reconciliation shall be returned to Tenant within thirty (30) days
         after Landlord's delivery of the Statement for such calendar year), and
         (ii) any and all amounts reasonably estimated by Landlord to cover the
         anticipated costs to be incurred by Landlord to remove any signage
         provided to Tenant under this Lease and to repair any damage caused by
         such removal (in which case any excess amount so retained by Landlord
         shall be returned to Tenant within thirty (30) days after such removal
         and repair). Tenant hereby waives any and all provisions of law, now or
         hereafter in effect in the State in which the Building is located or
         any local government authority or agency or any political subdivision
         thereof, that limit the types of defaults for which a landlord may
         claim sums from a security deposit, it being agreed that Landlord, in
         addition, may claim those sums specified in this Article 24 above
         and/or those sums reasonably necessary to compensate Landlord for any
         other loss or damage, caused by the acts or omissions of Tenant or any
         officer, employee, agent, contractor or invitee of Tenant. Tenant
         further covenants that it will not assign or encumber the money
         deposited herein as a Security Deposit and that neither Landlord nor
         its successors or assigns shall be bound by any such assignment,
         encumbrance, attempted assignment or attempted encumbrance.

                           (g)      at Tenant's election, in lieu of a cash
security deposit, Tenant, simultaneously with the execution of this Lease, shall
deliver to Landlord (as beneficiary), and a copy to Landlord's attorney, a
standby letter of credit ("Letter of Credit") in form and content satisfactory
to Landlord. The Letter of Credit shall be, among other things:

                           (i)      subject to International Standby Practices
                           1998, International

                                     - 34 -
<PAGE>

                           Chamber of Commerce Publication No. 590;

                           (ii)     irrevocable and unconditional;

                           (iii)    in the amount of the required Security
                           Deposit;

                           (iv)     conditioned for payment solely upon
                           presentation of the Letter of Credit and a sight
                           draft, and

                           (v)      transferable one or more times by Landlord
                           without the consent of Tenant.

         The Letter of Credit shall be issued by a member of the New York
Clearing House Association or a commercial bank or trust company reasonably
satisfactory to Landlord. The Letter of Credit shall expire not earlier than 12
months after the date of delivery thereof to Landlord and shall provide that
same shall be automatically renewed for successive 12 month periods through a
date which is not earlier than 60 days after the expiration date of the Letter
of Credit, or any renewal or extension thereof, unless written notice of
non-renewal has been given by the issuing bank to Landlord and Landlord's
attorney by registered or certified mail, return receipt requested, not less
than 60 days prior to the expiration of the current period. If the issuing bank
does not renew the Letter of Credit, and if Tenant does not deliver a substitute
Letter of Credit at least 30 days prior to the expiration of the current period,
then in addition to its rights granted under Article 23 of the Lease, Landlord
shall have the right to draw on the existing Letter of Credit. With respect to
draws on the Letter of Credit:

                           (i)      Landlord may use, apply, or retain the
                                    proceeds of the Letter of Credit to the same
                                    extent that Landlord may use, apply, or
                                    retain the cash security deposit, as set
                                    forth above in this Article 23;

                           (ii)     Landlord may draw on the Letter of Credit,
                                    in whole or in part, from time to time, in
                                    the event of default by Tenant beyond
                                    applicable notice and cure period(s)
                                    provided, however, that no such language or
                                    other condition shall be contained in the
                                    Letter of Credit; and

                           (iii)    If Landlord partially draws down the Letter
                                    of Credit, Tenant shall within ten (10) days
                                    after Landlord gives Tenant notice thereof,
                                    restore all amounts drawn by Landlord, or
                                    substitute cash security instead.

         Tenant hereby agrees to cooperate with Landlord to promptly execute and
deliver to Landlord any and all modifications, amendments and replacements of
the Letter of Credit, as Landlord may reasonably request to carry out the terms
and conditions of this Article 23.

                                   ARTICLE 24.

                              BROKERAGE COMMISSION

                  Landlord and Tenant represent and warrant to each other that
neither has dealt with any broker, finder or agent except for the Brokers
identified in Article 1. Tenant and Landlord represent and warrant to each other
that (except with respect to the Brokers identified in Article 1, with whom
Landlord has entered into a separate brokerage agreement) no broker, agent,
commission salesperson, or other person has represented it in the negotiations
for and procurement of this Lease and of the Premises and that no commissions,
fees, or compensation of any kind are due and payable in connection herewith to
any broker, agent commission salesperson, or other person. Tenant and

                                     - 35 -
<PAGE>

Landlord agree to indemnify and hold harmless each other, its agents, members,
partners, representatives, officers, affiliates, shareholders, employees,
successors and assigns from and against any and all loss, liabilities, claims,
suits, or judgments (including, without limitation, reasonable attorneys' fees
and court costs incurred in connection with any such claims, suits, or
judgments, or in connection with the enforcement of this indemnity) for any
fees, commissions, or compensation of any kind which arise out of or are in any
way connected with any claimed agency relationship not referenced in Article 1.

                                   ARTICLE 25.

                                  FORCE MAJEURE

                  Anything to the contrary in this Lease notwithstanding,
Landlord and Tenant shall be excused for the period of any delay in the
performance of any obligation hereunder when prevented from so doing by a cause
or causes beyond its control, including all labor disputes, civil commotion,
war, war-like operations, invasion, rebellion, hostilities, military or usurped
power, sabotage, governmental regulations or controls, fire or other casualty,
inability to obtain any scarce material or services, or through acts of God;
provided:

                           (a)      nothing contained in this Section or
         elsewhere in this Lease shall be deemed to excuse or permit any delay
         in the payment of Rent, or any delay in the cure of any default which
         may be cured by the payment of money; and

                           (b)      no reliance by either party upon this
         Section shall limit or restrict in any way the other party's right of
         self-help as provided in this Lease.

                                   ARTICLE 26.

                                     PARKING

                           (a)      Landlord hereby grants to Tenant the right,
         in common with others authorized by Landlord, to use the parking
         facilities owned by Landlord and to use no more than the number of
         parking spaces made available to Tenant as set forth in Article 1(R)
         unless another tenant has a higher ratio of parking spaces to rentable
         square feet, in which event Tenant's number of spaces shall be
         increased accordingly, at Tenant's option, notwithstanding the number
         of Tenant's employees, customers or invitees. However, until the
         Building is fully leased, Tenant shall have the right to rent
         additional spaces on a pro rata basis with other Tenants. Landlord, at
         its sole election, may designate the types, sizes, configuration, and
         locations of parking spaces within the parking facilities which Tenant
         shall be allowed to use. Landlord shall have the right, at Landlord's
         sole election, to change said types, sizes, configuration, and
         locations (but never the number of Tenant's spaces) from time to time;
         provided, however, such designation shall be uniformly applied and
         shall not unfairly favor any tenant in the Building. Tenant's right to
         use the parking spaces is appurtenant to the Premises and Tenant may
         not assign, sublet or otherwise transfer any right to use any parking
         spaces except in connection with an assignment of this Lease or
         sublease of all or a portion of the Premises approved by Landlord or as
         permitted by this Lease without requiring Landlord's approval.

                           (b)      Commencing on the Rent Commencement Date,
         Tenant shall pay Landlord the Parking Fee, if any, shown in Article 1,
         as Additional Rent, payable monthly in advance with the Monthly Rent.
         In addition to the right reserved hereunder by Landlord to

                                     - 36 -
<PAGE>

         designate the parking rate from time to time, Landlord shall have the
         right to change the parking rate at any time, but never to exceed fair
         market rental for similar spaces similarly situated in Cambridge, MA,
         to include therein any amounts levied, assessed, imposed or required to
         be paid to any governmental authority on account of the parking of
         motor vehicles, including all sums required to be paid pursuant to
         transportation controls imposed by the Environmental Protection Agency
         under the Clean Air Act of 1970, as amended, or otherwise required to
         be paid by any governmental authority with respect to the parking, use,
         or transportation of motor vehicles, or the reduction or control of
         motor vehicle traffic, or motor vehicle pollution. Tenant shall be
         responsible for the full amount of any special parking taxes imposed by
         any governmental authority in connection with the use of the parking
         facility by Tenant.

                           (c)      If requested by Landlord, Tenant shall
         notify Landlord of the license plate number, year, make and model of
         the automobiles entitled to use the parking facilities and if requested
         by Landlord, such automobiles shall be identified by automobile window
         stickers provided by Landlord, and only such designated automobiles
         shall be permitted to use the parking facilities. If Landlord
         institutes such an identification procedure, Landlord may, in its sole
         discretion, provide additional parking spaces for use by customers and
         invitees of Tenant on a daily basis at prevailing parking rates, if
         any. At Landlord's sole election, Landlord may make validation stickers
         available to Tenant for any such additional parking spaces, provided,
         however, if Landlord makes validation stickers available to any other
         tenant in the Building, Landlord shall make such validation stickers
         available to Tenant. In the event Tenant exceeds the number of allotted
         parking spaces set forth in Article 1(S) or if Landlord has instituted
         a window sticker or other parking procedure and Tenant's employees,
         customers or invitees do not comply with any such procedure, then in
         any of such events, Landlord shall be entitled to, without any
         liability to Tenant, its employees, customers or invitees, any vehicles
         not complying with Landlord's procedures or parking in excess of such
         allotted number of spaces. Tenant acknowledges and agrees that Landlord
         may, without incurring any liability to Tenant and without any
         abatement of Rent under this Lease, from time to time, close-off or
         restrict access to the parking facility for purposes of permitting or
         facilitating necessary construction, alteration or improvement.
         Landlord may delegate its responsibilities hereunder to a parking
         operator or a lessee of the parking facility in which case such parking
         operator or lessee shall have all the rights of control attributed
         hereby to the Landlord.

                           (d)      The parking facilities provided for herein
         are provided solely for the accommodation of Tenant, and Landlord
         assumes no responsibility or liability of any kind whatsoever from
         whatever cause with respect to the automobile parking areas, including
         adjoining streets, sidewalks, driveways, property and passageways, or
         the use thereof by Tenant or tenant's employees, customers, agents,
         contractors or invitees. Tenant may not assign, transfer, sublease or
         otherwise alienate the use of the parking facilities without Landlord's
         prior written consent.

                                   ARTICLE 27.

                               HAZARDOUS MATERIALS

                  A.       Definition of Hazardous Materials. The term
"Hazardous Materials" for purposes hereof shall mean any chemical, substance,
materials or waste or component thereof which is now or hereafter listed,
defined or regulated as a hazardous or toxic chemical, substance, materials or
waste or component thereof by any federal, state or local governing or
regulatory body having jurisdiction, or which would trigger any employee or
community "right-to-know" requirements

                                     - 37 -
<PAGE>
adopted by any such body, or for which any such body has adopted any
requirements for the preparation or distribution of a materials safety data
sheet ("MSDS"). The term "Hazardous Material" includes, without limitation, any
material, waste or substance which is (i) included within the definitions of
"hazardous substances," "hazardous materials," or "toxic substances" in or
pursuant to any environmental Law, or subject to regulation under any
environmental Law, (ii) listed in the United States Department of Transportation
Optional Hazardous Material Table, 49 C.F.R. Section 172.101, as to date or
hereafter amended, or in the United States Environmental Protection Agency List
of Hazardous Substances and Reportable Quantities, 40 C.F.R. Part 302, as to
date or hereafter amended, (iii) an explosive, radioactive, asbestos,
polychlorinated biphenyl, oil or petroleum product, (iv) designated as a
"Hazardous Substance" pursuant to Section 311 of the Federal Water Pollution
Control Act (33 U.S.C. Section 1317), (v) defined as a "Hazardous Waste"
pursuant to Section 1004 of the Federal Resource Conservation and Recovery Act,
42 U.S.C. Section 6901 et seq. (42 U.S.C. Section 6903), (vi) defined as a
"Hazardous Substance" pursuant to Section 101 of the Comprehensive Environmental
Response, Compensation and Liability Act, 42 U.S.C. Section 9601 et seq. (42
U.S.C. Section 9601), or (vii) any substance deemed to be a "Hazardous Material"
by any federal, state or local Law, statute, regulation, ordinance, or any
judicial or administrative order or judgment thereunder, because it affects the
health, industrial hygiene or the environmental or ecological conditions on,
under or about the Premises or the Property.

                  B.       No Hazardous Materials. Tenant shall not transport,
use, store, maintain, generate, manufacture, handle, dispose, release or
discharge any Hazardous Materials. However, the foregoing provisions shall not
prohibit the transportation to and from, and use, storage, maintenance,
generation, manufacture and handling within the Premises of Hazardous Materials
customarily used in the business or activity expressly permitted to be
undertaken in the Premises under Article 6, provided: (a) such Hazardous
Materials shall be used and maintained only in such quantities as are reasonably
necessary for such permitted use of the Premises and the ordinary course of
Tenant's business therein, strictly in accordance with applicable Law, (b) such
Hazardous Materials shall not be disposed of in the Building or on the Property
and shall be released or discharged only in accordance with all applicable Laws,
and shall be transported to and from the Premises in compliance with all
applicable Laws, and as Landlord shall reasonably require, (c) if any applicable
Law or Landlord's trash removal contractor requires that any such Hazardous
Materials be disposed of separately from ordinary trash, Tenant shall make
arrangements, at Tenant's expense, for such disposal directly with a qualified
and licensed disposal company (subject to scheduling and approval by Landlord,
not to be reasonably withheld) at a lawful disposal site, and (d) any remaining
such Hazardous Materials shall be completely and lawfully removed from the
Building upon expiration or earlier termination of this Lease. Any clean up,
remediation and removal work required of Tenant by Law or the terms of this
Lease shall be subject to Landlord's prior written approval (except in
emergencies), and shall include, without limitation, any testing, investigation,
and the preparation and implementation of any remedial action plan required by
any governmental body having jurisdiction. If Landlord or any Lender or
governmental body arranges for any tests or studies showing that this Article
has been violated by Tenant, Tenant shall pay for the costs of such tests.

                  C.       Notices To Landlord. Tenant shall promptly notify
Landlord once Tenant obtains knowledge of: (i) any enforcement, cleanup or other
regulatory action taken or threatened by any governmental or regulatory
authority with respect to the presence of any Hazardous Materials on the
Premises or the migration thereof from or to other property, (ii) any demands or
claims made or threatened in writing by any party relating to any loss or injury
resulting from any Hazardous Materials on the Premises, (iii) any unlawful
release, discharge or unlawful disposal or transportation of any Hazardous
Materials on or from the Premises in violation of this Article, and (iv) any
matters where Tenant is required by Law to give a notice to any governmental or
regulatory authority respecting any Hazardous Materials on the Premises. At such
times as Landlord may reasonably request, Tenant shall provide Landlord with a
written list, certified to be true and complete, identifying

                                     - 38 -
<PAGE>

any Hazardous Materials then used, stored, or maintained upon the Premises, the
use and approximate quantity of each such materials, a copy of any MSDS issued
by the manufacturer therefor, and such other information as Landlord may
reasonably require or as may be required by Law.

                  D.       Indemnification. If any Hazardous Materials are
released, discharged or disposed of by Tenant or any other occupant of the
Premises, or their employees, agents, invitees or contractors, on or about the
Property in violation of the foregoing provisions, Tenant shall immediately and
in compliance with applicable Laws clean up, remediate and remove the Hazardous
Materials from the Property and any other affected property and clean or replace
any affected personal property not owned by Tenant (whether or not owned by
Landlord), at Tenant's expense (without limiting Landlord's other remedies
therefor). Tenant shall further be required to indemnify, hold harmless and
defend (by counsel reasonably acceptable to Landlord) Landlord, Landlord's
directors, officers, partners, employees, agents, successors and assigns from
and against any and all claims, demands, liabilities, losses, damages,
penalties, forfeitures, judgments or expenses (including reasonable attorneys'
fees) or death of or injury to any person or damage to any property whatsoever,
arising out of : (i) a violation of the provisions of this Article by Tenant,
Tenant's occupants, employees, contractors or agents; (ii) the presence in, on,
under or about the Premises or discharge in or from the Premises of any
Hazardous Materials placed in, under or about the Premises by Tenant or at
Tenant's direction, excluding any tenant improvement work done by Landlord;
(iii) Tenant's use, analysis, storage, transportation, disposal, release,
threatened release, discharge or generation of Hazardous Materials to, in, on,
under, about or from the Premises; or (iv) Tenant's failure to comply with any
Hazardous Materials Law applicable hereunder to Tenant. The provisions of this
Article shall survive the expiration or earlier termination of this Lease.

                  Landlord will indemnify, defend (by counsel reasonably
acceptable to Tenant), protect, and hold Tenant and each of Tenant's employees,
agents, successors and assigns, free and harmless from and against any and all
claims, demands, liabilities, damages, judgments, penalties, forfeitures, losses
or expenses (including reasonable attorney's fees) or death of or injury to any
person or damage to any property whatsoever, arising out of:

                                    (i)      the presence in, on, under or about
                  the Premises or the Building or discharge in or from the
                  Premises or the Building of any Hazardous Materials (A)
                  placed, in, on, under or about the Premises or the Building by
                  Landlord or at Landlord's direction or (B) existing as of the
                  date hereof; or

                                    (ii)     Landlord's use, analysis, storage,
                  transportation, disposal, release, threatened release,
                  discharge or generation of Hazardous Materials to, in, on,
                  under, about or from the Premises or the Building; or

                                    (iii)    Landlord's failure to comply with
                  any Hazardous Materials Law.

The obligations of each party pursuant to this Section include, without
limitation, and whether foreseeable or unforeseeable, all costs of any required
or necessary repair, cleanup or detoxification or decontamination of the
Premises or the Property, and the preparation and implementation of any closure,
remedial action or other required plans in connection therewith, and survives
the expiration or earlier termination of the term of the Lease.

                  E.       Subletting or Assignment. It shall not be
unreasonable for Landlord to withhold its consent to any proposed assignment or
subletting if (i) the proposed transferee's anticipated use of the Premises
involves the generation, storage, use, treatment, or disposal of

                                     - 39 -
<PAGE>

Hazardous Material and the proposed transferee has been required by any prior
landlord, lender, or governmental authority to take remedial action in
connection with Hazardous Material contaminating a property if the contamination
resulted from such transferee's actions or use of the property in question; or
(ii) the proposed transferee is subject to an enforcement order issued by any
governmental authority in connection with the use, disposal, or storage of a
Hazardous Material.

                                   ARTICLE 28.

                     ADDITIONAL RIGHTS RESERVED BY LANDLORD

                  In addition to any other rights provided for herein, Landlord
reserves the following rights, exercisable without liability to Tenant for
damage or injury to property, person or business and without effecting an
eviction, constructive or actual, or disturbance of Tenant's use or possession
or giving rise to any claim:

                           (a)      To name the Building provided, however, that
         Landlord (i) agrees not to name the Building using a name of a
         competitor of Tenant and (ii) shall not have this right for so long as
         Tenant continues to lease at least one (1) full floor of the Building;

                           (b)      To install and maintain all signs on the
         exterior and interior of the Building;

                           (c)      To designate all sources furnishing sign
         painting or lettering for use in the Building;

                           (d)      During the last ninety (90) days of the
         Term, if Tenant has vacated the Premises, to decorate, remodel, repair,
         alter or otherwise prepare the Premises for occupancy, without
         affecting Tenant's obligation to pay Rent for the Premises;

                           (e)      Subject to Tenant's reasonable security
         requirements, to have pass keys to the Premises and all doors therein,
         excluding Tenant's vaults and safes;

                           (f)      On reasonable prior notice to Tenant, to
         exhibit the Premises to any prospective purchaser, Lender, mortgagee,
         or assignee of any mortgage on the Building or the land on which the
         Building is located and to others having an interest therein at any
         time during the Term, and to prospective tenants during the last six
         (6) months of the Term;

                           (g)      Subject to Tenant's reasonable security
         requirements, to take any and all measures, including entering the
         Premises for the purpose of making inspections, repairs, alterations,
         additions and improvements to the Premises or to the Building
         (including for the purpose of checking, calibrating, adjusting and
         balancing controls and other parts of the Building Systems), as may be
         necessary or desirable for the operation, improvement, safety,
         protection or preservation of the Premises or the Building, or in order
         to comply with all Laws, orders and requirements of governmental or
         other authority, or as may otherwise be permitted or required by this
         Lease; provided, however, that during the progress of any work on the
         Premises or at the Building, Landlord will attempt not to inconvenience
         Tenant, but shall not be liable for inconvenience, annoyance,
         disturbance, loss of business, or other damage to Tenant by reason of
         performing any work or by bringing or storing materials, supplies,
         tools or equipment in the Building or Premises during the performance
         of any work, and the obligations of Tenant under this Lease shall not
         thereby be affected in any manner whatsoever;

                                     - 40 -
<PAGE>

                           (h)      To relocate various facilities (but never
         the Premises, except the acid neutralization or penthouse facility)
         within the Building and on the land of which the Building is a part
         (but not to within the Premises), if Landlord shall determine such
         relocation to be in the best interest of the development of the
         Building and such property, provided that such relocation shall not
         materially restrict access to the Premises; and

                           (i)      To install vending machines of all kinds in
         the Building and to receive all of the revenue derived therefrom,
         provided, however, that no vending machines shall be installed by
         Landlord in the Premises unless Tenant so requests.

                                   ARTICLE 29.

                                  DEFINED TERMS

                  A.       "Building" shall refer to the Building named in
Article 1 of which the Premises are a part (including all modifications,
additions and alterations made to the Building during the term of this Lease),
all plazas, common areas and any other areas located on the Property (as defined
below) and designated by Landlord for use by all tenants in the Building. A plan
showing the Building is attached hereto as Exhibit A and made a part hereof and
the Premises is defined in Article 2 and shown on said Exhibit A by
cross-hatched lines.

                  B.       "Common Areas" shall mean and include all areas,
facilities, equipment, directories and signs of the Building (exclusive of the
Premises and areas leased to other Tenants) made available and designated by
Landlord for the common and joint use and benefit of Landlord, Tenant and other
tenants and occupants of the Building including, but not limited to, lobbies,
public washrooms, hallways, sidewalks, parking areas, landscaped areas and
service entrances. Common Areas may further include such areas in adjoining
properties under reciprocal easement agreements, operating agreements or other
such agreements now or hereafter in effect and which are available to Landlord,
Tenant and Tenant's employees and invitees. Landlord reserves the right in its
reasonable discretion and from time to time, to construct, maintain, operate,
repair, close, limit, take out of service, alter, change, and modify all or any
part of the Common Areas.

                  C.       "Default Rate" shall mean eighteen percent (18%) per
annum, or the highest rate permitted by applicable law, whichever shall be less.
If the application of the Default Rate causes any provision of this Lease to be
usurious or unenforceable, the Default Rate shall automatically be reduced to
the highest rate allowed by law so as to prevent such result.

                  D.       "Hazardous Materials" shall have the meaning set
forth in Article 27.

                  E.       "Landlord" and "Tenant" shall be applicable to one or
more parties as the case may be, and the singular shall include the plural, and
the neuter shall include the masculine and feminine; and if there is more than
one (1), the obligations thereof shall be joint and several. For purposes of any
provisions indemnifying or limiting the liability of Landlord, the term
"Landlord" shall include Landlord's present and future partners, beneficiaries,
trustees, officers, directors, employees, shareholders, principals, agents,
affiliates, successors and assigns.

                  F.       "Law" or "Laws" shall mean all federal, state, county
and local governmental and municipal laws, statutes, ordinances, rules,
regulations, codes, decrees, orders and other such requirements, applicable
equitable remedies and applicable decisions by courts in cases where such
decisions are binding precedents in the state in which the Building is located,
and applicable decisions of federal courts applying the Laws of such state.

                                     - 41 -
<PAGE>

                  G.       "Lease" shall mean this lease executed between Tenant
and Landlord, including any extensions, amendments or modifications and any
Exhibits attached hereto.

                  H.       "Lease Year" shall mean each consecutive twelve (12)
month period thereof during the Term, with the first Lease Year commencing on
the Rent Commencement Date; however, (a) if the Rent Commencement Date falls on
a day other than the first day of a calendar month, the first Lease Year shall
end on the last day of the eleventh (11th) month after the Rent Commencement
Date and the second (2nd) and each succeeding Lease Year shall commence on the
first day of the next calendar month, and (b) the last Lease Year shall end on
the Expiration Date.

                  I.       "Lender" shall mean the holder of a Mortgage at the
time in question, and where such Mortgage is a ground lease, such term shall
refer to the ground lessee.

                  J.       "Mortgage" shall mean all mortgages, deeds of trust,
ground leases and other such encumbrances now or hereafter placed upon the
Property or any part thereof with the written consent of Landlord, and all
renewals, modifications, consolidations, replacements or extensions thereof, and
all indebtedness now or hereafter secured thereby and all interest thereon.

                  K.       "Operating Expenses" shall mean all reasonable
operating expenses of any kind or nature which are necessary, ordinary or
customarily incurred in connection with the operation, maintenance, replacement,
ownership or repair of the Property.

                  (a)      Operating Expenses shall include, but not be limited
                           to:

                  1.1      costs of supplies, including, but not limited to, the
cost of relamping all Building standard lighting as the same may be required
from time to time;

                  1.2      except for other tenant's special use(s), costs
incurred in connection with obtaining and providing energy for the Building,
including, but not limited to, costs of propane, butane, natural gas, steam,
electricity, solar energy and fuel oils, coal or any other energy sources,
including any taxes thereon but excluding any of the same except as to Common
Areas if the Premises are separately metered for the same;

                  1.3      except for other Tenant's special use(s), costs of
water and sanitary and storm drainage services but excluding any of the same
except as to Common Areas if the Premises are separately metered for the same;

                  1.4      except for other Tenant's special use(s), costs of
janitorial and security services;

                  1.5      costs of general maintenance and repairs, including
costs under HVAC, the intra-building network cable and other mechanical
maintenance contracts and maintenance, repairs and replacement of equipment and
tools used in connection with operating the Property and the parking facilities;

                  1.6      costs of maintenance and replacement of landscaping;

                  1.7      insurance premiums, including fire and all-risk
coverage, together with loss of rent endorsements, the part of any claim
required to be paid under the deductible portion of any insurance policies
carried by Landlord in connection with the Property (where Landlord is unable to
obtain insurance without such deductible from a major insurance carrier at
reasonable rates and such

                                     - 42 -
<PAGE>

deductible is comparable to deductibles of similar properties in Cambridge,
Massachusetts), public liability insurance and any other insurance carried by
Landlord on the Property, or any component parts thereof (all such insurance
shall be in such amounts as may be required by any holder of a Mortgage or as
Landlord may reasonably determine);

                  1.8      labor costs, including wages and other payments,
costs to Landlord of worker's compensation and disability insurance, payroll
taxes, employment taxes, general welfare benefits, pension payments, medical and
surgical benefits, fringe benefits, and all legal fees and other costs or
expenses incurred in resolving any labor dispute;

                  1.9      professional building management fees required for
management of the Property;

                  1.10     legal, accounting, inspection, and other consultation
fees (including, without limitation, fees charged by consultants retained by
Landlord for services that are designed to produce a reduction in Operating
Expenses or to reasonably improve the operation, maintenance or state of repair
of the Building) incurred in the ordinary course of operating the Property or in
connection with making the computations required hereunder or in any audit of
operations of the Property;

                  1.11     the costs of capital improvements or structural
repairs or replacements made in or to the Property in order to conform to
changes, subsequent to the date of this Lease, in any applicable Laws,
ordinances, rules, regulations or orders of any governmental or
quasi-governmental authority having jurisdiction over the Property (herein
"Required Capital Improvements") or the costs incurred by Landlord to install a
new or replacement capital item for the purpose of reducing Operating Expenses
(herein "Cost Savings Improvements") or the costs of repairing capital items
(herein "Capital Repairs"). The expenditures for Required Capital Improvements,
Cost Savings Improvements and Capital Repairs shall be amortized over the useful
life of such capital improvement or structural repair or replacement (as
reasonably determined by Landlord). All such costs shall bear interest on the
unamortized balance at the rate of ten percent (10%) per annum or such higher
rate as may have been paid by Landlord on funds borrowed for the purpose of
constructing or repairing these capital items provided, however, that with
respect to Cost Savings Improvements, in no event shall the annual amortization
thereof exceed the cost savings for any year.

                  (b)      Operating Expenses Exclusions

                  1.1      any increase in Landlord's insurance rates which may
result from the negligent failure of Landlord or its agents, employees or
contractors to comply with the provisions of this Lease;

                  1.2      depreciation;

                  1.3      interest on and amortization of debt;

                  1.4      the cost of leasehold improvements, including
redecorating work, for other tenants of the Building;

                  1.5      fees and expenses (including legal and brokerage
fees) for procuring new tenants for the Building;

                  1.6      costs incurred in financing or refinancing of the
Building;

                                     - 43 -
<PAGE>

                  1.7      the cost of any work or service performed for any
tenant in the Building (other than Tenant) to a materially greater extent or in
a materially more favorable manner than that furnished generally to tenants
(including Tenant) in the Building;

                  1.8      the cost of any repair or replacement which would be
required to be capitalized under generally accepted accounting principles except
as set forth in Section 29 K(a)1.11;

                  1.9      the cost of any item included in Operating Expenses
to the extent that Landlord is actually reimbursed for such cost by an insurance
company, a condemning authority, another tenant of any other party;

                  1.10     ground rent;

                  1.11     to the extent paid for from the management fee,
wages, salaries or other compensation paid to any employees at or below the
grade of Building manager, and in any event. salaries or other compensation paid
to employees above such grade;

                  1.12     wages, salaries or other compensation paid for clerks
or attendant in concessions or newsstands operated by Landlord;

                  1.13     the cost of correcting defects (latent or otherwise)
in the construction of the Building or in the Building equipment, except that
conditions (other than construction defects) resulting from ordinary wear and
tear shall not be considered defects for purposes hereof;

                  1.14     the cost of installing, operating and maintaining any
specialty service (e.g., observatory, broadcasting facility, luncheon club,
retail stores, newsstands or recreational club);

                  1.15     any costs representing an amount paid to a
corporation related to Landlord which is in excess of the amount which would
have been paid to an unrelated entity performing the same service;

                  1.16     payments for rented equipment outside the ordinary
course of business; and

                  1.17     any expenses for repairs or maintenance to the extent
reimbursed by warranties or service contracts.

                  L. "Property" shall mean the real property owned by Landlord
on which the Building is located and reference to the Property shall include the
Building.

                  M.       "Rent" shall have the meaning specified therefor in
Article 3.

                  N.       "Tax" or "Taxes" shall mean, subject to the
exclusions set forth in Article 4:

                  1.1      all real property taxes and assessments levied
against the Property by any governmental or quasi-governmental authority. The
foregoing shall include, without limitation, all federal, state, county, or
local governmental, special district, improvement district, municipal or other
political subdivision taxes, fees, levies, assessments, charges or other
impositions of every kind and nature, whether general, special, ordinary or
extraordinary, respecting the Property, including without limitation, real
estate taxes, general and special assessments, interest on any special
assessments paid in installments, transit taxes, water and sewer rents, taxes
based upon the receipt of rent, personal property taxes imposed upon the
fixtures, machinery, equipment, apparatus, appurtenances, furniture

                                     - 44 -
<PAGE>

and other personal property used in connection with the Property (but not of
other Tenants in the Building) which Landlord shall be obligated to pay during
any calendar year, any portion of which occurs during the Term (without regard
to any different fiscal year used by such government or municipal authority
except as provided below). Provided, however, any taxes which shall be levied on
the rentals of the Property shall be determined as if the Property were
Landlord's only property, and provided further that in no event shall the term
"taxes or assessment," as used herein, include any net federal or state income
taxes levied or assessed on Landlord, unless such taxes are a specific
substitute for real property taxes. Such term shall, however, include gross
taxes on rentals. Expenses incurred by Landlord for tax consultants and in
contesting the amount or validity of any such taxes or assessments shall be
included in such computations.

                  1.2      all "assessments", including so-called special
assessments, license tax, business license fee, business license tax, levy,
charge, penalty or tax imposed by any authority having the direct power to tax,
including any city, county, state or federal government, or any school,
agricultural, lighting, water, drainage, or other improvement or special
district thereof, against the Premises or the Property (but not premises of
other tenants) or any legal or equitable interest of Landlord therein. For the
purposes of this Lease, any special assessments shall be deemed payable in such
number of installments as is permitted by law, whether or not actually so paid.
If as of the Rent Commencement Date the Property has not been fully assessed as
a completed project, for the purpose of computing the Operating Expenses for any
adjustment required herein or under Article 4, the Tax shall be adjusted by
Landlord, as of the date on which the adjustment is to be made, to reflect full
completion of the Building including all standard Tenant finish work if the
method of taxation of real estate prevailing to the time of execution hereof
shall be, or has been altered, so as to cause the whole or any part of the taxes
now, hereafter or theretofore levied, assessed or imposed on real estate to be
levied, assessed or imposed on Landlord, wholly or partially, as a capital levy
or otherwise, or on or measured by the rents received therefrom, then such new
or altered taxes attributable to the Property shall be included within the term
real estate taxes, except that the same shall not include any enhancement of
said tax attributable to other income of Landlord. All of the preceding clauses
N (1.1 and 1.2) are collectively referred to as the "Tax" or "Taxes".

                  All other capitalized terms shall have the definition set
forth in the Lease.

                                   ARTICLE 30.

                            MISCELLANEOUS PROVISIONS

                  A.       RULES AND REGULATIONS.

                  Tenant shall comply with all reasonable of the rules and
regulations, consistently enforced and consistent with other laboratory
buildings in Cambridge, promulgated by Landlord from time to time for the
Property. A copy of the current rules and regulations is attached hereto as
Exhibit D. Landlord shall not be liable to Tenant for violation of any such
rules and regulations, or for the breach of any covenant or condition in any
lease by any other tenant in the Building.

                  B.       EXECUTION OF LEASE.

                  If Tenant is a corporation, partnership or limited liability
company, each individual executing this Lease on behalf of said entity
represents and warrants that he or she is duly authorized to execute and deliver
this Lease on behalf of said entity in accordance with: (i) if Tenant is a
corporation, a duly adopted resolution of the Board of Directors of said
corporation or in accordance with the by-laws of said corporation, (ii) if
Tenant is a partnership, the terms of the partnership

                                     - 45 -
<PAGE>

agreement, and (iii) if Tenant is a limited liability company, the terms of its
operating agreement, and that this Lease is binding upon said entity in
accordance with its terms. Concurrently with Tenant's execution of this Lease,
Tenant shall provide to Landlord a copy of: (i) if Tenant is a corporation, such
resolution of the Board of Directors authorizing the execution of this Lease on
behalf of such corporation, which copy of resolution shall be duly certified by
the secretary or an assistant secretary of the corporation to be a true copy of
a resolution duly adopted by the Board of Directors of said corporation and
shall be in a form reasonably acceptable to Landlord, (ii) if Tenant is a
partnership, a copy of the provisions of the partnership agreement granting the
requisite authority to each individual executing this Lease on behalf of said
partnership, and (iii) if Tenant is a limited liability company, a copy of the
provisions of its operating agreement granting the requisite authority to each
individual executing this Lease on behalf of said limited liability company.

                  C.       NOTICES.

                  All notices under this Lease shall be in writing and will be
deemed sufficiently given for all purposes if, to Tenant, by delivery to Tenant
at the Premises during the hours the Building is open for business or by
certified mail, return receipt requested or by overnight delivery service (with
one acknowledged receipt), to Tenant at the address set forth below, and if to
Landlord, by certified mail, return receipt requested or by overnight delivery
service (with one acknowledged receipt), at the addresses set forth below, or at
such other address from time to time established by Landlord.

                           Landlord: at address shown in Article 1, item F.

                           with a copy to: Building Manager at address shown in
                                           Article 1, item G.

                           Tenant: at address shown in Article 1, item B.

                           with copy to:     Joel R. Bloom, Esq.
                                             Mintz Levin Cohn Ferris Glovsky and
                                                Popeo, PC
                                             One Financial Center
                                             Boston, MA 02111

                  D.       TRANSFERS.

                  The term "Landlord" appearing herein shall mean only the owner
of the Building from time to time and, upon a sale or transfer of its interest
in the Building, the then landlord and transferring party shall have no further
obligations or liabilities for matters accruing after the date of transfer of
that interest. Tenant, upon such sale or transfer, agrees to attorn to the
transferee and shall look solely to the successor owner and transferee of the
Building, as the lessor under this Lease, for performance of Landlord's
obligations hereunder accruing after the date of transfer. Tenant shall, within
five (5) days after request, execute such further instruments or assurances as
such transferee may reasonably deem necessary to evidence or confirm such
attornment.

                  E.       INTENTIONALLY DELETED.

                  F.       TENANT FINANCIAL STATEMENTS.

                  Upon the written request of Landlord, Tenant shall submit
financial statements for its most recent financial reporting period and for the
prior Lease Year, when the same are generally available. Landlord shall make
such request no more than twice during any Lease Year. All such financial
statements shall be certified as true and correct by the responsible officer or
partner of Tenant

                                     - 46 -
<PAGE>

and if Tenant is then in default hereunder beyond applicable notice and cure
period(s), the financial statements shall be certified by an independent
certified public accountant.

                  G.       RELATIONSHIP OF THE PARTIES.

                  Nothing contained in this Lease shall be construed by the
parties hereto, or by any third party, as constituting the parties as principal
and agent, partners or joint venturers, nor shall anything herein render either
party (other than a guarantor) liable for the debts and obligations of any other
party, it being understood and agreed that the only relationship between
Landlord and Tenant is that of Landlord and Tenant.

                  H.       ENTIRE AGREEMENT; MERGER; SEVERABILITY.

                  This Lease and any Exhibits or Addenda hereto, embody the
entire agreement and understanding between the parties respecting the Lease and
the Premises and supersedes all prior negotiations, agreements and
understandings between the parties, all of which are merged herein. No provision
of this Lease may be modified, waived or discharged except by an instrument in
writing signed by the party against which enforcement of such modification,
waiver or discharge is sought. Any provision of this Lease which shall prove to
be invalid, void or illegal shall in no way affect, impact, impair or invalidate
any other provision hereof and such other provisions shall remain in full force
and effect.

                  I.       NO REPRESENTATION BY LANDLORD.

                  Neither Landlord nor any agent of Landlord has made any
representations, warranties, or promises with respect to the Premises or the
Property except as expressly set forth herein.

                  J.       LIMITATION OF LIABILITY.

                  Notwithstanding anything in this Lease to the contrary, any
remedy of Tenant for the collection of a judgment (or other judicial process)
requiring the payment of money by Landlord in the event of any default by
Landlord hereunder or any claim, cause of action or obligation, contractual,
statutory or otherwise by Tenant against Landlord concerning, arising out of or
relating to any matter relating to this Lease and all of the covenants and
conditions or any obligations, contractual, statutory, or otherwise set forth
herein, shall be limited solely and exclusively to an amount which is equal to
the lesser of (i) the interest of Landlord in and to the Building, and (ii) the
interest Landlord would have in the Building if the Building were encumbered by
third party debt in an amount equal to eighty percent (80%) of the then current
value of the Building (as such value is reasonably determined by Landlord). Any
judgments rendered against Landlord shall be satisfied solely out of proceeds of
sale of Landlord's interest in the Building. No other property or assets of
Landlord, or any member, officer, director, shareholder, partner, trustee,
agent, servant or employee of Landlord (the "Representatives") shall be subject
to levy, execution or other enforcement procedure for the satisfaction of
Tenant's remedies under or with respect to this Lease, Landlord's obligations to
Tenant, whether contractual, statutory or otherwise, the relationship of
Landlord and Tenant hereunder, or Tenant's use or occupancy of the Building.
Tenant further understands that any liability, duty or obligation of Landlord to
Tenant not existing or accrued, shall automatically cease and terminate as of
the date that Landlord or any of Landlord's Representatives no longer have any
right, title or interest in or to the Building. The provisions hereof shall
inure to Landlord's successors and assigns including any Lender. The foregoing
provisions are not intended to relieve Landlord from the performance of any of
Landlord's obligations under this Lease, but only to limit the personal
liability of Landlord in case of recovery of a judgment against Landlord; nor
shall the foregoing be deemed to limit Tenant's rights to

                                     - 47 -
<PAGE>

obtain injunctive relief or specific performance or other remedy which may be
accorded Tenant by law or under this Lease.

                  K.       MEMORANDUM OF LEASE.

                  Either party, at the request of the other, will execute and
record a memorandum of this Lease in the public recorder's office.

                  L.       NO WAIVERS.

                  Failure of Landlord to insist upon strict compliance by Tenant
of any condition or provision of this Lease shall not be deemed a waiver by
Landlord of that condition. No waiver by Landlord of any provision of this Lease
shall be deemed to be a waiver of any other provision hereof or of any
subsequent breach by Tenant of the same or any other provision. No provision of
this Lease may be waived by Landlord, except by an instrument in writing
executed by Landlord. Landlord's consent to or approval of any act by Tenant
requiring Landlord's consent or approval shall not be deemed to render
unnecessary the obtaining of Landlord's consent to or approval of any subsequent
act of Tenant, whether or not similar to the act so consented to or approved. No
act or thing done by Landlord or Landlord's agents during the Term of this Lease
shall be deemed an acceptance of a surrender of the Premises, and no agreement
to accept such surrender shall be valid unless in writing and signed by
Landlord. Similarly, this Lease cannot be amended except by a writing signed by
Landlord and Tenant. Any payment by Tenant or receipt by Landlord of an amount
less than the total amount then due hereunder shall be deemed to be in partial
payment only thereof and not a waiver of the balance due or an accord and
satisfaction, notwithstanding any statement or endorsement to the contrary on
any check or any other instrument delivered concurrently therewith or in
reference thereto. Accordingly, Landlord may accept any such amount and
negotiate any such check without prejudice to Landlord's right to recover all
balances due and owing and to pursue its other rights against Tenant under this
Lease, regardless of whether Landlord makes any notation on such instrument of
payment or otherwise notifies Tenant that such acceptance or negotiation is
without prejudice to Landlord's rights.

                  M.       SUCCESSORS AND ASSIGNS.

                  The conditions, covenants and agreements contained herein
shall be binding upon and inure to the benefit of the parties hereto and their
respective heirs, executors, administrators, successors and assigns.

                  N.       WAIVER OF JURY TRIAL; GOVERNING LAW.

                  LANDLORD AND TENANT HEREBY WAIVE ALL RIGHT TO TRIAL BY JURY IN
ANY CLAIM, ACTION, PROCEEDING OR COUNTERCLAIM BY EITHER LANDLORD OR TENANT
AGAINST EACH OTHER OR ANY MATTER ARISING OUT OF OR IN ANY WAY CONNECTED WITH
THIS LEASE, THE RELATIONSHIP OF LANDLORD AND TENANT, AND/OR TENANT'S USE OR
OCCUPANCY OF THE PREMISES.

                  This Lease shall be governed by the law of the State where the
Building is located. No conflicts of law rules of any state or country
(including, without limitation, the conflicts of law rules of the State in which
the Building is located) shall be applied to result in the application of any
substantive or procedural laws of any state or country other than the State in
which the Building is located. All controversies, claims, actions or causes of
action arising between the parties hereto and/or their respective successors and
assigns, shall be brought, heard and adjudicated by the courts of the
Commonwealth of Massachusetts, with venue in the County of Suffolk. Each of the
parties hereto

                                     - 48 -
<PAGE>

hereby consents to personal jurisdiction by the courts of the Commonwealth of
Massachusetts in connection with any such controversy, claim, action or cause of
action, and each of the parties hereto consents to service of process by any
means authorized by the law of the State in which the Building is located and
consent to the enforcement of any judgment so obtained in the courts of the
State in which the Building is located on the same terms and conditions as if
such controversy, claim, action or cause of action had been originally heard and
adjudicated to a final judgment in such courts. Each of the parties hereto
further acknowledges that the laws and courts of the State in which the Building
is located were freely and voluntarily chosen to govern this Lease and to
adjudicate any claims or disputes hereunder.

                  O.       EXHIBITS.

                  All exhibits attached to this Lease are a part hereof and are
incorporated herein by reference and all provisions of such exhibits shall
constitute agreements, promises and covenants of this Lease.

                  P.       CAPTIONS.

                  The captions and headings used in this Lease are for
convenience only and in no way define or limit the scope, interpretation or
content of this Lease.

                  Q.       COUNTERPARTS.

                  This Lease may be executed in one (1) or more counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.

                  R.       TIME OF ESSENCE.

                  Each of Tenant's covenants herein is a condition and time is
of the essence with respect to the performance of every provision of this Lease.

                  S.       SURVIVAL OF OBLIGATIONS.

                  Any obligations of Tenant and Landlord occurring prior to the
expiration or earlier termination of this Lease shall survive such expiration or
earlier termination.

                  T.       Intentionally Omitted.

                  U.       NO OPTION.

                  THE SUBMISSION OF THIS LEASE BY LANDLORD, ITS AGENT OR
REPRESENTATIVE FOR EXAMINATION OR EXECUTION BY TENANT DOES NOT CONSTITUTE AN
OPTION OR OFFER TO LEASE THE PREMISES UPON THE TERMS AND CONDITIONS CONTAINED
HEREIN OR A RESERVATION OF THE PREMISES IN FAVOR OF TENANT, IT BEING INTENDED
HEREBY THAT THIS LEASE SHALL ONLY BECOME EFFECTIVE UPON THE EXECUTION HEREOF BY
LANDLORD AND DELIVERY OF A FULLY EXECUTED LEASE TO TENANT.

                                     - 49 -
<PAGE>

                  V.       Intentionally Omitted.

                  W.       RIGHT OF LANDLORD TO PERFORM.

                  All covenants and agreements to be performed by Tenant under
any of the terms of this Lease shall be performed by Tenant at Tenant's sole
cost and expense and without any abatement of Rent. If Tenant shall fail to pay
any sum of money, other than Rent, required to be paid by it hereunder or shall
fail to perform any other act on its part to be performed hereunder, and such
failure shall continue beyond any applicable cure period set forth in this
Lease, Landlord may, but shall not be obligated to, without waiving or releasing
Tenant from any obligations of Tenant, make any such payment or perform any such
other act on Tenant's part to be made or performed as is in this Lease provided.
All sums so paid by Landlord and all reasonable incidental costs, together with
interest thereon at the prime rate of Fleet Bank, N.A. or any successor thereto,
plus three percent (3%) from the date of such payment by Landlord, shall be
payable to Landlord on demand and Tenant covenants to pay any such sums, and
Landlord shall have (in addition to any other right or remedy of Landlord) the
rights and remedies in the event of the nonpayment thereof by Tenant as are set
forth in this Lease.

                  X.       ACCESS, CHANGES IN PROJECT, FACILITIES

                                    (i)      Every part of the Building except
                  the inside surfaces of all walls, windows and doors bounding
                  the Premises (including exterior building walls, core corridor
                  walls and doors and any core corridor entrance), and any space
                  in or adjacent to the Premises used for shafts, stacks, pipes,
                  conduits, fan rooms, ducts, electric or other utilities, sinks
                  or other building facilities, and the use thereof, as well as
                  access thereto through the Premises for the purposes of
                  operation, maintenance, decoration and repair, are reserved to
                  Landlord.

                                    (ii)     Tenant shall permit Landlord to
                  install, use and maintain pipes, ducts and conduits within the
                  walls, columns and ceilings of the Premises.

                                    (iii)    Landlord reserves the right,
                  without incurring any liability to Tenant therefor, to make
                  such changes in or to the Building and the fixtures and
                  equipment thereof, as well as in or to the street entrances,
                  halls, passages, elevators, stairways and other improvements
                  thereof, as it may deem necessary or desirable.

                  Y.       IDENTIFICATION OF TENANT.

                                    (1)      If Tenant constitutes more than one
                  person or entity, (A) each of them shall be jointly and
                  severally liable for the keeping, observing and performing of
                  all of the terms, covenants, conditions and provisions of this
                  Lease to be kept, observed and performed by Tenant, (B) the
                  term "Tenant" as used in this Lease shall mean and include
                  each of them jointly and severally, and (C) the act of or
                  notice from, or notice or refund to, or the signature of, any
                  one or more of them, with respect to the tenancy of this
                  Lease, including, but not limited to, any renewal, extension,
                  expiration, termination or modification, of this Lease, shall
                  be binding upon each and all of the persons or entities
                  executing this Lease as Tenant with the same force and effect
                  as if each and all of them had so acted or so given or
                  received such notice or refund or so signed.

                                    (2)      If Tenant is a partnership (or is
                  comprised of two or more persons, individually and as
                  co-partners of a partnership) or if Tenant's interest in this

                                     - 50 -
<PAGE>

                  Lease shall be assigned to a partnership (or to two or more
                  persons, individually and as co-partners of a partnership)
                  pursuant to Article 16 hereof (any such partnership and such
                  persons hereinafter referred to in this Paragraph 30.Y. as
                  "Partnership Tenant"), the following provisions of this Lease
                  shall apply to such Partnership Tenant:

                                             (A)      The liability of each of
                           the parties comprising Partnership Tenant shall be
                           joint and several.

                                             (B)      Each of the parties
                           comprising Partnership Tenant hereby consents in
                           advance to, and agrees to be bound by, any written
                           instrument which may hereafter be executed, changing,
                           modifying or discharging this Lease, in whole or in
                           part, or surrendering all or any part of the Premises
                           to the Landlord, and by notices, demands, requests or
                           other communication which may hereafter be given, by
                           the individual or individuals authorized to execute
                           this Lease on behalf of Partnership Tenant under
                           Paragraph 30.W. above.

                                             (C)      Any bills, statements,
                           notices, demands, requests or other communications
                           given or rendered to Partnership Tenant or to any of
                           the parties comprising Partnership Tenant shall be
                           deemed given or rendered to Partnership Tenant and to
                           all such parties and shall be binding upon
                           Partnership Tenant and all such parties.

                                             (D)      If Partnership Tenant
                           admits new partners, all of such new partners shall,
                           by their admission to Partnership Tenant, be deemed
                           to have assumed performance of all of the terms,
                           covenants and conditions of this Lease on Tenant's
                           part to be observed and performed.

                                             (E)      Partnership Tenant shall
                           give prompt notice to Landlord of the admission of
                           any such new partners, and, upon demand of Landlord,
                           shall cause each such new partner to execute and
                           deliver to Landlord an agreement in form satisfactory
                           to Landlord, wherein each such new partner shall
                           assume performance of all of the terms, covenants and
                           conditions of this Lease on Partnership Tenant's part
                           to be observed and performed (but neither Landlord's
                           failure to request any such agreement nor the failure
                           of any such new partner to execute or deliver any
                           such agreement to Landlord shall terminate the
                           provisions of clause (d) of this Article 30(Y)(2) or
                           relieve any such new partner of its obligations
                           thereunder).

                                   ARTICLE 31.

                             RIGHT OF FIRST REFUSAL

         (a)      If this Lease shall be in full force and effect Landlord
shall, at such time as Landlord receives its first counter offer to or
acceptance of a lease proposal (the "Counter Offer") from a prospective tenant
to lease any portion of the fourth floor of the Building (the "Right of First
Refusal Space"), notify Tenant of the Counter Offer. Tenant shall have the
option, exercisable by notice to Landlord within five (5) business days after
receipt of Landlord's notice (the "Offer Notice"), to lease the Right of First
Refusal Space so offered (the "Offered Space") upon such terms and conditions as

                                     - 51 -
<PAGE>

are contained in this Lease except that (i) the Security Deposit shall be
proportionately increased and (ii) the per square foot Tenant Work Allowance for
the Offered Space shall be obtained by multiplying the per square foot Tenant
Work Allowance by a fraction, the numerator of which is the number of months
remaining in the initial term of this Lease at the time that Monthly Rent will
commence on the Offered Space and the denominator of which is the total number
of months in the initial term. Promptly after Tenant exercises this option (but
in no event later than twenty (20) days after the Offer Notice), the parties
shall enter into a supplemental agreement to this Lease incorporating the
Offered Space as part of the Premises.

         (b)      If Landlord has submitted to Tenant an Offer Notice and Tenant
shall notify Landlord that Tenant waives its right of first refusal as to such
Offered Space identified in the Offer Notice, or if Tenant is deemed to have
waived such right by failure to respond within the aforesaid five (5) business
day period (collectively, a "Waiver"), then Landlord shall have a period of nine
(9) months from the date of such Waiver to consummate a lease in respect of the
Offered Space. If a lease for the Offered Space is not executed within the nine
month period aforesaid, then the rights of first refusal accorded to Tenant in
this Section shall be deemed revived and reinstated with respect to any
subsequent desire of Landlord to lease the Offered Space subsequent to the
expiration of the nine month period aforesaid.

         (c)      Landlord shall also keep Tenant fully informed as to (i)
leasing activity as to any other space within the Building, including written
notice of lease proposals issued to other tenants or prospective tenants, and
(ii) the progress of negotiations as to the same.

         (d)      Notwithstanding anything herein contained to the contrary,
Tenant shall not have any of the rights contained in this Section for so long as
Tenant shall be in default beyond the expiration of applicable grace or cure
periods of any of the terms, conditions, covenants or provisions of this Lease.

                  IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties have duly executed this Lease with the Exhibits attached hereto, as
of the day and year first written above.

                                    LANDLORD:

                                    THREE HUNDRED THIRD STREET LLC

                                     - 52 -
<PAGE>

                             By:      MASSACHUSETTS MUTUAL LIFE
                             INSURANCE COMPANY,
                             Its Member, Duly Authorized

                             By:      CORNERSTONE REAL ESTATE
                             ADVISERS, INC.,
                                      its authorized agent

                                      By: /s/ David M. Romano
                                          ______________________________________
                                              David M. Romano
                                          ______________________________________
                                            [Printed Name and Title]
                                             VICE PRESIDENT
                                          ______________________________________

                                      Date: 9/25/03
                                            _________________________

                             TENANT:

                             ALNYLAM PHARMACEUTICALS, INC.

                                      By:  /S/ John G. Conley
                                           _______________________________
                                               John G. Conley
                                           _______________________________
                                             [Printed Name and Title]
                                              VP - Strategy & Finance/CFO
                                           _______________________________

                                      Date: 9/19/03
                                            _____________________________

                                     - 53 -
<PAGE>

                              Certificate of Tenant

                  I, Jeffrey M. Wiesen, Secretary/Assistant Secretary of Alnylam
Pharmaceuticals, Inc., Tenant, hereby certify that the officers executing the
foregoing Lease on behalf of Tenant is/are duly authorized to act on behalf of
and bind the Tenant.

(Corporate Seal)

                                             /s/ Jeffrey M. Wiesen
                                             Secretary/Assistant Secretary

Date:

                                     - 54 -
<PAGE>

                                    EXHIBIT A

                       Plan Showing Building and Premises

                  (Including Roof and Ground Floor Facilities)

                                     - 55 -
<PAGE>

                                    EXHIBIT B

                        300 Third Street -Landlord's Work

       BASE BUILDING CONSTRUCTION DOCUMENTS AND BASE BUILDING DESCRIPTION

                  PURSUANT TO PROVISIONS OF THE LEASE, LANDLORD WILL PROVIDE AND
PAY FOR, WITHOUT REIMBURSEMENT BY TENANT NOR INCLUSION IN OPERATING EXPENSES THE
BASE BUILDING SUBSTANTIALLY IN ACCORDANCE WITH ATTACHMENT I TO THIS EXHIBIT B,
DRAWINGS, SPECIFICATIONS AND ADDENDA (THE "BASE BUILDING CONSTRUCTION
DOCUMENTS") AND THE FOLLOWING BASE BUILDING NARRATIVE SUMMARY. ATTACHMENT 1 MAY
BE MODIFIED, AMENDED OR ADJUSTED, FROM TIME TO TIME, BY CHANGE ORDER OR
OTHERWISE, AS PERMITTED BY ARTICLE 5, PARAGRAPH A OF THE LEASE. EXCEPT AS
OTHERWISE PROVIDED WITHIN THIS LEASE EXHIBIT B, ALL SUPPLEMENTARY BUILDING
SYSTEM CONSTRUCTION TO SUPPORT LABORATORY OPERATIONS WITHIN THE PREMISES, ARE TO
BE PROVIDED BY TENANT.

Base Building Description:

300 Third Street contains 128,190 square feet of rentable floor area, 125,867
square feet of which will be available to accommodate first class executive
offices and biomedical laboratories, on four floors of the building.
Approximately 2,323 rentable square feet of accessory office / retail space is
available on the building's ground floor facing Third Street. The four floors of
office / laboratory space are constructed above a two level Parking Garage with
gate controlled, vehicular entrance and exit ways to / from Linskey Way. 300
Third Street has been built as a first class office / laboratory facility in
full compliance with all applicable governmental building codes. Landlord
represents that the Premises shall be treated as being located on the fifth and
sixth levels above grade for all purposes, including, without limitation,
storage of flammables and other materials under the state building code.

SITE DEVELOPMENT:

         a.       The perimeter of the 300 Third Street building site is
         improved with scored concrete sidewalks, decorative brick-paved
         pedestrian pathways, irrigated landscaped areas and site lighting in
         keeping with its urban environment.

         b.       Specimen trees and ground coverings complement the building's
         primary Third Street and Binney Street frontage as well as its Linskey
         Way parking facility access / egress points.

         c.       A pocket park with raised planting beds and seating areas has
         been constructed at the Third Street / Linskey Way corner.

         d.       The mid-block pass-through to the East of the building,
         providing access to the building's indoor bicycle parking area, is
         enhanced with brick screen walls, a serpentine brick-paved pathway,
         security lighting and tree plantings.

STRUCTURAL SYSTEM:

         a.       A two-story reinforced concrete Parking Garage (Levels Pl and
         P2), the lower level of which has been constructed with bituminous
         asphalt paving approximately 18" below sidewalk grade. Foundations are
         precast concrete piles with reinforced concrete tie and grade beams.

                                     - 56 -
<PAGE>

         b.       The four office / laboratory floors (Levels 01,02,03 and 04)
         above the Parking garage is structural steel braced-frame construction
         supporting composite reinforced concrete floors with a live load
         capacity of 100 pounds per square foot with a minimum flatness criteria
         of 3/16" per 10 feet.

         c.       The roof level is metal deck construction, a portion of which
         is structurally-reinforced to accommodate Tenant's future equipment
         dunnage. A portion of the roof area will be provided by Landlord, at
         its cost, with an enclosed penthouse to house Base Building and all
         building tenants' mechanical and electrical equipment installations. If
         required and as space allows, Tenant may at its cost and with
         Landlord's permission, expand the penthouse size to approximately 7,600
         square feet.

         d.       Floor-to-floor elevations of the office / laboratory floors
         are 13'-0".

BUILDING EXTERIOR:

         a.       The building's exterior walls are constructed with a
         combination of architectural precast concrete, glass fiber reinforced
         concrete ("GFRC"), composite metal panels and a glazed curtain-wall
         system.

         b.       Windows are "low E" insulated glass set in thermally broken
         aluminum frames.

         c.       Roofing is a direct-adhered, single ply EPDM membrane system
         applied over rigid insulation complying with energy conservation
         requirements of the Massachusetts State Energy Code, sixth edition.

         d.       Street level exterior entrance doors are glazed with stainless
         steel clad frames

LOADING DOCK:

         a.       The existing Loading Area shall be equipped with an exterior
         "scissor-lift" device to assist with truck-bed high on-loading and
         off-loading.

ELEVATORS:

         a.       Two electric-powered, geared-traction passenger elevators of
         3,500 pound capacity and 350 feet per minute travel speed serve the
         building's entrance lobby at Parking level PI and Office / Laboratory
         levels 01, 02, 03 and 04.

         b.       A third 4,500 pound hydraulic elevator unit with a travel
         speed of 150 feet per minute provides access between Parking Garage
         Levels PI and P2 and Office / Laboratory Levels 01, 02, 03 and 04 for
         building occupants using the Parking Garage facilities and for
         accessory freight connection to the building's truck dock.

INTERIOR FINISHES:

         a.       The main entrance lobby floor includes a dramatic
         terrazzo-type stone material with inset carpeting at elevators and
         carpeted walk-off areas at vestibules. Lobby walls are a combination of
         ornamental plaster with reveals and finished wood panels. The ceiling
         is coffered gypsum wallboard and acoustical tiles.

         b.       Acoustical ceilings at toilet rooms, locker/shower areas, and
         other building shell & core areas are to be 2' x 2' x 5/8" acoustical
         ceiling tile (moisture-resistant where applicable), similar to
         Armstrong Designer Series, set in 15/16" exposed metal grid. The
         ceiling system at the P-2 parking level is exterior grade lay-in
         acoustic panels.

         c.       Interior wall partitions are 5/8" gypsum wallboard on 35/8"
         metal studs (fire rating per Code); toilet rooms and core area
         mechanical shaft ways and rooms to be insulated full-height partitions
         (slab-to-slab). Interior surfaces of exterior building walls and tenant
         sides of building core walls to be 5/8" gypsum wallboard taped,
         spackled and ready to receive tenant's application of interior
         wall-covering materials.

                                     - 57 -
<PAGE>
         d.       Elevator lobby areas on multiple-tenanted floor levels 01, 02,
         03 and 04 are finished with building standard carpet and vinyl base.
         Concrete floors in Tenant fit-up areas are to be level, clean and ready
         to receive Tenant carpeting materials.

         e.       Exterior windows have prime-painted MDX window sills and
         perforated vertical window blinds.

         f.       Toilet Rooms/Locker Rooms: Ceramic tile is installed on all
         floors and wet walls of toilet rooms. Lavatory counters are Corian
         solid surfacing with under-slung bowls and full-height frame-less wall
         mirrors above the counters. Metal toilet enclosures are ceiling mounted
         with baked enamel finishes. Installation of Toilet and Locker Room
         accessories comply with requirements of the Massachusetts Architectural
         Access Board and ADA recommendations.

         g.       On multi-tenant floors, tenant entry doors are to be
         stain-grade solid core wood doors with KD hollow metal doorframes and
         building standard hardware sets.

SPECIALTIES AND EQUIPMENT:

         a.       A uniform Base Building graphics system, consisting of
         interior core area signage and a building directory is provided.

         b.       Garage Signage and striping is provided.

HEATING, VENTILATING & AIR CONDITIONING:

         a.       The Base Building is programmed for a lab/office split over
         125,867 sf of the building's four floors. Estimated Lab area is 94,400
         rsf and the Office area is 31,467 rsf. The building is to be provided
         with three complementary HVAC systems, nos 1, 2 and 3.

         1.       HVAC System No 1: The building's office and core areas will be
                  served by one 65,000 cfm, 15% outside air, package
                  evaporative-cooled air conditioning unit mounted on the roof.

         Office Area Design Parameters:

                  a)       20 CFM of outside air per person based upon one
                           person per 150 rsf.

                  b)       Unit is capable of delivering 1.25 CFM/SF at 55
                           degrees F supply air temperature.

                  c)       Units have supply air and return air capabilities.

                  d)       Summer indoor design condition is 75 degrees F dry
                           bulb 50%, relative humidity at 88 degree F dry bulb,
                           73 degrees F wet bulb outdoor condition.

         2.       HVAC Systems 2 and 3: The building's laboratory areas will be
                  served by two (2) 100,000 CFM, 100% outside air, air handling
                  units located on the roof. The chilled water plant consists of
                  two (2) 700 ton water cooled chillers with associated cooling
                  towers. The heating plant shall consist of three (3) 190
                  Boiler Horsepower gas-fired hot water boilers. This chiller
                  plant and heating plant will be located within a mechanical
                  penthouse at the roof level.

         Lab Area System Design Parameters:

                  a.       Units are capable of delivering 2 CFM/SF of 100%
                           outdoor air.

                  b.       Lab area controls are variable air volume type.

                  c.       The chiller plant shall provide 15% spare capacity
                           for tenant use. Additional chilled water shall be
                           metered and Tenant shall be charged for consumption.

                  d.       Summer indoor design condition is 75 degrees F dry
                           bulb, 50% relative humidity at 88 degree F dry bulb,
                           73 degrees F wet bulb outdoor conditions.

                  e.       Winter indoor design condition is 72 degrees F dry
                           bulb at 9 degrees F dry bulb outdoor condition.

         3.       The office and laboratory system shall have the vertical
                  supply air, chilled water and hot water risers installed with
                  valves and caps at the building core for Tenant access. The
                  office system shall have the return air shaft ready for Tenant
                  use. The office system shall have the return air shaft ready
                  for Tenant use. All distribution required for Tenant supply
                  and return air, chilled water and

                                     - 58 -
<PAGE>

                  hot water shall be the responsibility of the Tenant. Refer to
                  the Base Building Construction Documents for supply air
                  allocations by floor.

         b.       The Base Building also supports the construction of up to four
         additional 6' x 8' enclosed exhaust shafts (Level O-1 to Roof) to
         accommodate non-exclusive tenant exhaust ducting from laboratories,
         fume hoods and animal facilities. Landlord shall construct these shafts
         with light-gauge metal framing and gypsum wallboard materials; Tenant
         will be responsible for all ductwork required within the shafts except
         for ductwork associated with HVAC system Nos 1, 2 and 3 described above
         which shall be Landlord's work. Tenant shafts in addition to, or in
         replacement of, those described above may be constructed by Tenant,
         with prior written approval of Landlord.

         c.       Air distribution (supply and return) systems, diffusers,
         registers, grilles, controls, fan-powered perimeter boxes, interior
         variable air volume boxes, laboratory hood supply, exhaust and special
         systems along with all hot water, cold water and miscellaneous piping
         for Tenant requirements within, or without, the Premises are to be
         provided by Tenant.

         d.       Heating, cooling and ventilation systems for building core
         areas, including mechanical rooms, elevator machine rooms, toilet rooms
         and electric rooms, are provided by Landlord. Bicyclist shower and
         locker facilities on level P1 are served by separate AC units installed
         near the Truck Dock area. Unit space heaters ARE provided in the
         ceiling plenum above the P-2 parking level to complement the Tenant's
         first floor heating system during cool weather periods.

         e.       The Base Building HVAC system has a fully automated, direct
         digital control ("DDC") energy management system consisting of a
         central host station, controllers and network communications components
         with system capacity to add-on tenant-area monitoring / control points
         provided by Tenant.

         f.       Location, height, size and noise output of the Base Building
         rooftop mechanical equipment is in compliance with City of Cambridge
         guidelines. Plans and specifications, including equipment sound
         generation characteristics for additional mechanical equipment which
         Tenant may desire to install on the building roof shall be submitted
         for review and approval to Landlord's Architect. Excess Tenant
         equipment noise output may be permitted in proportion to Tenant share
         of rentable area in the building and shall be coordinated with Base
         Building equipment so as to not exceed the levels allowed. Tenant
         shall, at Tenant expense, add sound attenuation equipment to the new
         Tenant equipment and to the Base Building equipment as may be needed to
         accommodate its equipment needs within the constraints of the Cambridge
         Noise Ordinance.

PLUMBING:

         a.       The building is served by a 74 psi 4-inch domestic water
         service from Binney Street which will be separated into potable water
         and non-potable water branches, each equipped with backflow preventers,
         at the street-level water room (non-potable water distribution as
         needed from the street-level water room to laboratory areas on by
         Tenant). Backflow preventers are also installed at each mechanical
         equipment connection, as required by Code.

         b.       Toilet Rooms are sized for one person per 175 sq ft of
         occupied area (50% men / 50% women).

         c.       1 1/2 inch valved-and-capped potable cold-water sources are
         provided, for supplemental Tenant connection, at two core-area
         wet-column locations on each floor.

         d.       The building is served by a 6 inch sanitary sewer line.
         Separate sewer (lab waste) lines, if needed for conducting laboratory
         waste material from the Tenant Premises to grade, can be installed by
         Tenant at Tenant cost.

         e.       A 6-inch natural gas service line enters the building from
         Linskey Way to serve the Base Building's rooftop air conditioning units
         (morning warm-up). An 8-inch high-pressure gas line shall enter the
         building from Linskey Way to serve the Base Building boilers. NStar Gas
         Company shall leave a cap at the exterior of the building at the same
         location for future Tenant use including Tenant boilers, water heaters,
         generators, laboratory gas outlets and equipment. Tenant shall make
         separate metering and payment arrangements with NStar Gas Company.

                                     - 59 -
<PAGE>

FIRE PROTECTION:

         a.       Building floors are provided with risers and cross-mains to
         accommodate an Ordinary Hazard Group II (up to 0.20 gpm per sf density)
         automatic wet pipe sprinkler protection system. The Parking Garage is
         equipped with a fully operational automatic, dry-pipe sprinkler
         protection system. Sprinkler protection is provided in all electric
         rooms, telephone rooms and elevator pits as required by code.

         b.       Tenant premises have been provided with a sprinkler
         distribution system including upturned sprinkler heads on all floors.
         Completion of the system, including changes to the installed
         distribution system and down-turning the installed heads and adding
         heads and branch lines, as required for Tenant occupancy requirements,
         is to be provided by Tenant in connection with fit-up of the floors.
         Building lobbies and common areas have concealed heads, centered on
         ceiling grids.

         c.       The building is provided with a 500 gpm, 40-psi, electric fire
         pump. Combination standpipe/sprinkler risers are provided in each
         egress stairway with fire department hose valves at each floor. A
         backflow preventer is provided at fire service building entrances.

ELECTRICAL:

         a.       The facility is served by dual, 15 kilovolt underground NStar
         primary service feeders running to 15 KV switch gear with automatic
         transfer between feeders, and a primary / secondary transformer
         (NStar-owned) at level Pl.

         b.       Secondary service consists of two switchboards located in the
         level P1 Electric Room. One switchboard is sized at 3,000 ampere,
         480/277 volt, 3 phase, 4 wire to serve two metered bus duct risers for
         tenant loads. The second switchboard is a metered switchboard sized at
         3,000 ampere, 480/277 volt, 3 phase, 4 wire to serve the Base Building
         loads.

         Office Tenant Area Design Parameters:

                           i.       2.0 watts/sf for Lighting

                           ii.      4.0 watts/sf for Office Power

                           iii.     2.0 watts/sf for HVAC Equipment

                           iv.      8.0 watts/sf Total

         Lab Tenant Area System Design Parameters:

                           i.       2.0 watts/sf for Lighting

                           ii.      10.0 watts/sf for Lab Power

                           iii.     3.0 watts/sf for HVAC Equipment

                           iv.      15.0 watts/sf Total

         c.       Total combined electric service for all base building and
         tenant areas is based on 29.8-volt amperes per square foot, available
         at the building's main switchboard.

         d.       A bus duct riser shall be provided from the Level P-1 Electric
         Room to electric closets on each office floor to serve up-to three
         tenants per floor. Tenants will be individually responsible for
         installing a bus disconnect switch, an electrical consumption metering
         device, panelboards and all electrical devices and equipment needed for
         occupancy of the premises, including connection of all Tenant-installed
         equipment connection to Tenant's metering device and connection of the
         metering device to Landlord's computer-based energy monitoring and
         billing system. Landlord shall provide Tenant with a monthly bill for
         electric energy consumed by Tenant.

         e.       Base Building lighting fixtures are recessed parabolic
         fluorescent and cove lighting (T8 lamps) types with motion-actuated
         switching in toilet rooms. Level P1 lobby areas have recessed metal
         halide down lighting and recessed cove fluorescent fixtures; exit
         stairwells have surface-mounted linear fluorescent fixtures; general
         mechanical, service and storage areas have chain-hung industrial
         fluorescent fixtures. Site and parking lighting are exterior grade
         metal halide type. Subject to the review and approval by Landlord,
         Tenant will not be required to use Building Standard fixtures in
         Tenant's space.

         f.       Building core areas are provided with duplex convenience power
         outlets as shown on the plans. Emergency lighting requirements are
         provided via bodine-ballasted standard lights in the Entrance Lobby and
         standard battery pack units elsewhere.

                                     - 60 -
<PAGE>

TELEPHONE & DATA:

         a.       The building is designed to accommodate redundant incoming
         tel/data communication services (hard- wire or fiber-optic) from
         multiple competitive service providers. Tenants are responsible for
         making connection service, metering and billing arrangements with
         selected communication providers.

         b.       Two onsite telephone-data manhole locations are provided
         immediately adjacent to the Third Street property line with multiple
         underground conduit banks to the building's main Telephone Room at
         level P1.

         c.       Telephone floor sleeves for tenant communication installation
         requirements, are run from the level P1 Telephone Room to telephone
         closets on each office floor. Tenants are expected to provide separate
         telephone / data closets within tenant premises to house all required
         tenant patch-panels, switching devices and communication equipment.

FIRE ALARM:

         a.       The building is protected by a multiplex addressable fire
         alarm system including detection and alarm annunciation devices
         centered on a fire alarm control panel located in the P1 lobby area.

         b.       Core area smoke detectors, pull stations, and horn / strobe
         units are installed in compliance with all applicable codes and
         recommendations of the Americans with Disabilities Act pursuant to
         National Fire Protection Association Manual 72. Complementary fire
         protection and alarm systems within each tenant area are to be provided
         by Tenant in connection with fit-up of the Premises.

SECURITY:

         a.       Pedestrian and vehicular access to the building is controlled
         through the use of electronic locks and gates with programmable
         proximity card readers. Tenant personnel, with appropriate security
         authorization, will have access on a 24 hour / 7 day basis. The bicycle
         storage area, shower facilities and service entrances are included in
         the building's access control system.

         b.       The Base Building security system incorporates the use of
         burglar alarms on all perimeter doors and other specified areas of the
         property.

         c.       Surveillance cameras are integrated into the security system,
         covering the parking garage, perimeter access points, the service /
         truck dock entrance, and the elevator lobbies on levels P-1 and P-2.

         d.       During business hours, the hub of the building's security
         system is located at the main lobby's security desk. After hours, and
         on weekends and holidays, calls and alarms are forwarded to a security
         and monitoring service.

         e.       The Base Building card access, burglar alarm and surveillance
         system is expandable, to incorporate Tenant provided internal security
         system add-ons.

         f.       The Base Building can accommodate the installation, by the
         Tenant, of card access systems at primary entries and in the elevators
         - including card readers and traveling cables in all elevators.

LABORATORY SPECIFIC INFORMATION:

         a.       Modification of Base Building systems to accommodate and / or
         house laboratory chemicals or specimens; clean rooms; temperature,
         light, noise or vibration-controlled areas; hazardous / radioactive
         materials and gas storage rooms; pure water systems; animal holding
         areas, tel/data rooms, UPS rooms; halon or pre-action fire suppression
         systems shall be at Tenant cost.

         b.       Base Building includes construction of an approximately 12' x
         12' acid neutralization room on the building's P-2 parking level for
         use by all building tenants. This room shall be constructed of durable
         material such as CMU and fully insulated and equipped with securable
         hardware on an insulated hollow metal door. Tenants using the room
         shall provide all waste neutralization equipment and MEP services

                                     - 61 -
<PAGE>

         required by the equipment and to condition the space. The room will
         include an adequate waste line connecting from the room to the exterior
         (street-level) lab waste line in compliance with MWRA requirements
         including exterior sampling ports.

         c.       Space to install a gas-fed standby generator together with
         requisite structural supports can be made available to Tenant on the
         building roof level.

         d.       Vibration isolation for Tenant's laboratory equipment may be
         accommodated via modification of the Base Building structural systems
         at Tenant expense.

IN THE EVENT OF INCONSISTENCY BETWEEN THE ABOVE BASE BUILDING DESCRIPTION AND
THE BASE BUILDING CONSTRUCTION DOCUMENTS LISTED IN ATTACHMENT NO 1 TO THIS
EXHIBIT B, THE CONSTRUCTION DOCUMENTS SHALL PREVAIL.

                                     - 62 -
<PAGE>

                           Attachment No 1 - Exhibit B

                             Construction Documents

                                     - 63 -
<PAGE>

                                    EXHIBIT C

                        300 Third Street - Tenant's Work

                          Work Letter for Tenant Fit Up

I.       PLANS, WORKING DRAWINGS AND SPECIFICATIONS

A.       Subject to the reasonable approval of Landlord, Tenant shall, at
Tenant's sole expense, retain the services of a registered professional
architect ("Tenant's Architect") to prepare the documents described herein and
require Tenant's Architect to conditionally grant full rights for Landlord's use
of such documents in the event of a Tenant default under the Lease. As of the
date hereof, Landlord has approved Olson Lewis, Boston, Mass. as Tenant's
Architect. In connection therewith, all mechanical, electrical, plumbing and
fire protection engineering and all structural engineering (if any) shall be
performed, respectively, at Tenant's sole expense, by AHA Consultants,
Lexington, Mass and by LCI Consultants, Cambridge Mass. ("Tenant's Engineering
Consultants"). Tenant's Architect shall coordinate all work by Tenant's
Engineering Consultants such that the Plans and the Working Drawings (both
defined below) are a seamless set of design and construction documents issued by
Tenant's Architect.

B.       No later than August 1, 2003 , Tenant shall submit to Landlord its
Design Control Plans (the "Plans"), substantially complete in all respects for
each floor of the Premises consisting of one (1) set of reproducibles and two
(2) sets of prints illustrating the work proposed to be done by Tenant (as
approved by Landlord, the "Tenant's Work"). The Plans shall include:

         1.       Partition layout and door locations,

         2.       Power and telephone outlet plans,

         3.       Preliminary furniture and equipment layouts,

         4.       Finishes schedule,

         5.       Reflected ceiling plan and other plans which cumulatively show
                  the anticipated location of the ceiling grid, light fixtures,
                  HVAC supply diffusers and return air grilles, sprinkler heads,
                  smoke and fire detectors, exit signs, speakers and all other
                  items as needed for proper engineering of the Premises,

         6.       Wall elevations, sections and details including direct
                  entrances from public areas into the Premises,

         7.       Tenant's progress set of electrical, HVAC, mechanical and
                  plumbing design criteria including single-line drawings as
                  appropriate, locations of special HVAC and electrical
                  apparatus, a preliminary electrical load summary, special
                  heating, ventilating and air conditioning equipment as needed,
                  concentrated file and/or library structural loads (if any) and
                  any other equipment or systems which may require modification
                  of the structural, mechanical, fire protection, plumbing,
                  electrical or life safety components of the building,

         8.       Specific identification of work items and equipment which
                  require long-lead delivery times in order to achieve
                  completion of Tenant's Work without delay.

The Plans shall be fully coordinated with Lease Exhibit B, Base Building
Construction Documents, and shall comply with all applicable governmental laws,
ordinances, building codes, orders, regulations and restrictions and property
insurance requirements.

C.       Within ten (10) Business Days following receipt of the Plans, Landlord
shall reasonably review same for compatibility with Landlord's Work, including
but not limited to Base Building systems or as otherwise provided in Exhibit B,
and provide to Tenant a letter of comments. If Landlord observes discrepancies
with such, it shall, within said thirteen (13) Business Day review period, so
notify Tenant who shall promptly correct the Plans to bring same into compliance
and resubmit to Landlord for review.

D.       Based upon, and within twenty (20) Business Days following Landlord's
initial response to Tenant's Plans submission, Tenant shall, at its sole
expense, prepare and submit to Landlord the architectural, HVAC, mechanical,
electrical, plumbing and all other construction drawings and specifications (the
"Working Drawings") necessary to perform all of Tenant's Work.

E.       Within ten (10) Business Days following receipt of the Working
Drawings, Landlord shall reasonably review same for substantial consistency with
the approved Plans and shall, in writing, approve portions of the Working
Drawings which reasonably conform to the Plans and disapprove those portions
which do not so conform, specifying the reasons for such disapproval. Tenant
shall, at its sole expense, promptly correct the Working Drawings to conform to
the approved Plans and resubmit to Landlord for review and approval.

                                     - 64 -
<PAGE>

F.       Simultaneously with Tenant submission to Landlord of the Working
Drawings, Tenant shall prepare and submit to Landlord, for Landlord's review and
approval:

1.       An itemized statement of the Total Cost of Tenant's Work, as defined in
Section IV (A) of this Exhibit C, to prepare the Premises in accordance with the
approved Working Drawings along with any costs needed to modify the Base
Building to accommodate Tenant's Work (the "Cost Proposal"),

2.       A copy of a building permit issued by the City of Cambridge for
Tenant's Work proposed to be performed, if obtainable,

3.       The names, and addresses for all contractors which Tenant proposes to
utilize to perform Tenant's Work,

4.       Certificates, issued by insurance companies licensed to do business in
Massachusetts, evidencing that worker's compensation, public liability and
builder's risk property insurance policies are in force and will be maintained
by all contractors having contracts of Twenty-Five Thousand Dollars ($25,000) or
more proposed by Tenant to perform Tenant's Work, with Landlord and Landlord's
construction lender named as additional insured parties,

5.       If any penetrations of the roof, or of the exterior skin of the
building, is required to complete the Work, evidence of contractors'
qualifications to perform such work with, in each instance, written
certification, reasonably acceptable to Landlord, that the watertight integrity
of the Building will not be compromised upon completion,

6.       If Tenant's general contractor for Tenant's Work is a construction
company other than Landlord's Base Building Contractor, a written summary
outlining arrangements made by Tenant's contractors (including furniture,
fixture and equipment installers) with Landlord's Base Building Contractor, for
access to the building; use of elevators if, and as, available; police details;
providing temporary utilities and appropriate security services during Tenant's
Work; coordinating inspections by governmental officials; scheduling deliveries;
removing debris; cleaning; temporary shutdowns; and all other tasks which will
be needed to coordinate the activities of separate general contractors working
within the building, provided that Landlord agrees to cooperate in facilitating
such coordination,

7.       A schedule for the proposed Tenant's Work, fully coordinated with, and
imposing no delays or cost penalties upon, Landlord's schedule for constructing
the Base Building pursuant to Lease Exhibit B,

8.       Copies of Tenant's construction agreements with its contractors and
evidence of bonding for Tenant's Work satisfactory to Landlord,

9.       Five (5) sets of the Working Drawings.

G.       In the event that any specific item of the Cost Proposal, or any other
submittal made pursuant to paragraph (I)F above, is unsatisfactory to Landlord
because, in Landlord's reasonable opinion, it is not in compliance with Section
IV(A) of this Exhibit C, Landlord shall provide Tenant with written notification
of such within fifteen (15) Business Days after Landlord's receipt of the Cost
Proposal and any other submittals made pursuant to paragraph (I)F above. Tenant
shall negotiate in good faith with parties responsible for such unsatisfactory
portions of the submittal and, failing resolution of the matters in question,
shall submit a revised Cost Proposal, and / or any other submittals, for
Landlord's review. Both parties shall use diligent efforts to complete this
review procedure within fifteen (15) Business Days following Tenant's first
submission of its Cost Proposal to Landlord.

Within fifteen (15) Business Days following receipt of the Cost Proposal,
Landlord shall notify Tenant, in writing, of either:

1.       its acceptance of the entire Cost Proposal as modified by any
supplementary prices or information obtained pursuant to this Section G, or,

2.       its notification pursuant to the preceding paragraph that such Cost
Proposal is not in compliance with this Exhibit C.

If Landlord fails to so notify Tenant within the fifteen (15) Business Day
period specified above, then Tenant shall provide written notification to
Landlord of such failure and, in the event Landlord fails to respond to Tenant
within five (5) Business Days following receipt of said notification, Landlord
shall be deemed to have accepted Tenant's submittal in its entirety and
authorized Tenant to proceed with Tenant's Work.

H.       Approval by Landlord of the Plans, the Working Drawings or the Cost
Proposal shall not be deemed to mean approval of structural capacity, size of
ducts and piping, adequacy of electrical wiring, system equipment capacities or
any

                                     - 65 -
<PAGE>

other technical matter relating to Tenant's Work. Such approvals shall not
relieve Tenant of responsibility for proper design and construction of Tenant's
Work in compliance with all applicable governmental laws, ordinances, building
codes, orders, regulations and restrictions and insurance underwriter
requirements.

I.       Tenant shall, at its sole expense, retain the services of Tenant's
Architect and Tenant's Engineering Consultants to monitor Tenant's Work pursuant
to Attachment I hereto.

J.       In order to facilitate Landlord's review of the submitted Plans and the
Working Drawings, Tenant shall deliver 60 percent "progress prints" of each to
Landlord which Landlord may review for the benefit and guidance of Tenant,
within five (5) Business Days of receipt.

II.      TENANT'S WORK AND CHANGES IN TENANT'S WORK

A.       Tenant's Work. Landlord and Tenant acknowledge that Landlord's Base
Building Construction Schedule includes an anticipated Tenant's Work
commencement date of 75 days following the full execution of the Lease. Landlord
shall cause the Base Building Contractor to periodically update such Schedule
during the course of Landlord's Work and Landlord shall deliver its most current
update to Tenant at the time of Landlord's approval of the Working Drawings
pursuant to paragraph 1(E).

Tenant shall be fully responsible for all matters that must be accomplished to
substantially complete Tenant's Work in accordance with this Exhibit C
including, without limitation, filing plans and other pertinent documentation
with the proper governmental authorities; obtaining all necessary building
permits and occupancy certificates; promptly removing, or bonding, any
mechanics, materialmen and like liens from the public record; supervising all
details of Tenant's Work; expending funds for overtime labor as needed; paying
contractors and subcontractors; maintaining harmonious labor relations between
Tenant contractor's work trades and those employed by Landlord's contractors and
any separate contractors; promptly removing, repairing and /or restoring damaged
, lost or destroyed work; removing Tenant's contractors' debris from the
building; payment of Tenant's Architect and Tenant's Engineering Consultants
fees, insurance costs, legal and brokerage fees, if any, costs of utilities
consumed during the Work, filing and permit fees and the like.

B.       Changes to Tenant's Work: Tenant may, at Tenant's sole responsibility
for all costs associated therewith, by written notification to Landlord, request
changes to the approved Plans or to the approved Working Drawings or to Tenant's
Work already installed (the "Change Proposal"). Such notification shall be
accompanied by a summary of the additional costs, or savings, involved with the
proposed change, an estimate of the period of time by which the date of
substantial completion of Tenant's Work will be affected by the change and an
indication of impacts, if any, upon Landlord's cost and completion schedule for
the Base Building Construction, it being understood that, in no instance shall
Landlord be obligated to approve a Tenant Change Proposal which would either (i)
increase the cost of Landlord's Work (unless Tenant agrees to pay such
additional costs) or (ii) delay the Substantial Completion Date of Landlord's
Work.

Landlord's review and approval of each such Change Proposal shall be conducted
pursuant to paragraphs I (G) and I (H) provided however that if Landlord fails
to respond in writing to Tenant's submittal of any specific Change Proposal
within ten (10) Business Days of receipt, such Change Proposal shall be deemed
to be approved in all respects by Landlord and Tenant shall be authorized to
make the change.

III.     SCHEDULE

A.       Summary of dates and durations contained within Sections I and II of
this Exhibit C, all subject to Force Majeure provided that Landlord shall not be
required to respond prior to the dates set forth in paragraph I above.

         Tenant submits Plans to Landlord                     Complete

         Landlord responds to Plans                           Complete

         Tenant submits Working Drawings to Landlord:         October 10, 2003

         Landlord responds to Working Drawings                October 24, 2003

         Tenant submits Cost Proposal to Landlord:            October 24, 2003

                                     - 66 -
<PAGE>

         Landlord responds to Cost Proposal:                  November 3, 2003

         Anticipated date of commencement of Tenant's
                  Work in the Premises:                       November 3, 2003

         Tenant substantially completes Tenant's Work         March 16, 2004

IV.      TOTAL COST AND PAYMENTS

A.       The term "Total Cost", as used in this Exhibit C, shall mean the sum of
all costs included in Tenant's Cost Proposal reviewed by Landlord pursuant to
paragraphs I (G) and I (H), plus any additional costs due to Change Proposals
approved by Landlord pursuant to paragraph II (B) plus any additional
out-of-pocket costs actually incurred by Tenant to design and construct Tenant's
Work including, without limitation:

         1.       construction and construction management costs as defined in
                  Article 6 of the Landlord's Construction Agreement with the
                  Base Building Contractor, Attachment 2 hereto,

         2.       costs of general contractor's payment, performance and lien
                  bond premiums,

         3.       permits and fees as required by governmental authorities
                  having jurisdiction over Tenant's Work,

         4.       insurance premiums for liability, worker compensation and
                  property damage coverages,

         5.       architects and engineers fees as required to prepare the Plans
                  and the Working Drawings and monitor the Tenant's Work,
                  including tasks listed in paragraphs I(A), I(E) and I(I),

         6.       expenses of on-site, and off-site, material inspections and
                  tests.

B.       Landlord shall provide Tenant with an allowance of ninety dollars
($90.00) per square foot of rentable area of the Premises (including the acid
neutralization and rooftop facilities) ("Tenant Work Allowance") as partial
reimbursement to Tenant for its Total Cost to complete Tenant's Work.

C.       Periodically, but not more often than monthly, Tenant shall prepare and
submit to Landlord, certified by Tenant's Architect, a cost summary of all costs
incurred by Tenant during the preceding month to prepare the Premises for
occupancy pursuant to the approved Working Drawings, along with a current
reconciliation of Tenant's Total Cost as outlined in paragraph IV (A) and the
Tenant Work Allowance, as outlined in paragraph IV (B), a summary of monies
spent to-date and previous payments made, copies of all contractor payment
applications, invoices and the like received by Tenant, retainage amounts
withheld, lien waivers from all contractors providing labor, materials or
services for Tenant's Work and any further cost backup / information as Landlord
may reasonably request, utilizing accounting and cost control methods reasonably
acceptable to Landlord.

D.       In order to receive payment of the Tenant Work Allowance pursuant to
paragraph IV(B) Tenant shall provide to Landlord the following and Landlord
shall pay the Tenant Work Allowance within ten (10) business days thereafter:

         1.       a certificate of Tenant's Architect that Tenant's Work has
                  been substantially completed in accordance with the Working
                  Drawings approved by Landlord;

         2.       evidence satisfactory to Landlord, including without
                  limitation, final lien waivers, that all labor and materials
                  included in Tenant's Work has been paid in full;

         3.       a certificate of occupancy issued by the City of Cambridge
                  with respect to the Premises;

         4.       such other documentation, if any, as may be reasonably
                  required by Landlord;

         5.       a Notice of Substantial Completion, prepared by Tenant
                  pursuant to Massachusetts General Laws, chapter 254, and
                  recorded by Tenant's Contractor at Middlesex South Registry.

E.       Landlord shall also provide Tenant with a Building review allowance of
ten cents ($0.10) per square foot of rentable area of the Premises ("Tenant
Review Allowance") for costs associated with the review of Landlord's Work. The
Tenant Review Allowance shall be paid together with the final installment of the
Tenant Work Allowance.

V.       TENANT'S AND LANDLORD'S REPRESENTATIVES

A.       Tenant and Landlord each hereby designate a sole construction
representative with respect to matters set forth in this Exhibit C Work Letter
for Tenant Fit Up and such person shall have full authority and responsibility
to act on behalf of Tenant and / or Landlord as required herein.

Tenant's Construction Representative: Richard Priester or any replacement
designated in writing by Tenant

                                     - 67 -
<PAGE>

Landlord's Construction Representative: William J Byrne, Jr. or any replacement
designated in writing by Landlord

Attachment 1:     Monitoring of Tenant's Work

                                     - 68 -
<PAGE>

             Attachment 1 to Exhibit C Work Letter for Tenant Fit Up
                           Monitoring of Tenant's Work

1.       Tenant's Architect and Tenant's Engineering Consultants responsible for
preparing the Working Drawings shall monitor, by regular visits to the building,
the progress of the Tenant's Work to ensure conformance to the Working Drawings.
A report of each such visit including a listing of all items of unacceptable
work observed during such visits, along with copies of all correspondence
between Tenant and Tenant's Architect and Tenant's Engineering Consultants,
shall be submitted to Tenant's contractors and to Tenant and Landlord's
Representatives.

2.       The appropriate Tenant's Architect and/or Tenant's Engineering
Consultant shall review all contractor shop drawings and submittals pertaining
to Tenant's Work and require Tenant's contractors resubmit same until an
approved set is obtained.

3.       The appropriate Tenant's Architect and/or Tenant's Engineering
Consultant shall prepare any clarifying drawings and supplementary information
as may be needed to explain the intent of the Working Drawings to Tenant
contractors.

4.       The appropriate Tenant's Architect and/or Tenant's Engineering
Consultant shall review and certify the Tenant's contractors monthly
applications for payment.

5.       Tenant's Architect shall certify as to the Date of Substantial
Completion of Tenant's Work. Within ten (10) business days thereafter, the
appropriate Tenant's Architect and/or Tenant's Engineering Consultant shall
prepare, and issue, a comprehensive listing of incomplete and unacceptable items
of work (the so-called "punch list") for approval by Tenant and Landlord. After
approval by Tenant and Landlord, the appropriate Architect or Engineer shall
monitor punch list items until completion which will, in all events, occur no
later than thirty (30) days following Substantial Completion of Tenant's Work.

6.       Following completion of all items contained with the so-called punch
list, Tenant's Architect shall certify as to the Date of Final Completion of the
Tenant's Work and issue its Final Certificate For Payment to Tenant's
contractors

7.       Tenant's Architect shall monitor Contractor's completion of as-built
drawings for the Tenant's Work and deliver a reproducible set of same to Tenant
and to Landlord with Architect's Final Certificate for Payment.

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                                    EXHIBIT D

                        Building's Rules and Regulations
                          and Janitorial Specifications

                  1.       The sidewalks, entrances, passages, courts,
elevators, vestibules, stairways, corridors or halls of the Building shall not
be obstructed or encumbered or used for any purpose other than ingress and
egress to and from the premises demised to any tenant or occupant.

                  2.       No awnings or other projection shall be attached to
the outside walls or windows of the Building without the prior consent of
Landlord. No curtains, blinds, shades, or screens shall be attached to or hung
in, or used in connection with, any window or door of the premises demised to
any tenant or occupant, without the prior consent of Landlord. Such awnings,
projections, curtains, blinds, shades, screens or other fixtures must be of a
quality, type, design and color, and attached in a manner, approved by Landlord.

                  3.       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 premises demised to any tenant or occupant of the
Building except as provided in the Lease. Interior signs on doors and directory
tables, if any, shall be of a size, color and style approved by Landlord.

                  4.       The sashes, sash doors, skylights, windows, and doors
that reflect or admit light and air into the halls, passageways or other public
places in the Building shall not be covered or obstructed, nor shall any
bottles, parcels, or other articles be placed on any window sills.

                  5.       No show cases or other articles shall be put in front
of or affixed to any part of the exterior of the Building, nor placed in the
halls, corridors, vestibules or other public parts of the Building.

                  6.       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.

                  7.       Intentionally Omitted.

                  8.       No cooking, except for microwave cooking, shall be
done or permitted in the Building by any tenant without the approval of the
Landlord.

                  9.       No space in the Building shall be used for
manufacturing, for the storage of merchandise, or for the sale of merchandise,
goods, or property of any kind at auction, without the prior consent of
Landlord.

                  10.      No tenant shall make, or permit to be made, any
unseemly or disturbing noises or disturb or interfere with other tenants or
occupants of the Building or neighboring buildings or premises whether by the
use of any musical instrument, radio, television set or other audio device,
unmusical noise, whistling, singing, or in any other way. Nothing shall be
thrown out of any doors or window.

                  11.      No additional locks or bolts of any kind shall be
placed upon any of the doors or windows, nor shall any changes be made in locks
or the mechanism thereof. Each tenant must,

                                     - 70 -
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upon the termination of its tenancy, restore to Landlord all keys of stores,
offices and toilet rooms, either furnished to, or otherwise procured by, such
tenant.

                  12.      All removals from the Building, or the carrying in or
out of the Building or the premises demised to any tenant, of any safes,
freight, furniture or bulky matter of any description must take place at such
time and in such manner as Landlord or its agents may determine, from time to
time. Landlord reserves the right to inspect all freight to be brought into the
Building and to exclude from the Building all freight which violates any of the
Rules and Regulations or the provisions of such tenant's lease.

                  13.      No tenant shall use or occupy, or permit any portion
of the premises demised to such tenant to be used or occupied, as an office for
a public stenographer or typist, or to a barber or manicure shop, or as an
employment bureau. No tenant or occupant shall engage or pay any employees in
the Building, except those actually working for such tenant or occupant in the
Building, nor advertise for laborers giving an address at the Building.

                  14.      Intentionally Omitted.

                  15.      Intentionally Omitted.

                  16.      Landlord reserves the right to exclude from the
Building, between the hours of 6:00 P.M. and 8:00 A.M. on business days and at
all hours on Saturdays, Sundays and holidays, all persons who do not present a
pass to the Building signed by Landlord or are vouched for by a person with such
pass. Landlord will furnish passes to persons for whom any tenant requests such
passes. Each tenant shall be responsible for all persons for whom it requests
such passes and shall be liable to Landlord for all acts of such persons.

                  17.      Each tenant, before closing and leaving the premises
demised to such tenant at any time, shall see that all entrance doors are locked
and all windows closed. Corridor doors, when not in use, shall be kept closed.

                  18.      Each tenant shall, at its expense, provide artificial
light in the premises demised to such tenant for Landlord's agents, contractors
and employees while performing janitorial or other cleaning services and making
repairs or alterations in said premises.

                  19.      No premises shall be used, or permitted to be used
for lodging or sleeping, or for any immoral or illegal purposes.

                  20.      The requirements of tenants will be attended to only
upon application at the office of Landlord. Building employees shall not be
required to perform, and shall not be requested by any tenant or occupant to
perform, and work outside of their regular duties, unless under specific
instructions from the office of Landlord.

                  21.      Canvassing, soliciting and peddling in the Building
are prohibited and each tenant and occupant shall cooperate in seeking their
prevention.

                  22.      There shall not be used in the Building, either by
any tenant or occupant or by their agents or contractors, in the delivery or
receipt of merchandise, freight, or other matter, any hand trucks or other means
of conveyance except those equipped with rubber tires, rubber side guards and
such other safeguards as Landlord may require.

                                     - 71 -
<PAGE>

                  23.      If the Premises demised to any tenant become infested
with vermin, such tenant, at its sole cost and expense, shall cause its premises
to be exterminated, from time to time, to the satisfaction of Landlord, and
shall employ such exterminators therefor as shall be approved by Landlord.

                  24.      No premises shall be used, or permitted to be used,
at any time, without the prior approval of Landlord, as a store for the sale or
display of goods, wares or merchandise of any kind, or as a restaurant, shop,
booth, bootblack or other stand, or for the conduct of any business or
occupation which predominantly involves direct patronage of the general public
in the premises demised to such tenant, or for manufacturing or for other
similar purposes.

                  25.      No tenant shall clean any window in the Building from
the outside.

                  26.      No tenant shall place, or permit to be placed, on any
part of the floor or floors of the premises demised to such tenant, a load
exceeding the floor load per square foot which such floor was designed to carry
and which is allowed by law. Landlord reserves the right to prescribe the weight
and position of safes and other heavy matter, which must be placed so as to
distribute the weight.

                  27.      Landlord shall provide and maintain an alphabetical
directory board in the first floor (main lobby) of the Building and no other
directory shall be permitted without the prior consent of Landlord. Each tenant
shall be allowed one line on such board unless otherwise agreed to in writing.

                  28.      With respect to work being performed by a tenant in
its premises with the approval of Landlord, the tenant shall refer all
contractors, contractors' representatives and installation technicians to
Landlord for its supervision, approval and control prior to the performance of
any work or services. This provision shall apply to all work performed in the
Building including installation of telephones, telegraph equipment, electrical
devices and attachments, and installations of every nature affecting floors,
walls, woodwork, trim, ceilings, equipment and any other physical portion of the
Building.

                  29.      Landlord, absent negligence or willful act, shall not
be responsible for lost or stolen personal property, equipment, money, or
jewelry from the premises of tenants or public rooms whether or not such loss
occurs when the Building or the premises are locked against entry.

                  30.      Landlord shall not permit entrance to the premises of
tenants by use of pass keys controlled by Landlord, to any person at any time
without written permission from such tenant, except employees, contractors, or
service personnel directly supervised by Landlord.

                  31.      Each tenant and all of tenant's employees and
invitees shall observe and comply with the driving and parking signs and markers
on the Land surrounding the Building, and Landlord shall not be responsible for
any damage to any vehicle towed because of noncompliance with parking
regulations.

                  32.      Without Landlord's prior approval, no tenant shall
install any radio or television antenna, loudspeaker, music system or other
device on the roof or exterior walls of the Building.

                  33.      Each tenant shall store all trash and garbage within
its premises or in such other areas specifically designated by Landlord. No
materials shall be placed in the trash boxes or

                                     - 72 -
<PAGE>

receptacles in the Building unless such materials may be disposed of in the
ordinary and customary manner of removing and disposing of trash and garbage and
will not result in a violation of any law or ordinance governing such disposal.
All garbage and refuse disposal shall be only through entry ways and elevators
provided for such purposes and at such times as Landlord shall designate.

                  34.      Tenant shall not permit smoking of any type of
tobacco product (e.g., cigarettes, cigars, pipes, etc.) in or about the Premises
or Building by any of its employees, servants, agents, representatives,
visitors, customers, licensees, invitees, guests, contractors, or any person
whomsoever, and, upon Landlord's request, shall post in a conspicuous place or
places in or about the Premises, "No Smoking" signs or placards. Tenant
acknowledges that the Premises and Building are non-smoking facilities.

                                     - 73 -
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                                    EXHIBIT E

                       Rent Commencement Date Confirmation

                DECLARATION BY LANDLORD AND TENANT AS TO DATE OF
                DELIVERY AND ACCEPTANCE OF POSSESSION OF PREMISES

                  Attached to and made a part of the Lease dated the _____ day
of __________________ as LANDLORD, and _________________________________________
______________________________ as TENANT.

LANDLORD AND TENANT do hereby declare that possession of the Premises was
accepted by TENANT on the ____ day of _________________, 200_ (the "Effective
Date"). The Premises required to be constructed and finished by LANDLORD in
accordance with the provisions of the Lease have been satisfactorily completed
by LANDLORD and accepted by TENANT, the Lease is now in full force and effect,
and as of the date hereof, LANDLORD has fulfilled all of its obligations under
the Lease to be performed as of this date. The Rent Commencement Date is hereby
established as ______________________________, 200_. The Term of this Lease
shall terminate on ____________________, 200_, subject to extension as set forth
in the Lease.

LANDLORD:

THREE HUNDRED THIRD STREET LLC

By: MASSACHUSETTS MUTUAL LIFE
INSURANCE COMPANY

By:  CORNERSTONE REAL ESTATE
     ADVISERS, INC.,
     its authorized agent

By: ________________________________

    ________________________________
       [Printed Name and Title]

                                     - 74 -
<PAGE>

TENANT:

By: ________________________________

    ________________________________
       [Printed Name and Title]

By: ________________________________

    ________________________________
       [Printed Name and Title]

                                     - 75 -
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                                    EXHIBIT F

                                     Signage

                                     - 76 -