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                                                                    Exhibit 10.8



                               91 HARTWELL AVENUE
                            LEXINGTON, MASSACHUSETTS

                          Lease Dated January 13, 2005

         THIS INSTRUMENT IS AN INDENTURE OF LEASE in which the Landlord and the
Tenant are the parties hereinafter named, and which relates to space in a
certain building (the "Building") known as, and with an address at, 91 Hartwell
Avenue, Lexington, Massachusetts.

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

                                    ARTICLE I
                                    ---------

                                 REFERENCE DATA
                                 --------------

1.1      SUBJECTS REFERRED TO.
         ---------------------

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

<Table>
<S>                                                       <C>
         Landlord:                                        Mortimer B. Zuckerman and Edward H. Linde, Trustees
                                                          of 91 Hartwell Avenue Trust under Declaration of
                                                          Trust dated September 28, 1981 filed with the
                                                          Middlesex South Registry as Document No. 616455 as
                                                          amended by instruments dated December 10, 1984 and
                                                          April 17, 1991 respectively filed with said Registry
                                                          District as Document Nos. 675674 and 844541 but not
                                                          individually.

         Landlord's Original Address:                     c/o Boston Properties Limited Partnership
                                                          111 Huntington Avenue, Suite 300
                                                          Boston, Massachusetts 02199-7610

         Landlord's Construction Representative:          Michael Schumacher

         Tenant:                                          Synta Pharmaceuticals, Inc., a Delaware corporation.

         Tenant's Original Address:                       45 Hartwell Avenue
                                                          Lexington, Massachusetts 02421


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         Tenant's Construction Representative:
                                                          ------------------------------------

         Commencement Date:                               January 15, 2005

         Second Floor Premises Rent                       February 15, 2005
         Commencement Date:

         Third Floor Premises Rent                        July 1, 2005
         Commencement Date:

         Original Term:                                   Twenty-five (25) calendar months (plus
                                                          the partial month, if any, immediately
                                                          following the Commencement Date),
                                                          unless extended or sooner terminated as
                                                          provided in this Lease.

         Extension Option:                                One (1) period of one (1) year as provided in and on
                                                          the terms set forth in Section 2.4.1 hereof.

         Term or Lease Term:                              All references in this Lease or to the Term
                                                          or Lease Term shall mean the Original Term
                                                          and if extended pursuant to Section 2.4.1, the Original
                                                          Term as extended by the exercise of the extension option
                                                          unless otherwise specifically provided in this Lease.

         The Site:                                        That certain parcel of land known as and numbered 91
                                                          Hartwell Avenue, Lexington, Middlesex Count, Massachusetts,
                                                          being more particularly described in Exhibit A attached
                                                          hereto. The Building (as defined below) is the only structure
                                                          located on the Site.

         The Building:                                    The Building known as and numbered 91 Hartwell
                                                          Avenue, Lexington, Massachusetts.

         The Complex:                                     The Building together with all surface parking areas,
                                                          the Site and all improvements (including landscaping)
                                                          thereon and thereto.

         Tenant's Space:                                  A portion of the second (2nd) floor of the Building
                                                          (the "Second Floor Premises") and a portion of the
                                                          third (3rd) floor of the Building (the "Third Floor
                                                          Premises"), in


                                      -2-


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                                                          accordance with the floor plan annexed
                                                          hereto as Exhibit D and incorporated herein by
                                                          reference.

         Number of Parking Spaces:                        Seventy-six (76) spaces.

         Annual Fixed Rent:                               (a)  With respect to the Second Floor Premises, for
                                                          the period commencing on the Second Floor Premises
                                                          Rent Commencement Date and ending on the last day of
                                                          the Original Term of this Lease at the annual rate of
                                                          $268,398.00, being the product of (i) $19.50 and (ii)
                                                          the "Rentable Floor Area of the Second Floor
                                                          Premises" (hereinafter defined in this Section 1.1).

                                                          (b) With respect to the Third Floor Premises, for the
                                                          period commencing on the Third Floor Premises Rent
                                                          Commencement Date and ending on the last day
                                                          of the Original Term of this Lease at the annual rate of
                                                          $157,326.00, being the product of (i) $19.50
                                                          and (ii) the "Rentable Floor Area of the Third Floor
                                                          Premises" (hereinafter defined in this Section 1.1).

                                                          (c)  During the extension option period (if
                                                          exercised), as determined pursuant to Section 2.4.1).

         Operating Expenses:                              As provided in Section 2.6 hereof.

         Real Estate Taxes:                               As provided in Section 2.7 hereof.

         Tenant Electricity:                              Initially as provided in Section 2.5 subject to
                                                          adjustment as provided in Section 2.8 hereof.

         Additional Rent:                                 All charges and other sums payable by Tenant as set
                                                          forth in this Lease, in addition to Annual Fixed Rent.

         Rentable Floor Area of Tenant's Space            21,832 rentable square feet, consisting of 13,764
         (sometimes also called "Rentable Floor           square feet of rentable floor area in the Second
         Area of the Premises"):                          Floor Premises (the "Rentable Floor Area of the
                                                          Second Floor Premises") and 8,068 square feet of
                                                          rentable floor area in the Third Floor Premises (the
                                                          "Rentable Floor Area of the Third Floor Premises").


                                      -3-


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         Total Rentable Floor Area of the Building:       122,328 rentable square feet.

         Permitted Use:                                   General office purposes.

         Initial Minimum Limits of Tenant's               $5,000,000.00 combined single limit per occurrence on
         Commercial General Liability Insurance:          a per location basis.

         Broker:                                          Richards Barry Joyce & Partners
                                                          53 State Street, 29th Floor
                                                          Boston, Massachusetts 02110

         Security Deposit:                                $35,477.00
</Table>


1.2      EXHIBITS.
         ---------

         There are incorporated as part of this Lease:

         Exhibit A         --       Description of Site

         Exhibit B         --       Intentionally Omitted

         Exhibit C         --       Landlord's Services

         Exhibit D         --       Floor Plan

         Exhibit E         --       Intentionally Omitted

         Exhibit F         --       Form of Lien Waivers


1.3      TABLE OF ARTICLES AND SECTIONS.
         -------------------------------

<Table>
<S>                                                                                                    <C>     <C>
         ARTICLE I.......................................................................................1
                  REFERENCE DATA..................................................................................1
                           1.1      SUBJECTS REFERRED TO..........................................................1
                           1.2      EXHIBITS......................................................................4
                           1.3      TABLE OF ARTICLES AND SECTIONS................................................4

         ARTICLE II......................................................................................6
                  BUILDING, PREMISES, TERM AND RENT...............................................................6
                           2.1      THE PREMISES..................................................................6


                                      -4-

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                           2.2      RIGHTS TO USE COMMON FACILITIES...............................................6
                           2.3      LANDLORD'S RESERVATIONS.......................................................7
                           2.4      HABENDUM......................................................................8
                           2.5      FIXED RENT PAYMENTS...........................................................8
                           2.6      OPERATING EXPENSES............................................................9
                           2.7      REAL ESTATE TAXES............................................................11
                           2.8      TENANT ELECTRICITY...........................................................14

         ARTICLE III....................................................................................15
                  CONDITION OF PREMISES; ALTERATIONS.............................................................15
                           3.1      CONDITION OF PREMISES........................................................15
                           3.2      QUALITY AND PERFORMANCE OF WORK..............................................15
                           3.3      SPECIAL ALLOWANCE............................................................15

         ARTICLE IV.....................................................................................16
                  LANDLORD'S COVENANTS; INTERRUPTIONS AND DELAYS.................................................16
                           4.1      LANDLORD COVENANTS:..........................................................16
                           4.2      INTERRUPTIONS AND DELAYS IN SERVICES AND REPAIRS, ETC........................17

         ARTICLE V......................................................................................18
                  TENANT'S COVENANTS.............................................................................18
                           5.1      PAYMENTS.....................................................................18
                           5.2      REPAIR AND YIELD UP..........................................................18
                           5.3      USE..........................................................................18
                           5.4      OBSTRUCTIONS; ITEMS VISIBLE FROM EXTERIOR; RULES AND REGULATIONS.............19
                           5.5      SAFETY APPLIANCES............................................................19
                           5.6      ASSIGNMENT; SUBLEASE.........................................................19
                           5.7      INDEMNITY; INSURANCE.........................................................25
                           5.8      PERSONAL PROPERTY AT TENANT'S RISK...........................................26
                           5.9      RIGHT OF ENTRY...............................................................26
                           5.10     FLOOR LOAD; PREVENTION OF VIBRATION AND NOISE................................27
                           5.11     PERSONAL PROPERTY TAXES......................................................27
                           5.12     COMPLIANCE WITH LAWS.........................................................27
                           5.13     PAYMENT OF LITIGATION EXPENSES...............................................27
                           5.14     ALTERATIONS..................................................................28
                           5.15     VENDORS......................................................................29

         ARTICLE VI.....................................................................................30
                  CASUALTY AND TAKING............................................................................30
                           6.1      DAMAGE RESULTING FROM CASUALTY...............................................30
                           6.2      UNINSURED CASUALTY...........................................................31
                           6.3      RIGHTS OF TERMINATION FOR TAKING.............................................31
                           6.4      AWARD........................................................................32


                                      -5-


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         ARTICLE VII....................................................................................32
                  DEFAULT  32
                           7.1      TENANT'S DEFAULT.............................................................32
                           7.2      LANDLORD'S DEFAULT...........................................................36

         ARTICLE VIII...................................................................................37
                  MISCELLANEOUS PROVISIONS.......................................................................37
                           8.1      EXTRA HAZARDOUS USE..........................................................37
                           8.2      WAIVER.......................................................................37
                           8.3      CUMULATIVE REMEDIES..........................................................37
                           8.4      QUIET ENJOYMENT..............................................................38
                           8.5      NOTICE TO MORTGAGEE AND GROUND LESSOR........................................39
                           8.6      ASSIGNMENT OF RENTS..........................................................39
                           8.7      SURRENDER....................................................................40
                           8.8      BROKERAGE....................................................................40
                           8.9      INVALIDITY OF PARTICULAR PROVISIONS..........................................40
                           8.10     PROVISIONS BINDING, ETC......................................................40
                           8.11     RECORDING....................................................................41
                           8.12     NOTICES......................................................................41
                           8.13     WHEN LEASE BECOMES BINDING...................................................42
                           8.14     SECTION HEADINGS.............................................................42
                           8.15     RIGHTS OF MORTGAGEE..........................................................42
                           8.16     STATUS REPORTS AND FINANCIAL STATEMENTS......................................43
                           8.17     SELF-HELP....................................................................43
                           8.18     HOLDING OVER.................................................................44
                           8.19     NON-SUBROGATION..............................................................44
                           8.20     SECURITY DEPOSIT.............................................................44
                           8.21     LATE PAYMENT.................................................................45
                           8.22     TENANT'S PAYMENTS............................................................45
                           8.23     WAIVER OF TRIAL BY JURY......................................................46
                           8.24     GOVERNING LAW................................................................46
</Table>

                                   ARTICLE II
                                   ----------

                        BUILDING, PREMISES, TERM AND RENT
                        ---------------------------------

2.1      THE PREMISES.

         Landlord hereby demises and leases to Tenant, and Tenant hereby hires
         and accepts from Landlord, Tenant's Space in the Building excluding
         exterior faces of exterior walls, the common stairways and stairwells,
         elevators and elevator wells, fan rooms, electric and telephone
         closets, janitor closets, and pipes, ducts, conduits, wires and
         appurtenant fixtures serving exclusively, or in common, other parts of
         the Building, and if Tenant's Space includes less than the entire
         rentable area of any floor, excluding the common corridors, elevator
         lobbies and toilets located on such floor.


                                      -6-


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         Tenant's Space with such exclusions is hereinafter referred to as the
         "Premises." The term "Building" means the Building identified on the
         first page, and which is the subject of this Lease; the term "Site"
         means all, and also any part of the Land described in Exhibit A, plus
         any additions or reductions thereto resulting from the change of any
         abutting street line and all parking areas and structures. The term
         "Property" means the Building and the Site.

2.2      RIGHTS TO USE COMMON FACILITIES.
         -------------------------------

         Subject to Landlord's right to change or alter any of the following in
         Landlord's discretion as herein provided, Tenant shall have, as
         appurtenant to the Premises, the non-exclusive right to use in common
         with others, subject to reasonable rules of general applicability to
         tenants of the Building from time to time made by Landlord of which
         Tenant is given notice (a) the common lobbies, corridors, stairways,
         elevators and loading area of the Building, and the pipes, ducts,
         conduits, wires and appurtenant meters and equipment serving the
         Premises in common with others, (b) common walkways and driveways
         necessary for access to the Building, and (c) if the Premises include
         less than the entire rentable floor area of any floor, the common
         toilets, corridors and elevator lobby of such floor. Notwithstanding
         anything to the contrary herein, Landlord has no obligation to allow
         any particular telecommunication service provider to have access to the
         Building or to the Premises except as may be required by applicable
         law. If Landlord permits such access, Landlord may condition such
         access upon the payment to Landlord by the service provider of fees
         assessed by Landlord in its sole discretion.

         2.2.1    TENANT'S PARKING.
                  ----------------

                  In addition, Tenant shall have the right to use the Number of
                  Parking Spaces (referred to in Section 1.1) of the parking
                  area, in common with use by other tenants from time to time of
                  the Complex; provided, however, Landlord shall not be
                  obligated to furnish stalls or spaces in any parking area
                  specifically designated for Tenant's use. Tenant covenants and
                  agrees that it and all persons claiming by, through and under
                  it, shall at all times abide by all reasonable rules and
                  regulations promulgated by Landlord with respect to the use of
                  the parking areas on the Site. The parking privileges granted
                  herein are non-transferable except to a permitted assignee or
                  subtenant as provided in Section 5.6 through Section 5.6.6.
                  Further, Landlord assumes no responsibility whatsoever for
                  loss or damage due to fire, theft or otherwise to any
                  automobile(s) parked on the Site or to any personal property
                  therein, however caused, and Tenant covenants and agrees, upon
                  request from Landlord from time to time, to notify its
                  officers, employees, agents and invitees of such limitation of
                  liability. Tenant acknowledges and agrees that a license only
                  is hereby granted, and no bailment is intended or shall be
                  created.

2.3      LANDLORD'S RESERVATIONS.
         -----------------------

         Landlord reserves the right from time to time, without unreasonable
         interference with Tenant's use: (a) to install, use, maintain, repair,
         replace and relocate for service to the Premises and other parts of the
         Building, or either, pipes, ducts, conduits, wires and


                                      -7-


<Page>


         appurtenant fixtures, wherever located in the Premises or Building,
         and (b) to alter or relocate any other common facility, provided that
         substitutions are substantially equivalent or better. Installations,
         replacements and relocations referred to in clause (a) above shall be
         located so far as practicable in the central core area of the
         Building, above ceiling surfaces, below floor surfaces or within
         perimeter walls of the Premises. Except in the event of an emergency,
         Landlord shall provide Tenant with forty-eight (48) hours advance
         notice of the above-referenced work if such work shall adversely
         affect Tenant's use of or access to the Premises, the common areas of
         the Site and/or the parking area.

2.4      HABENDUM.
         --------

         Tenant shall have and hold the Premises for a period commencing on the
         Commencement Date, and continuing for the Term unless sooner terminated
         as provided in Article VI or Article VII or unless extended as provided
         in Section 2.4.1.

         2.4.1    EXTENSION OPTION.
                  ----------------

                  (A) On the conditions (which conditions Landlord may waive by
                  written notice to Tenant) that both at the time of exercise of
                  the option to extend and at the commencement date of the
                  extension option period (i) there exists no Event of Default
                  (defined in Section 7.1), (ii) this Lease is still in full
                  force and effect, and (iii) Tenant has not assigned this
                  (except for an assignment permitted without Landlord's consent
                  under Section 5.6.1 hereof), Tenant shall have the right to
                  extend the Term hereof upon all the same Annual Fixed Rent,
                  terms, conditions, covenants and agreements herein contained
                  (except that the only extension option shall be as set forth
                  in this Section 2.4.1) for one (1) period of one (1) year as
                  hereinafter set forth. Such option period is sometimes herein
                  referred to as an "Extended Term." Notwithstanding any
                  implication to the contrary Landlord has no obligation to make
                  any additional payment to Tenant in respect of any
                  construction allowance or the like or to perform any work to
                  the Premises as a result of the exercise by Tenant of such
                  option.

                  (B) If Tenant desires to exercise the option to extend the
                  Term, then Tenant shall give notice to Landlord, not earlier
                  than twelve (12) months nor later than six (6) months prior to
                  the expiration of the Original Term. Upon the giving of such
                  notice, this Lease and the Term hereof shall be extended for
                  the option period, without the necessity for the execution of
                  any additional documents (except that Landlord and Tenant
                  agree to enter into an instrument in writing setting forth the
                  fixed rent); and in such event all references herein to the
                  Term or the term of this Lease shall be construed as referring
                  to the Term, as so extended, unless the context clearly
                  otherwise requires.

2.5      FIXED RENT PAYMENTS.
         -------------------

         Tenant agrees to pay to Landlord, or as directed by Landlord, at
         Landlord's Original Address specified in Section 1.1 hereof, or at such
         other place as Landlord shall from time to time designate by notice,
         (1)(a) on the Second Floor Premises Rent


                                      -8-


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         Commencement Date with respect to the Second Floor Premises and on the
         Third Floor Premises Rent Commencement Date with respect to the Third
         Floor Premises, respectively, and thereafter monthly, in advance, on
         the first day of each and every calendar month during the Original
         Term, a sum equal to one twelfth (1/12th) of the applicable Annual
         Fixed Rent (sometimes hereinafter referred to as "fixed rent") and (b)
         on the Commencement Date and thereafter monthly, in advance, on the
         first day of each and every calendar month during the Original Term, a
         sum equal to one twelfth (1/12th) of $1.00 per annum for each square
         foot of Rentable Floor Area of Tenant's Space for tenant electricity
         subject to escalation as provided in Section 2.8 and (2) on the first
         day of each and every calendar month during the extension option
         period (if exercised), a sum equal to (a) one twelfth (1/12th) of the
         Annual Fixed Rent as determined in Section 2.4.1 for the extension
         option period plus (b) then applicable monthly electricity charges
         (subject to escalation for electricity as provided in Section 2.8
         hereof). Until notice of some other designation is given, fixed rent
         and all other charges for which provision is herein made shall be paid
         by remittance to or for the order of Boston Properties Limited
         Partnership, Agents at P.O. Box 3557, Boston, Massachusetts
         02241-3557, and all remittances received by Boston Properties Limited
         Partnership, as Agents as aforesaid, or by any subsequently designated
         recipient, shall be treated as payment to Landlord.

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

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

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

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


                                      -9-


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2.6      OPERATING EXPENSES.
         ------------------

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

         "Tenant's Share" shall mean 17.85%.

         "Operating Expenses Allocable to the Premises" shall mean Tenant's
         Share of Landlord's Operating Expenses for and pertaining to the
         Building and the Site.

         "Base Operating Expenses" shall mean Landlord's Operating Expenses for
         calendar year 2005 (that is, the period beginning January 1, 2005 and
         ending December 31, 2005). Base Operating Expenses shall not include
         market-wide cost increases due to extraordinary circumstances, included
         but not limited to Force Majeure (as defined in Section 6.1),
         conservation surcharges, boycotts, strikes, embargoes or shortages.


                                      -10-


<Page>


         "Base Operating Expenses Allocable to the Premises" shall mean Tenant's
         Share of Base Operating Expenses.

         If with respect to any calendar year falling within the Term, or
         fraction of a calendar year falling within the Term at the beginning or
         end thereof, the Operating Expenses Allocable to the Premises for a
         full calendar year exceed Base Operating Expenses Allocable to the
         Premises or for any such fraction of a calendar year exceed the
         corresponding fraction of Base Operating Expenses Allocable to the
         Premises (such amount being hereinafter sometimes referred to as the
         "Operating Cost Excess") then, Tenant shall pay to Landlord, as
         Additional Rent, the amount of such excess. Such payments shall be made
         at the times and in the manner hereinafter provided in this Section
         2.6. (The Base Operating Expenses Allocable to the Premises do not
         include the $1.00 for tenant electricity to be paid by Tenant together
         with Annual Fixed Rent and for which provision is made in Section 2.5
         hereof, separate provision being made in Section 2.8 of this Lease for
         Tenant's share of increases in electricity costs.)

         Not later than one hundred and twenty (120) days after the end of the
         first calendar year or fraction thereof ending December 31 and of each
         succeeding calendar year during the Term or fraction thereof at the end
         of the Term, Landlord shall render Tenant a statement in reasonable
         detail and according to generally accepted accounting practices
         certified by a representative of Landlord, showing for the preceding
         calendar year or fraction thereof, as the case may be, Base Operating
         Expenses, Landlord's Operating Expenses and Operating Expenses
         Allocable to the Premises. Said statement to be rendered to Tenant
         shall also show for the preceding year or fraction thereof as the case
         may be the amounts of operating expenses already paid by Tenant as
         Additional Rent on account of the operating expenses and the amount of
         the Operating Cost Excess remaining due from, or overpaid by, Tenant
         for the year or other period covered by the statement. Within thirty
         (30) days after the date of delivery of such statement, Tenant shall
         pay to Landlord the balance of the amounts, if any, required to be paid
         pursuant to the above provisions of this Section 2.6 with respect to
         the preceding year or fraction thereof, or Landlord shall credit any
         amounts overpaid by Tenant against (i) monthly installments of fixed
         rent next thereafter coming due or (ii) any sums then due from Tenant
         to Landlord under this Lease (or refund such portion of the overpayment
         as aforesaid if the Term has ended and Tenant has no further obligation
         to Landlord).

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

         Notwithstanding the foregoing provisions, no decrease in Landlord's
         Operating Expenses shall result in a reduction of the amount otherwise
         payable by Tenant if and to the extent said decrease is attributable to
         vacancies in the Building rather than to any other causes.


                                      -11-


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2.7      REAL ESTATE TAXES.
         -----------------

         If with respect to any full Tax Year or fraction of a Tax Year falling
         within the Term, Landlord's Tax Expenses Allocable to the Premises (as
         hereinafter defined) for a full Tax Year exceed Base Taxes Allocable to
         the Premises or for any such fraction of a Tax Year exceed the
         corresponding fraction of Base Taxes Allocable to the Premises (such
         amount being hereinafter sometimes referred to as the "Tax Excess")
         then, on or before the thirtieth (30th) day following receipt by Tenant
         of the certified statement referred to below in this Section 2.7, then
         Tenant shall pay to Landlord, as Additional Rent, the amount of the Tax
         Excess. Not later than ninety (90) days after Landlord's Tax Expenses
         Allocable to the Premises are determined for the first such Tax Year or
         fraction thereof and for each succeeding Tax Year or fraction thereof
         during the Term, Landlord shall render Tenant a statement in reasonable
         detail certified by a representative of Landlord showing for the
         preceding year or fraction thereof, as the case may be, real estate
         taxes on the Building and the Site and abatements and refunds of any
         taxes and assessments. Expenditures for legal fees and for other
         expenses incurred in seeking the tax refund or abatement may be charged
         against the tax refund or abatement before the adjustments are made for
         the Tax Year. Said statement to be rendered to Tenant shall also show
         for the preceding Tax Year or fraction thereof as the case may be the
         amounts of real estate taxes already paid by Tenant as Additional Rent,
         and the amount of real estate taxes remaining due from, or overpaid by,
         Tenant for the year or other period covered by the statement. Within
         thirty (30) days after the date of delivery of the foregoing statement,
         Tenant shall pay to Landlord the balance of the amounts, if any,
         required to be paid pursuant to the above provisions of this Section
         2.7 with respect to the preceding Tax Year or fraction thereof, or
         Landlord shall credit any amounts due from it to Tenant pursuant to the
         provisions of this Section 2.7 against (i) monthly installments of
         fixed rent next thereafter coming due or (ii) any sums then due from
         Tenant to Landlord under this Lease (or refund such portion of the
         over-payment as aforesaid if the Term has ended and Tenant has no
         further obligation to Landlord).

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

         To the extent that real estate taxes shall be payable to the taxing
         authority in installments with respect to periods less than a Tax Year,
         the foregoing statement shall be rendered and payments made on account
         of such installments. Notwithstanding the foregoing provisions, no
         decrease in Landlord's Tax Expenses with respect to any Tax Year shall
         result in a reduction of the amount otherwise payable by Tenant if and
         to the extent said decrease is attributable to vacancies in the
         Building or partial completion of the Building rather than to any other
         causes.


                                      -12-


<Page>


         Terms used herein are defined as follows:

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

         (ii)  "Tenant's Tax Share" means 18.79%.

         (iii) "Landlord's Tax Expenses Allocable to the Premises" shall mean
               Tenant's Tax Share of Landlord's Tax Expenses.

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

         (v)   "Base Taxes" means Landlord's Tax Expenses (hereinbefore defined)
               for fiscal tax year 2006 (that is, the period beginning July 1,
               2005 and ending June 30, 2006).

         (vi)  "Base Taxes Allocable to the Premises" means Tenant's Tax Share
               of Base Taxes.

         (vii) "Real estate taxes" means all taxes and special assessments of
               every kind and nature and user fees and other like fees assessed
               by any governmental authority on the Building or Site which the
               Landlord shall become obligated to pay because of or in
               connection with the ownership, leasing or operation of the Site,
               the Building and the Property (including, without limitation, if
               applicable the excise prescribed by Mass Gen Laws Chapter 121A,
               Section 10 and amounts in excess thereof paid to the Town of
               Lexington pursuant to agreement between Landlord and the Town)
               and reasonable expenses of and fees for any formal or informal
               proceedings for negotiation or abatement of taxes (collectively,
               "Abatement Expenses"), which Abatement Expenses shall be excluded
               from Base Taxes. The amount of special taxes or special
               assessments to be included shall be limited to the amount of the
               installment (plus any interest, other than penalty interest,
               payable thereon) of such special tax or special assessment
               required to be paid during the year in respect of which such
               taxes are being determined. There shall be excluded from such
               taxes all late fees or penalties, and income, estate, succession,
               inheritance and transfer taxes; provided, however, that if at any
               time during the Term the present system of ad valorem taxation of
               real property shall be changed so that in lieu of, or in addition
               to, the whole or any part of the ad valorem tax on real property
               there shall be assessed on Landlord a capital levy or other tax
               on the gross rents received with respect to the Site or Building
               or Property, or a federal, state, county, municipal, or other
               local income, franchise, excise or similar tax, assessment, levy
               or charge (distinct from any now in effect in the jurisdiction in
               which the Property is located) measured by or based, in whole or
               in part, upon any such gross rents, then any and all of such
               taxes, assessments, levies or charges, to the extent so measured
               or based, shall be


                                      -13-


<Page>


               deemed to be included within the term "real estate taxes" but
               only to the extent that the same would be payable if the Site and
               Building were the only property of Landlord.

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

2.8      TENANT ELECTRICITY.
         ------------------

         The current cost of furnishing electricity to the base building
         components of the Building and the Site is approximately $1.36 per
         square foot of the Total Rentable Floor Area of the Building and the
         current cost of furnishing electricity to the tenant spaces in the
         Building is approximately $1.15 per square foot of the Total Rentable
         Floor Area of the Building. The costs of electricity consumption
         chargeable to the tenants of the Building are based on the costs
         charged to Landlord by the local utility company providing service to
         the Building and the Site and are passed through to the tenants without
         mark-up. If with respect to any calendar year falling within the Term
         or fraction of a calendar year falling within the Term at the beginning
         or end thereof, the cost of furnishing electricity to the Building and
         the Site, including common areas and facilities and space occupied by
         tenants, (but expressly excluding utility charges separately chargeable
         to tenants for additional or special services) for a full calendar year
         exceeds $1.00 per square foot of Rentable Floor Area of the Building,
         or for any such fraction of a calendar year exceeds the corresponding
         fraction of $1.00 per square foot of Rentable Floor Area of the
         Building, then Tenant shall pay to Landlord, as Additional Rent, on or
         before the thirtieth (30th) day following receipt by Tenant of the
         statement referred to below in this Section 2.8, its proportionate
         share of the amount of such excess (i.e. the same proportion of such
         excess as the Rentable Floor Area of Tenant's Space bears to the Total
         Rentable Floor Area of the Building). In no event shall Tenant be
         responsible for any increases in the cost of electricity caused by
         another tenant's excessive use. Payments by Tenant on account of such
         excess shall be made monthly at the time and in the fashion herein
         provided for the payment of Annual Fixed Rent. The amount so to be paid
         to Landlord shall be an amount from time to time reasonably estimated
         by Landlord to be sufficient to cover, in the aggregate, a sum equal to
         such excess for each calendar year during the Term. If the Landlord
         shall reasonably determine that the cost of electricity furnished to
         the Tenant at the Premises exceeds the amount being paid under Sections
         2.5 and 2.8, then the Landlord may charge the Tenant for such excess
         and the Tenant shall promptly pay the same upon billing therefor.

         Not later than ninety (90) days after the end of the first calendar
         year or fraction thereof ending December 31 and of each succeeding
         calendar year during the Term or fraction thereof at the end of the
         Term, Landlord shall render Tenant a reasonably detailed accounting
         certified by a representative of Landlord showing for the preceding
         calendar year, or fraction thereof, as the case may be, the costs of
         furnishing electricity to the Building. Said statement to be rendered
         to Tenant also shall show for the preceding year or fraction thereof,
         as the case may be, the amount already paid by Tenant on account of
         electricity, and the amount remaining due from, or overpaid by, Tenant
         for the year or


                                      -14-


<Page>


         other period covered by the statement. Within thirty (30) days after
         the date of the delivery of such statement, Tenant shall pay to
         Landlord the balance of the amounts, if any required to be paid
         pursuant to the above provisions of this Section 2.8 with respect to
         the preceding year, or fraction thereof, or Landlord shall credit any
         amounts due from it to Tenant pursuant to the above provisions of this
         Section 2.8 against monthly installments of Annual Fixed Rent or
         Additional Rent next thereafter coming due unless the Lease Term has
         expired and Tenant has no other or further obligations to Landlord, in
         which case Landlord shall promptly refund such amount to Tenant.

                                   ARTICLE III
                                   -----------

                       CONDITION OF PREMISES; ALTERATIONS
                       ----------------------------------

3.1      CONDITION OF PREMISES.
         ---------------------

         Tenant shall accept the Premises in their As-Is condition without any
         obligation on the Landlord's part to perform any additions,
         alterations, improvements, demolition or other work therein or
         pertaining thereto.

3.2      QUALITY AND PERFORMANCE OF WORK.
         -------------------------------

         All construction work required or permitted by this Lease shall be done
         in a good and workmanlike manner and in compliance with all applicable
         laws, ordinances, rules, regulations, statutes, by-laws, court
         decisions, and orders and requirements of all public authorities
         ("Legal Requirements") and all Insurance Requirements (as defined in
         Section 5.14 hereof). All of Tenant's work shall be coordinated with
         any work being performed by or for Landlord and in such manner as to
         maintain harmonious labor relations. Each party may inspect the work of
         the other at reasonable times and shall promptly give notice of
         observed defects. Each party authorizes the other to rely in connection
         with design and construction upon approval and other actions on the
         party's behalf by any Construction Representative of the party named in
         Section 1.1 or any person hereafter designated in substitution or
         addition by notice to the party relying. Except to the extent to which
         Tenant shall have given Landlord notice of respects in which Landlord
         has not performed Landlord's construction obligations under this
         Article III (if any) (i) not later than the end of the sixth (6th) full
         calendar month next beginning after the Commencement Date with respect
         to the heating, ventilating and air conditioning systems servicing the
         Premises, and (ii) not later than the third (3rd) full calendar month
         next beginning after the Commencement Date with respect to Landlord's
         construction obligations under this Article III not referenced in (i)
         above, Tenant shall be deemed conclusively to have approved Landlord's
         construction and shall have no claim that Landlord has failed to
         perform any of Landlord's obligations under this Article III (if any).
         Landlord agrees to correct or repair at its expense items which are
         then incomplete or do not conform to the work contemplated under the
         Plans and as to which, in either case, Tenant shall have given notice
         to Landlord, as aforesaid.


                                      -15-


<Page>


3.3      SPECIAL ALLOWANCE.
         -----------------

         Landlord shall provide to Tenant a special allowance equal to the
         product of (i) $6.00 and (ii) the Rentable Floor Area of the Premises
         (the "Tenant Allowance"). The Tenant Allowance shall be used and
         applied by Tenant solely on account of the cost of work performed by or
         on behalf of Tenant ("Tenant's Work"), which such Tenant's Work shall
         be performed in accordance with the terms of this Lease. Provided that
         the Tenant (i) has opened for business in the Premises, (ii) has
         completed all of such Tenant's Work in accordance with the terms of
         this Lease, has paid for all of such Tenant's Work in full and has
         delivered to Landlord lien waivers from all persons who might have a
         lien as a result of such work, in the recordable forms attached hereto
         as Exhibit F, (iii) has delivered to Landlord its certificate
         specifying the cost of such Tenant's Work and all contractors,
         subcontractors and supplies involved with Tenant's Work, together with
         evidence of such cost in the form of paid invoices, receipts and the
         like, (iv) has satisfied the requirements of (i) through (iii) above
         and made request for such payment on or before May 1, 2006, (v) is not
         otherwise in default under this Lease, and (vi) there are no liens
         (unless bonded to the reasonable satisfaction of Landlord) against
         Tenant's interest in the Lease or against the Building or the Site
         arising out of Tenant's Work or any litigation in which Tenant is a
         party, then within thirty (30) days after the satisfaction of the
         foregoing conditions, the Landlord shall pay to the Tenant the lesser
         of the amount of such costs so certified or the amount of the Tenant
         Allowance. Notwithstanding the foregoing, Tenant shall have the option
         to request Landlord to make two separate disbursements of the Tenant
         Allowance (one prior to final completion of the Tenant's Work and one
         upon completion of the same), provided that in the case of the request
         made prior to final completion (1) Tenant has satisfied the
         requirements of items (ii) through (vi) above with respect to that
         portion of the Tenant's Work completed prior to the date of the request
         and (2) the disbursement requested by Tenant equals $21,832.00 or more.
         For the purposes hereof, the cost to be so reimbursed by Landlord shall
         include (x) the cost of leasehold improvements, engineering fees,
         architectural fees and third-party supervision or management fees and
         (y) up to $21,832.00 towards the cost of Tenant's voice and data
         cabling, personal property, trade fixtures or trade equipment, moving
         expenses or any so-called soft costs.

         Notwithstanding the foregoing, Landlord shall be under no obligation to
         apply any portion of the Tenant Allowance for any purposes other than
         as provided in this Section 3.4, nor shall Landlord be deemed to have
         assumed any obligations, in whole or in part, of Tenant to any
         contractors, subcontractors, suppliers, workers or materialmen.
         Further, in no event shall Landlord be required to make application of
         any portion of the Tenant Allowance on account of any supervisory fees,
         overhead, management fees or other payments to Tenant, or any partner
         or affiliate of Tenant. In the event that such cost of Tenant's Work is
         less than the Tenant Allowance, Tenant shall not be entitled to any
         payment or credit nor shall there be any application of the same toward
         Annual Fixed Rent or Additional Rent owed by Tenant under this Lease.


                                      -16-


<Page>


                                   ARTICLE IV
                                   ----------

                 LANDLORD'S COVENANTS; INTERRUPTIONS AND DELAYS
                 ----------------------------------------------

4.1      LANDLORD COVENANTS:
         ------------------

         4.1.1    SERVICES FURNISHED BY LANDLORD.
                  ------------------------------

                  To furnish services, utilities, facilities and supplies set
                  forth in Exhibit C equal to those customarily provided by
                  landlords in high quality buildings in the Boston West
                  Suburban Market subject to escalation reimbursement in
                  accordance with Section 2.6.

         4.1.2    ADDITIONAL SERVICES AVAILABLE TO TENANT.
                  ---------------------------------------

                  To furnish, at Tenant's expense, reasonable additional
                  Building operation services which are usual and customary in
                  similar office buildings in the Boston West Suburban Market
                  upon reasonable advance request of Tenant at reasonable and
                  equitable rates from time to time established by Landlord.
                  Tenant agrees to pay to Landlord, as Additional Rent, the
                  reasonable cost of any such additional Building services
                  requested by Tenant and for the reasonable cost of any
                  additions, alterations, improvements or other work performed
                  by Landlord in the Premises at the request of Tenant within
                  thirty (30) days after being billed therefor.

         4.1.3    ROOF, EXTERIOR WALL, FLOOR SLAB AND COMMON FACILITY REPAIRS.
                  -----------------------------------------------------------

                  Except for (a) normal and reasonable wear and use and (b)
                  damage caused by fire and casualty and by eminent domain, and
                  except as otherwise provided in Article VI and subject to the
                  escalation provisions of Section 2.6, (i) to make such repairs
                  to the structural portions of the Building (including but not
                  limited to the roof, exterior walls and floor slabs) and to
                  the common areas and facilities as may be necessary to keep
                  them in serviceable condition and (ii) to maintain the
                  Building (exclusive of Tenant's responsibilities under this
                  Lease) in a first class manner comparable to the maintenance
                  of similar properties in the Boston West Suburban Market.

         4.1.4    DOOR SIGNS.
                  ----------

                  To provide and install, at Landlord's expense, letters or
                  numerals on the exterior doors to the Premises to identify
                  Tenant's official name and Building address; all such letters
                  and numerals shall be in the building standard graphics and no
                  others shall be used or permitted on the Premises.


                                      -17-


<Page>


4.2      INTERRUPTIONS AND DELAYS IN SERVICES AND REPAIRS, ETC.
         -----------------------------------------------------

         Landlord shall not be liable to Tenant for any compensation or
         reduction of rent by reason of inconvenience or annoyance or for loss
         of business arising from the necessity of Landlord or its agents
         entering the Premises for any of the purposes in this Lease authorized,
         or for repairing the Premises or any portion of the Building however
         the necessity may occur. In case Landlord is prevented or delayed from
         making any repairs, alterations or improvements, or furnishing any
         services or performing any other covenant or duty to be performed on
         Landlord's part, by reason of any cause reasonably beyond Landlord's
         control, including without limitation the causes set forth in Section
         3.2 hereof as being reasonably beyond Landlord's control, Landlord
         shall not be liable to Tenant therefor, nor, except as expressly
         otherwise provided in Article VI, shall Tenant be entitled to any
         abatement or reduction of rent by reason thereof, or right to terminate
         this Lease, nor shall the same give rise to a claim in Tenant's favor
         that such failure constitutes actual or constructive, total or partial,
         eviction from the Premises.

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

         In the event that the electrical, heating, ventilating, air
         conditioning, or all elevator service to the Premises shall be shut
         down for more than five (5) full and consecutive business days, but
         only as a result of causes which are covered by Landlord's loss of
         rentals insurance, then, Tenant shall be entitled to an abatement of
         Annual Fixed Rent equal to the "Insurance Amount" (hereinafter
         defined). The "Insurance Amount" shall be an amount equal to the
         payment actually received by Landlord (but only allocable to and on
         account of the Premises) for such shut down of electricity service to
         the Premises from Landlord's insurance carrier providing such loss of
         rents insurance less the amount of any deductible contained in such
         loss of rents insurance coverage. Notwithstanding anything herein
         contained to the contrary, in no event shall any of the events referred
         to in this Section give rise to a claim in Tenant's favor that such
         failure constitutes actual or constructive, total or partial, eviction
         from the Premises.


                                      -18-


<Page>


                                    ARTICLE V
                                    ---------

                               TENANT'S COVENANTS
                               ------------------

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

5.1      PAYMENTS.
         --------

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

5.2      REPAIR AND YIELD UP.
         -------------------

         Except as otherwise provided in Article VI and Section 4.1.3, to keep
         the Premises in good order, repair and condition, damage by casualty
         and reasonable wear and tear only excepted, and all glass in windows
         (except glass in exterior walls unless the damage thereto is
         attributable to Tenant's negligence or misuse) and doors of the
         Premises whole and in good condition with glass of similar type and
         quality as that injured or broken, damage by fire or taking under the
         power of eminent domain only excepted, and at the expiration or
         termination of this Lease peaceably to yield up the Premises all
         construction, work, improvements, and all alterations and additions
         thereto in good order, repair and condition, reasonable wear and tear
         only excepted, first removing all goods and effects of Tenant and, to
         the extent specified by Landlord by notice to Tenant given at the time
         Landlord approves Tenant's plans for the installation of the same that
         removal will be required upon the expiration or earlier termination of
         the Lease Term, the wiring for Tenant's computer, telephone and other
         communication systems and equipment whether located in the Premises or
         in any other portion of the Building, including all risers and all
         alterations and additions made by Tenant and all partitions. Tenant
         shall repair any damage caused by such removal and shall restore the
         Premises and leave them clean and neat. Tenant shall not permit or
         commit any waste, and Tenant shall be responsible for the cost of
         repairs which may be made necessary by reason of damage to common areas
         in the Building or to the Site caused by Tenant, Tenant's agents,
         contractors, employees, sublessees, licensees, concessionaires or
         invitees.

5.3      USE.
         ---

         Continuously from the commencement of the Term, to use and occupy the
         Premises for the Permitted Use only, and not to injure or deface the
         Premises, Building, the Site or any other part of the Complex nor to
         permit in the Premises or on the Site any auction sale, vending machine
         (except for two (2) vending machines exclusively for use by Tenant's
         employees, one per on each floor occupied by Tenant; provided, however,
         that (i) Landlord shall have the right to approve the location of each
         such vending machine and (ii) Tenant shall be required to remove the
         vending machines upon the expiration or earlier termination of this
         Lease and repair any damage to the Premises caused by their
         installation and removal), or inflammable fluids or chemicals, or
         nuisance, or the emission from the Premises of any objectionable noise
         or odor, nor to permit in the Premises anything which will in any way
         result in the leakage of fluid or the growth of mold, and not to use or
         devote the Premises or any part thereof for any purpose other than the
         Permitted Uses, nor for any use thereof which is inconsistent with
         maintaining the Building as a first class office building in the
         quality of its maintenance, use and occupancy, or which is improper,
         offensive, contrary to law or ordinance or liable to render necessary
         any alteration or addition to the Building. Further, (i) Tenant shall
         not,


                                      -19-


<Page>


         nor shall Tenant permit its employees, invitees, agents, independent
         contractors, contractors, assignees or subtenants to, keep, maintain,
         store or dispose of (into the sewage or waste disposal system or
         otherwise) or engage in any activity which might produce or generate
         any substance which is or may hereafter be classified as a hazardous
         material, waste or substance (collectively "Hazardous Materials"),
         under federal, state or local laws, rules and regulations, including,
         without limitation, 42 U.S.C. Section 6901 et seq., 42 U.S.C. Section
         9601 et seq., 42 U.S.C. Section 2601 et seq., 49 U.S.C. Section 1802
         et seq. and Massachusetts General Laws, Chapter 21E and the rules and
         regulations promulgated under any of the foregoing, as such laws,
         rules and regulations may be amended from time to time (collectively
         "Hazardous Materials Laws"), (ii) Tenant shall immediately notify
         Landlord of any incident in, on or about the Premises, the Building or
         the Site that would require the filing of a notice under any Hazardous
         Materials Laws, (iii) Tenant shall comply and shall cause its
         employees, invitees, agents, independent contractors, contractors,
         assignees and subtenants to comply with each of the foregoing and (iv)
         Landlord shall have the right upon forty-eight (48) hours notice
         (except in the event of an emergency) to make such inspections
         (including testing) as Landlord shall reasonably determine are
         necessary from time to time to determine that Tenant is complying with
         the foregoing.

5.4      OBSTRUCTIONS; ITEMS VISIBLE FROM EXTERIOR; RULES AND REGULATIONS.
         ----------------------------------------------------------------

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

5.5      SAFETY APPLIANCES.
         -----------------

         To keep the Premises equipped with all safety appliances required by
         any public authority because of any use made by Tenant other than for
         Tenant's Permitted Use, and to procure all licenses and permits so
         required because of such use and, if requested by Landlord, to do any
         work so required because of such use, it being understood that the
         foregoing provisions shall not be construed to broaden in any way
         Tenant's Permitted Use.

5.6      ASSIGNMENT; SUBLEASE.
         --------------------

         Except as otherwise expressly provided herein, Tenant covenants and
         agrees that it shall not assign, mortgage, pledge, hypothecate or
         otherwise transfer this Lease and/or Tenant's interest in this Lease or
         sublet (which term, without limitation, shall include granting of
         concessions, licenses or the like) the whole or any part of the
         Premises. Any assignment, mortgage, pledge, hypothecation, transfer or
         subletting not expressly


                                      -20-


<Page>


         permitted in or consented to by Landlord under Sections 5.6.1-5.6.6
         shall be void, ab initio; shall be of no force and effect; and shall
         confer no rights on or in favor of third parties. In addition,
         Landlord shall be entitled to seek specific performance of or other
         equitable relief with respect to the provisions hereof.

         5.6.1 Notwithstanding the provisions of Section 5.6 above and the
               provisions of Section 5.6.2, 5.6.3 and 5.6.5 below, Tenant shall
               have the right to assign this Lease or to sublet the Premises (in
               whole or in part) to any parent or subsidiary corporation of
               Tenant or to any corporation into which Tenant may be converted
               or with which it may merge, provided that the entity to which
               this Lease is so assigned or which so sublets the Premises has a
               credit worthiness (e.g. assets on a pro forma basis using
               generally accepted accounting principles consistently applied and
               using the most recent financial statements) which is the same or
               better than Tenant as of the date of this Lease. If any parent or
               subsidiary corporation of Tenant to which this Lease is assigned
               or the Premises sublet (in whole or in part) shall cease to be
               such a parent or subsidiary corporation, such cessation shall be
               considered an assignment or subletting requiring Landlord's
               consent, which consent shall not be unreasonably withheld,
               delayed or conditioned. Any such assignment or subletting shall
               be subject to the provisions of Section 5.6.4 and Section 5.6.6
               below.

         5.6.2 Notwithstanding the provisions of Section 5.6 above, in the
               event Tenant desires to assign this Lease or to sublet the
               Premises (in whole or in part), Tenant shall give Landlord a
               Proposed Transfer Notice (as defined in Section 5.6.4 hereof) and
               Landlord shall have the right at its sole option, to be exercised
               within fifteen (15) days after receipt of Tenant's Proposed
               Transfer Notice (the "Acceptance Period"), to terminate this
               Lease as of a date specified in a notice to Tenant, which date
               shall not be earlier than sixty (60) days nor later than one
               hundred and twenty (120) days after Landlord's notice to Tenant;
               provided, however, that upon the termination date as set forth in
               Landlord's notice, all obligations relating to the period after
               such termination date (but not those relating to the period
               before such termination date) shall cease and promptly upon being
               billed therefor by Landlord, Tenant shall make final payment of
               all rent and Additional Rent due from Tenant through the
               termination date. Notwithstanding the foregoing, in the event
               that Tenant shall propose to sublease a portion of the Premises,
               Landlord shall only have the right to so terminate this Lease
               with respect to the portion of the Premises which Tenant proposes
               to sublease (the "Terminated Portion of the Premises") and from
               and after the termination date the Rentable Floor Area of the
               Premises shall be reduced to the rentable floor area of the
               remainder of the Premises and the definition of Rentable Floor
               Area of the Premises shall be so amended and after such
               termination all references in this Lease to the "Premises" or the
               "Rentable Floor Area of the Premises" shall be deemed to be
               references to the remainder of the Premises and accordingly
               Tenant's payments for Annual Fixed Rent, operating costs, real
               estate taxes and electricity shall be reduced on a pro rata basis
               to reflect the size of the remainder of the Premises.


                                      -21-


<Page>


               In the event that Landlord elects to terminate this Lease as
               aforesaid, Tenant shall have the right upon written notice
               delivered to Landlord within fifteen (15) days from receipt of
               Landlord's termination notice, to rescind its Proposed Transfer
               Notice, at which point Landlord's termination notice shall be
               deemed null and void and this Lease shall continue in full force
               and effect.

               In the event that Landlord shall not exercise its termination
               rights as aforesaid, or shall fail to give any or timely notice
               pursuant to this Section the provisions of Sections 5.6.3-5.6.6
               shall be applicable. This Section 5.6.2 shall not be applicable
               to an assignment or sublease pursuant to Section 5.6.1.

         5.6.3 Notwithstanding the provisions of Section 5.6 above, but subject
               to the provisions of this Section 5.6.3 and the provisions of
               Sections 5.6.4, 5.6.5 and 5.6.6 below, in the event that Landlord
               shall not have exercised the termination right as set forth in
               Section 5.6.2, or shall have failed to give any or timely notice
               under Section 5.6.2, then for a period of ninety (90) days (i)
               after the receipt of Landlord's notice stating that Landlord does
               not elect the termination right, or (ii) after the expiration of
               the Acceptance Period in the event Landlord shall not give any or
               timely notice pursuant to Section 5.6.2, as the case may be,
               Tenant shall have the right to assign this Lease or sublet the
               Premises in accordance with the Proposed Transfer Notice given as
               provided in Section 5.6.4 provided that, in each instance, Tenant
               first obtains the express prior written consent of Landlord,
               which consent shall not be unreasonably withheld or delayed.
               Without limiting the foregoing standard, Landlord shall not be
               deemed to be unreasonably withholding its consent to such a
               proposed assignment or subleasing if:

               (a)  if Landlord has comparable space available for lease in the
                    Building, the proposed assignee or subtenant is a tenant in
                    the Building or is in active negotiation with Landlord for
                    premises in the Building, or

               (b)  the proposed assignee or subtenant is not of good character
                    and reputation or is not of a character consistent with the
                    operation of a first class office building (by way of
                    example Landlord shall not be deemed to be unreasonably
                    withholding its consent to an assignment or subleasing to
                    any governmental or quasi-governmental agency which is open
                    to the public), or

               (c)  the proposed assignee does not possess adequate financial
                    capability to perform the Tenant obligations as and when due
                    or required or the proposed subtenant does not possess
                    adequate financial capability to perform the subtenant
                    obligations under the sublease as and when due or required,
                    or

               (d)  the assignee or subtenant proposes to use the Premises (or
                    part thereof) for a purpose other than the purpose for which
                    the Premises may be used as stated in Section 1.1 hereof, or


                                      -22-


<Page>


               (e)  the character of the business to be conducted or the
                    proposed use of the Premises by the proposed subtenant or
                    assignee shall (i) be likely to increase Landlord's
                    Operating Expenses beyond that which Landlord now incurs for
                    use by Tenant; (ii) be likely to increase the burden on
                    elevators or other Building systems or equipment over the
                    burden prior to such proposed subletting or assignment; or
                    (iii) violate or be likely to violate any provisions or
                    restrictions contained herein relating to the use or
                    occupancy of the Premises, or

               (f)  there shall be existing an Event of Default (defined in
                    Section 7.1), or

               (g)  any part of the rent payable under the proposed assignment
                    or sublease shall be based in whole or in part on the income
                    or profits derived from the Premises or if any proposed
                    assignment or sublease shall potentially have any adverse
                    effect on the real estate investment trust qualification
                    requirements applicable to Landlord and its affiliates, or

               (h)  the holder of any mortgage or ground lease on property which
                    includes the Premises does not approve of the proposed
                    assignment or sublease, or

               (i)  due to the identity or business of a proposed assignee or
                    subtenant, such approval would cause Landlord to be in
                    violation of any covenant or restriction contained in
                    another lease or other agreement affecting space in the
                    Building or elsewhere in the Property.

         5.6.4 Tenant shall give Landlord notice (the "Proposed Transfer
               Notice") of any proposed sublease or assignment, and said notice
               shall specify the provisions of the proposed assignment or
               subletting, including (a) the name and address of the proposed
               assignee or subtenant, (b) in the case of a proposed assignment
               or subletting pursuant to Section 5.6.2, such information as to
               the proposed assignee's or proposed subtenant's net worth and
               financial capability and standing as may reasonably be required
               for Landlord to make the determination referred to in Section
               5.6.3 above (provided, however, that Landlord shall hold such
               information confidential having the right to release same to its
               officers, accountants, attorneys and mortgage lenders on a
               confidential basis), (c) all of the terms and provisions upon
               which the proposed assignment or subletting is to be made, (d) in
               the case of a proposed assignment or subletting pursuant to
               Section 5.6.2, all other information necessary to make the
               determination referred to in Section 5.6.3 above and (e) in the
               case of a proposed assignment or subletting pursuant to Section
               5.6.1 above, such information as may be reasonably required by
               Landlord to determine that such proposed assignment or subletting
               complies with the requirements of said Section 5.6.1.

               If Landlord shall consent to the proposed assignment or
               subletting, as the case may be, then, in such event, Tenant may
               thereafter sublease or assign pursuant to


                                      -23-


<Page>


               Tenant's notice, as given hereunder; provided, however, that if
               such assignment or sublease shall not be executed and delivered
               to Landlord within ninety (90) days after the date of Landlord's
               consent, the consent shall be deemed null and void and the
               provisions of Section 5.6.2 shall be applicable.

         5.6.5 In addition, in the case of any assignment or subleasing as to
               which Landlord may consent (other than an assignment or
               subletting permitted under Section 5.6.1 hereof) such consent
               shall be upon the express and further condition, covenant and
               agreement, and Tenant hereby covenants and agrees that, in
               addition to the Annual Fixed Rent, Additional Rent and other
               charges to be paid pursuant to this Lease, fifty percent (50%) of
               the "Assignment/Sublease Profits" (hereinafter defined), if any,
               shall be paid to Landlord.

               The "Assignment/Sublease Profits" shall be the excess, if any, of
               (a) the "Assignment/Sublease Net Revenues" as hereinafter defined
               over (b) the Annual Fixed Rent and Additional Rent and other
               charges provided in this Lease. The "Assignment/Sublease Net
               Revenues" shall be the fixed rent, Additional Rent and all other
               charges and sums paid either initially or over the term of the
               sublease or assignment plus all other profits and increases to be
               derived by Tenant as a result of such subletting or assignment,
               less the reasonable costs of Tenant incurred in such subleasing
               or assignment (the definition of which shall be limited to rent
               concessions, brokerage commissions, legal fees and alteration
               allowances, in each case actually paid), as set forth in a
               statement certified by an appropriate officer of Tenant and
               delivered to Landlord within thirty (30) days of the full
               execution of the sublease or assignment document, amortized over
               the term of the sublease or assignment (it being understood and
               agreed that said statement may set forth costs that are not
               required to be paid within said thirty-day period, so long as the
               obligation to pay the same has been incurred such that the costs
               are known at the time the statement is prepared).

               All payments of the Assignment/Sublease Profits due Landlord
               shall be made within ten (10) days of receipt of same by Tenant.

         5.6.6 (A) It shall be a condition of the validity of any assignment or
               subletting of right under Section 5.6.1 above, or consented to
               under Section 5.6.3 above, that the assignee or sublessee enter
               into a separate written instrument directly with Landlord in a
               form and containing terms and provisions reasonably satisfactory
               to Landlord to be bound directly to Landlord for all the
               obligations of the tenant hereunder, including, without
               limitation, the obligation (a) to pay the rent and other amounts
               provided for under this Lease (but in the case of a partial
               subletting pursuant to Section 5.6.1, such subtenant shall agree
               on a pro rata basis to be so bound) and (b) to comply with the
               provisions of Sections 5.6 through 5.6.6 hereof. Such assignment
               or subletting shall not relieve the tenant named herein of any of
               the obligations of the tenant hereunder and Tenant shall remain
               fully and primarily liable therefor and the liability of Tenant
               and such assignee (or subtenant, as the case may be) shall be
               joint and several. Further, and


                                      -24-


<Page>


               notwithstanding the foregoing, the provisions hereof shall not
               constitute a recognition of the assignment or the assignee
               thereunder or the sublease or the subtenant thereunder, as the
               case may be, and at Landlord's option, upon the termination or
               expiration of the Lease (whether such termination is based upon a
               cause beyond Tenant's control, a default of Tenant, the agreement
               of Tenant and Landlord or any other reason), the assignment or
               sublease shall be terminated.

               (B) As Additional Rent Tenant shall pay to Landlord as a fee for
               Landlord's review of any proposed assignment or sublease
               requested by Tenant and the preparation of any associated
               documentation in connection therewith, within thirty (30) days
               after receipt of an invoice from Landlord, an amount equal to the
               sum of (i) $150.00 per hour for in-house staff and/or (ii)
               reasonable out of pocket legal fees or other expenses incurred by
               Landlord in connection with such request. In no event shall the
               total amount of such fee exceed $2,000.00 in connection with any
               single request for consent.

               (C) If this Lease be assigned, or if the Premises or any part
               thereof be sublet or occupied by anyone other than Tenant,
               Landlord may upon prior notice to Tenant, at any time and from
               time to time, collect rent and other charges from the assignee,
               sublessee or occupant and apply the net amount collected to the
               rent and other charges herein reserved, but no such assignment,
               subletting, occupancy or collection shall be deemed a waiver of
               this covenant, or a waiver of the provisions of Sections 5.6
               through 5.6.6 hereof, or the acceptance of the assignee,
               sublessee or occupant as a tenant or a release of Tenant from the
               further performance by Tenant of covenants on the part of Tenant
               herein contained, the Tenant herein named to remain primarily
               liable under this Lease.

               (D) The consent by Landlord to an assignment or subletting under
               any of the provisions of Sections 5.6.1 or 5.6.3 shall in no way
               be construed to relieve Tenant from obtaining the express consent
               in writing of Landlord to any further assignment or subletting.

               (E) On or after the occurrence of an "Event of Default" (defined
               in Section 7.1), Landlord shall be entitled to one hundred
               percent (100%) of any Assignment/Sublease Profits.

               (F) Without limiting Tenant's obligations under Section 5.14,
               Tenant shall be responsible, at Tenant's sole cost and expense,
               for performing all work necessary to comply with Legal
               Requirements and Insurance Requirements in connection with any
               assignment or subletting hereunder including, without limitation,
               any work in connection with such assignment or subletting.

               (G) In addition to the other requirements set forth in this Lease
               and notwithstanding any other provision of this Lease, partial
               sublettings of the Premises shall only be permitted under the
               following terms and conditions: (i) the layout of both the
               subleased premises and the remainder of the Premises must


                                      -25-


<Page>


               comply with applicable laws, ordinances, rules and/or regulations
               and be approved by Landlord (which such approval shall not be
               unreasonably withheld, conditioned or delayed), including,
               without limitation, all requirements concerning access and
               egress; (ii) in the event the subleased premises are separately
               physically demised from the remainder of the Premises, Tenant
               shall pay all reasonable costs of separately physically demising
               the subleased premises; and (iii) there shall be no more than two
               (2) subleases in effect for the Second Floor Premises and two (2)
               subleases in effect for the Third Floor Premises at any given
               time

5.7      INDEMNITY; INSURANCE.
         --------------------

         (A) INDEMNITY. To defend with counsel first approved by Landlord (which
         approval shall not be unreasonably withheld or delayed), save harmless,
         and indemnify Landlord from any liability for injury, loss, accident or
         damage to any person or property, and from any claims, actions,
         proceedings and expenses and costs in connection therewith (including
         without limitation reasonable counsel fees) (i) arising from or claimed
         to have arisen from (a) the omission, fault, willful act, negligence or
         other misconduct of Tenant or Tenant's contractors, licensees,
         invitees, agents, servants, independent contractors or employees or (b)
         any use made or thing done or occurring on the Premises not due to the
         omission, fault, willful act, negligence or other misconduct of
         Landlord or Landlord's contractors, licensees, agents, servants,
         independent contractors or employees, or (ii) resulting from the
         failure of Tenant to perform and discharge its covenants and
         obligations under this Lease.

         (B) INSURANCE. To maintain in full force from the date upon which
         Tenant first enters the Premises for any reason, throughout the Term of
         this Lease, and thereafter, so long as Tenant is in occupancy of any
         part of the Premises, commercial general liability insurance or
         comprehensive general liability insurance written on an occurrence
         basis with a broad form comprehensive liability endorsement under which
         Tenant is the named insured and Landlord and Landlord's managing agent
         (and such persons as are in privity of estate with Landlord and
         Landlord's managing agent as may be set out in notice from time to
         time) are named as additional insureds with limits which shall, at the
         commencement of the Term, be at least equal to those stated in Section
         1.1 and from time to time during the Term shall be for such higher
         limits, if any, as are customarily carried in the Boston West Suburban
         Market with respect to similar properties or which may reasonably be
         required by Landlord, and worker's compensation insurance with
         statutory limits covering all of Tenant's employees working in the
         Premises, and to deposit with Landlord on or before the earlier of the
         date Tenant enters the Premises or the Commencement Date and concurrent
         with all renewals thereof, certificates for such insurance bearing the
         endorsement that the policies will not be canceled until after thirty
         (30) days' written notice to Landlord. In addition, in the event Tenant
         hosts a function in the Premises, Tenant agrees to obtain and maintain,
         and cause any persons or parties providing services for such function
         to obtain, the appropriate insurance coverages as reasonably determined
         by Landlord (including liquor liability, if applicable) and provide
         Landlord with evidence of the same. All insurance required to be
         maintained by Tenant pursuant to this Lease shall be maintained with
         responsible companies qualified to do


                                      -26-


<Page>


         business, and in good standing, in the Commonwealth of Massachusetts
         and which have a rating of at least "A-" and are within a financial
         size category of not less than "Class VIII" in the most current Best's
         Key Rating Guide or such similar rating as may be reasonably selected
         by Landlord if such Guide is no longer published.

5.8      PERSONAL PROPERTY AT TENANT'S RISK.
         ----------------------------------

         That all of the furnishings, fixtures, equipment, effects and property
         of every kind, nature and description of Tenant and of all persons
         claiming by, through or under Tenant which, during the continuance of
         this Lease or any occupancy of the Premises by Tenant or anyone
         claiming under Tenant, may be on the Premises or elsewhere in the
         Building or on the Site, shall be at the sole risk and hazard of
         Tenant, and if the whole or any part thereof shall be destroyed or
         damaged by fire, water or otherwise, or by the leakage or bursting of
         water pipes, or other pipes, by theft or from any other cause, no part
         of said loss or damage is to be charged to or be borne by Landlord,
         except that Landlord shall in no event be indemnified or held harmless
         or exonerated from any liability to Tenant or to any other person, for
         any injury, loss, damage or liability to the extent such indemnity,
         hold harmless or exoneration is prohibited by law. Further, Tenant, at
         Tenant's expense, shall maintain at all times during the Term of this
         Lease business interruption insurance and insurance against loss or
         damage covered by so-called "all risk" type insurance coverage with
         respect to Tenant's fixtures, equipment, goods, wares and merchandise,
         tenant improvements made by or paid for by Tenant, and other property
         of Tenant (collectively "Tenant's Property"). Such insurance shall be
         in an amount at least equal to the full replacement cost of Tenant's
         Property. Tenant shall maintain all of its equipment, furniture and
         furnishings in good order and repair. In addition, during such time as
         Tenant is performing work in or to the Premises, Tenant, at Tenant's
         expense, shall also maintain builder's risk insurance for the full
         insurable value of such work.

5.9      RIGHT OF ENTRY.
         --------------

         To permit Landlord and its agents to examine the Premises at reasonable
         times and upon at least forty-eight (48) hours prior notice (except in
         the event of an emergency) and, if Landlord shall so elect, to make any
         repairs or replacements Landlord may deem necessary; to remove, at
         Tenant's expense, any alterations, addition, signs, curtains, blinds,
         shades, awnings, aerials, flagpoles, or the like not consented to in
         writing; and to show the Premises to prospective tenants during the six
         (6) months preceding expiration of the Term and to prospective
         purchasers and mortgagees at all reasonable times. Landlord and its
         agents shall use commercially reasonable efforts to minimize any
         unreasonable interference with Tenant's business operations and use of
         the Premises in the exercise of the foregoing rights, consistent with
         the reason for entry.

5.10     FLOOR LOAD; PREVENTION OF VIBRATION AND NOISE.
         ---------------------------------------------

         Not to place a load upon the Premises exceeding an average rate of 100
         pounds of live load per square foot of floor area (partitions shall be
         considered as part of the live load); and not to move any safe, vault
         or other heavy equipment in, about or out of the Premises except in
         such manner and at such time as Landlord shall in each instance
         authorize;


                                      -27-


<Page>


         Tenant's business machines and mechanical equipment which cause
         vibration or noise that may be transmitted to the Building structure
         or to any other space in the Building shall be so installed,
         maintained and used by Tenant so as to eliminate such vibration or
         noise.

5.11     PERSONAL PROPERTY TAXES.
         -----------------------

         To pay promptly when due all taxes which may be imposed upon Tenant's
         Property in the Premises to whomever assessed.

5.12     COMPLIANCE WITH LAWS.
         --------------------

         To comply with all applicable Legal Requirements now or hereafter in
         force which shall impose a duty on Landlord or Tenant relating to or as
         a result of the use or occupancy of the Premises; provided that Tenant
         shall not be required to make any alterations or additions to the
         structure, roof, exterior and load bearing walls, foundation,
         structural floor slabs and other structural elements of the Building
         unless the same are required by such Legal Requirements as a result of
         or in connection with Tenant's use or occupancy of the Premises beyond
         Tenant's Permitted Use. Tenant shall promptly pay all fines, penalties
         and damages that may arise out of or be imposed because of its failure
         to comply with the provisions of this Section 5.12.

         Landlord at Landlord's expense, shall be responsible for the Premises
         complying on the Commencement Date with the requirements of the Federal
         Americans With Disabilities Act (the "ADA") in effect on the
         Commencement Date; provided, however, that notwithstanding the
         foregoing, Tenant at Tenant's expense, shall be responsible for (i) any
         additions, alterations or improvements performed by or for Tenant or
         any assignee of subtenant of Tenant ("Tenant Improvements") complying
         with the ADA and (ii) compliance with the ADA required because of
         "Tenant's Specific Use of the Premises" (as defined below) or Tenant
         Improvements. The term "Tenant's Specific Use of the Premises" as used
         in this Lease shall not refer to the general office use of the
         Premises, but shall refer to the specific products and operations
         Tenant and any assignee and subtenant of Tenant use in the Premises and
         the manner in which Tenant and any assignee and subtenant of Tenant use
         such products and conduct such operations.

5.13     PAYMENT OF LITIGATION EXPENSES.
         ------------------------------

         To pay as Additional Rent all reasonable costs, counsel and other fees
         incurred by Landlord in connection with the successful enforcement by
         Landlord of any obligations of Tenant under this Lease or in connection
         with any bankruptcy case involving Tenant or any guarantor.

5.14     ALTERATIONS.
         -----------

         Tenant shall not make alterations and additions to Tenant's space
         except in accordance with plans and specifications therefor first
         approved by Landlord, which approval shall not be unreasonably
         withheld. However, Landlord's determination of matters relating to


                                      -28-


<Page>


         aesthetic issues relating to alterations, additions or improvements
         which are visible outside the Premises shall be in Landlord's sole
         discretion. Without limiting such standard Landlord shall not be deemed
         unreasonable for withholding approval of any alterations or additions
         (including, without limitation, any alterations or additions to be
         performed by Tenant under Article III) which (a) in Landlord's opinion
         might adversely affect any structural or exterior element of the
         Building, any area or element outside of the Premises, or any facility
         or base building mechanical system serving any area of the Building
         outside of the Premises, or (b) involve or affect the exterior design,
         size, height, or other exterior dimensions of the Building or (c) will
         require unusual expense to readapt the Premises to normal office use on
         Lease termination or expiration or increase the cost of construction or
         of insurance or taxes on the Building or of the services called for by
         Section 4.1 unless Tenant first gives assurance acceptable to Landlord
         for payment of such increased cost and that such readaptation will be
         made prior to such termination or expiration without expense to
         Landlord, (d) enlarge the Rentable Floor Area of the Premises, or (e)
         are inconsistent, in Landlord's judgment, with alterations satisfying
         Landlord's standards for new alterations in the Building. Landlord's
         review and approval of any such plans and specifications and consent to
         perform work described therein shall not be deemed an agreement by
         Landlord that such plans, specifications and work conform with
         applicable Legal Requirements and requirements of insurers of the
         Building and the other requirements of this Lease with respect to
         Tenant's insurance obligations (herein called "Insurance Requirements")
         nor deemed a waiver of Tenant's obligations under this Lease with
         respect to applicable Legal Requirements and Insurance Requirements nor
         impose any liability or obligation upon Landlord with respect to the
         completeness, design sufficiency or compliance of such plans,
         specifications and work with applicable Legal Requirements and
         Insurance Requirements nor give right to any other parties. Further,
         Tenant acknowledges that Tenant is acting for its own benefit and
         account, and that Tenant shall not be acting as Landlord's agent in
         performing any work in the Premises. Within thirty (30) days after
         receipt of an invoice from Landlord, Tenant shall pay to Landlord as a
         fee for Landlord's review of any work or plans (excluding any review
         respecting initial improvements performed pursuant to Article III
         hereof for which a fee, if any, has previously been paid but including
         any review of plans or work relating to any assignment or subletting),
         as Additional Rent, an amount equal to the sum of: (i) $150.00 per
         hour, plus (ii) third party expenses incurred by Landlord to review
         Tenant's plans and Tenant's work. All alterations and additions shall
         be part of the Building unless and until Landlord shall specify the
         same for removal pursuant to Section 5.2. All of Tenant's alterations
         and additions and installation of furnishings shall be coordinated with
         any work being performed by Landlord and in such manner as to maintain
         harmonious labor relations and not to damage the Buildings or Site or
         interfere with construction or operation of the Buildings and other
         improvements to the Site and, except for installation of furnishings,
         shall be performed by Landlord's general contractor or by contractors
         or workers first approved by Landlord. Except for work by Landlord's
         general contractor, Tenant, before its work is started, shall secure
         all licenses and permits necessary therefor; deliver to Landlord a
         statement of the names of all its contractors and subcontractors and
         the estimated cost of all labor and material to be furnished by them
         and security satisfactory to Landlord protecting Landlord against liens
         arising out of the furnishing of such labor and material; and cause
         each contractor to carry workmen's


                                      -29-


<Page>


         compensation insurance in statutory amounts covering all the
         contractor's and subcontractor's employees and commercial general
         liability insurance or comprehensive general liability insurance with
         a broad form comprehensive liability endorsement with such limits as
         Landlord may reasonably require, but in no event less than
         $2,000,000.00 combined single limit per occurrence on a per location
         basis (all such insurance to be written in companies approved by
         Landlord and naming and insuring Landlord and Landlord's managing
         agent as additional insureds and insuring Tenant as well as the
         contractors), and to deliver to Landlord certificates of all such
         insurance. Tenant shall also prepare and submit to Landlord a set of
         as-built plans (or, in cases where the alterations, additions or
         improvements at issue are not of such a nature that as-built plans
         would customarily be prepared or otherwise be reasonably practicable
         to obtain, detailed drawings and specifications), in both print and
         electronic forms, showing such work performed by Tenant to the
         Premises promptly after any such alterations, improvements or
         installations are substantially complete and promptly after any wiring
         or cabling for Tenant's computer, telephone and other communications
         systems is installed by Tenant or Tenant's contractor. Without
         limiting any of Tenant's obligations hereunder, Tenant shall be
         responsible, as Additional Rent, for the costs of any alterations,
         additions or improvements in or to the Building that are required in
         order to comply with Legal Requirements as a result of any work
         performed by Tenant. Landlord shall have the right to provide such
         rules and regulations relative to the performance of any alterations,
         additions, improvements and installations by Tenant hereunder and
         Tenant shall abide by all such reasonable rules and regulations and
         shall cause all of its contractors to so abide including, without
         limitation, payment for the costs of using Building services. Tenant
         agrees to pay promptly when due the entire cost of any work done on
         the Premises by Tenant, its agents, employees, or independent
         contractors, and not to cause or permit any liens for labor or
         materials performed or furnished in connection therewith to attach to
         the Premises or the Buildings or the Site and immediately to discharge
         any such liens which may so attach. Tenant shall pay, as Additional
         Rent, 100% of any real estate taxes on the Complex which shall, at any
         time after commencement of the Term, result from any alteration,
         addition or improvement to the Premises made by Tenant.

5.15     VENDORS.
         --------

         Any vendors engaged by Tenant to perform services in or to the Premises
         including, without limitation, janitorial contractors and moving
         contractors shall be coordinated with any work being performed by or
         for Landlord and in such manner as to maintain harmonious labor
         relations and not to damage the Building or the Property or interfere
         with Building construction or operation and shall be performed by
         vendors first approved by Landlord.


                                      -30-


<Page>


                                   ARTICLE VI
                                   ----------

                               CASUALTY AND TAKING
                               -------------------

6.1      DAMAGE RESULTING FROM CASUALTY.
         ------------------------------

         In case during the Lease Term, the Premises and/or the Building are
         damaged by fire or casualty and such fire or casualty damage cannot, in
         the ordinary course, reasonably be expected to be repaired within one
         hundred eighty (180) days (and/or as to special work or work which
         requires long lead time then if such work cannot reasonably be expected
         to be repaired within such additional time as is reasonable under the
         circumstances given the nature of the work) from the time that repair
         work would commence, either party may, at its election, terminate this
         Lease by notice given to the other party within sixty (60) days after
         the date of such fire or other casualty, specifying the effective date
         of termination. The effective date of termination specified by the
         terminating party shall be not less than thirty (30) days nor more than
         forty-five (45) days after the date of notice of such termination.

         Unless terminated pursuant to the foregoing provisions, this Lease
         shall remain in full force and effect following any such damage
         subject, however, to the following provisions.

         If the Building or the Site or any part thereof are damaged by fire or
         other casualty and this Lease is not so terminated, or Landlord or
         Tenant have no right to terminate this Lease, and in any such case the
         holder of any mortgage which includes the Building as a part of the
         mortgaged premises or any ground lessor of any ground lease which
         includes the Site as part of the demised premises allows the net
         insurance proceeds to be applied to the restoration of the Building
         (and/or the Site), Landlord shall, promptly after such damage and the
         determination of the net amount of insurance proceeds available, use
         due diligence to restore the Premises and the Building in the event of
         damage thereto (excluding Tenant's Property) into substantially the
         same condition as they were in prior to the fire or casualty and a just
         proportion of the Annual Fixed Rent, Tenant's share of Operating Costs
         and Tenant's share of real estate taxes shall be abated according to
         the nature and extent of the injury to the Premises, until the Premises
         shall have been restored by Landlord substantially into such condition
         except for punch list items and long lead items. Notwithstanding
         anything herein contained to the contrary, Landlord shall not be
         obligated to expend for such repair and restoration any amount in
         excess of the net insurance proceeds.

         If such restoration is not completed within six (6) months from the
         time that repair work commences, such period to be subject, however, to
         extension where the delay in completion of such work is due to Force
         Majeure, as defined hereinbelow, (but in no event beyond ten (10)
         months from the date of the fire or casualty), Tenant, as its sole and
         exclusive remedy, shall have the right to terminate this Lease at any
         time after the expiration of such six-month period (as extended), which
         right shall continue until the restoration is substantially completed.
         Such termination shall be effective as of the thirtieth (30th) day
         after the date of receipt by Landlord of Tenant's notice, with the same


                                      -31-


<Page>


         force and effect as if such date were the date originally established
         as the expiration date hereof unless, within thirty (30) days after
         Landlord's receipt of Tenant's notice, such restoration is
         substantially completed, in which case Tenant's notice of termination
         shall be of no force and effect and this Lease and the Lease Term shall
         continue in full force and effect. When used herein, "Force Majeure"
         shall mean any prevention, delay or stoppage due to governmental
         regulation, strikes, lockouts, acts of God, acts of war, terrorists
         acts, civil commotions, unusual scarcity of or inability to obtain
         labor or materials, labor difficulties, casualty or other causes
         reasonably beyond Landlord's control or attributable to Tenant's action
         or inaction.

6.2      UNINSURED CASUALTY.
         ------------------

         Notwithstanding anything to the contrary contained in this Lease, if
         the Building or the Premises shall be substantially damaged by fire or
         casualty as the result of a risk not covered by the forms of casualty
         insurance at the time maintained by Landlord and such fire or casualty
         damage cannot, in the ordinary course, reasonably be expected to be
         repaired within ninety (90) days from the time that repair work would
         commence, Landlord may, at its election, terminate the Term of this
         Lease by notice to the Tenant given within sixty (60) days after such
         loss. If Landlord shall give such notice, then this Lease shall
         terminate as of the date of such notice with the same force and effect
         as if such date were the date originally established as the expiration
         date hereof.

6.3      RIGHTS OF TERMINATION FOR TAKING.
         --------------------------------

         If the entire Building, or such portion of the Premises as to render
         the balance (if reconstructed to the maximum extent practicable in the
         circumstances) unsuitable for Tenant's purposes, shall be taken by
         condemnation or right of eminent domain, Landlord or Tenant shall have
         the right to terminate this Lease by notice to the other of its desire
         to do so, provided that such notice is given not later than thirty (30)
         days after Tenant has been deprived of possession. If either party
         shall give such notice, then this Lease shall terminate as of the date
         of such notice with the same force and effect as if such date were the
         date originally established as the expiration date hereof.

         Further, if so much of the Building shall be so taken that continued
         operation of the Building would be uneconomic as a result of the
         taking, Landlord shall have the right to terminate this Lease by giving
         notice to Tenant of Landlord's desire to do so not later than thirty
         (30) days after Tenant has been deprived of possession of the Premises
         (or such portion thereof as may be taken). If Landlord shall give such
         notice, then this Lease shall terminate as of the date of such notice
         with the same force and effect as if such date were the date originally
         established as the expiration date hereof.

         Should any part of the Premises be so taken or condemned during the
         Lease Term hereof, and should this Lease not be terminated in
         accordance with the foregoing provisions, and the holder of any
         mortgage which includes the Premises as part of the mortgaged premises
         or any ground lessor of any ground lease which includes the Site as
         part of the demised premises allows the net condemnation proceeds to be
         applied to the restoration of the Building, Landlord agrees, after the
         determination of the net amount of


                                      -32-


<Page>


         condemnation proceeds available to Landlord, to use due diligence to
         put what may remain of the Premises into proper condition for use and
         occupation as nearly like the condition of the Premises prior to such
         taking as shall be practicable (excluding Tenant's Property).
         Notwithstanding the foregoing, Landlord shall not be obligated to
         expend for such repair and restoration any amount in excess of the net
         condemnation proceeds made available to it.

         If the Premises shall be affected by any exercise of the power of
         eminent domain, then the Annual Fixed Rent, Tenant's share of operating
         costs and Tenant's share of real estate taxes shall be justly and
         equitably abated and reduced according to the nature and extent of the
         loss of use thereof suffered by Tenant; and in case of a taking which
         permanently reduces the Rentable Floor Area of the Premises, a just
         proportion of the Annual Fixed Rent, Tenant's share of operating costs
         and Tenant's share of real estate taxes shall be abated for the
         remainder of the Lease Term.

6.4      AWARD.
         -----

         Landlord shall have and hereby reserves to itself any and all rights to
         receive awards made for damages to the Premises, the Building, the
         Complex and the Site and the leasehold hereby created, or any one or
         more of them, accruing by reason of exercise of eminent domain or by
         reason of anything lawfully done in pursuance of public or other
         authority. Tenant hereby grants, releases and assigns to Landlord all
         Tenant's rights to such awards, and covenants to execute and deliver
         such further assignments and assurances thereof as Landlord may from
         time to time request, and if Tenant shall fail to execute and deliver
         the same within fifteen (15) days after notice from Landlord, Tenant
         hereby covenants and agrees that Landlord shall be irrevocably
         designated and appointed as its attorney-in-fact to execute and deliver
         in Tenant's name and behalf all such further assignments thereof which
         conform with the provisions hereof.

         Nothing contained herein shall be construed to prevent Tenant from
         prosecuting in any condemnation proceeding a claim for the value of any
         of Tenant's usual trade fixtures installed in the Premises by Tenant at
         Tenant's expense and for relocation and moving expenses, provided that
         such action and any resulting award shall not affect or diminish the
         amount of compensation otherwise recoverable by Landlord from the
         taking authority.

                                   ARTICLE VII
                                   -----------

                                     DEFAULT
                                     -------

7.1      TENANT'S DEFAULT.
         ----------------

          (a)  If at any time subsequent to the date of this Lease any one or
               more of the following events (herein sometimes called an "Event
               of Default") shall occur:

                    (i)  Tenant shall fail to pay the fixed rent, Additional
                         Rent or other charges for which provision is made
                         herein on or before the date


                                      -33-


<Page>


                         on which the same become due and payable, and the same
                         continues for seven (7) days after notice from Landlord
                         thereof; or

                    (ii) Landlord having rightfully given the notice specified
                         in subdivision (i) above twice in any calendar year,
                         Tenant shall thereafter in the same calendar year fail
                         to pay the fixed rent, Additional Rent or other charges
                         on or before the date on which the same become due and
                         payable; or

                   (iii) Tenant shall assign its interest in this Lease or
                         sublet any portion of the Premises in violation of the
                         requirements of Section 5.6 through 5.6.5 of this
                         Lease; or

                    (iv) Tenant shall neglect or fail to perform or observe any
                         other covenant herein contained on Tenant's part to be
                         performed or observed and Tenant shall fail to remedy
                         the same within thirty (30) days after notice to Tenant
                         specifying such neglect or failure, or if such failure
                         is of such a nature that Tenant cannot reasonably
                         remedy the same within such thirty (30) day period,
                         Tenant shall fail to commence promptly to remedy the
                         same and to prosecute such remedy to completion with
                         diligence and continuity; or

                    (v)  Tenant's leasehold interest in the Premises shall be
                         taken on execution or by other process of law directed
                         against Tenant; or

                    (vi) Tenant shall make an assignment for the benefit of
                         creditors or shall file a voluntary petition in
                         bankruptcy or shall be adjudicated bankrupt or
                         insolvent, or shall file any petition or answer seeking
                         any reorganization, arrangement, composition,
                         readjustment, liquidation, dissolution or similar
                         relief for itself under any present or future Federal,
                         State or other statute, law or regulation for the
                         relief of debtors, or shall seek or consent to or
                         acquiesce in the appointment of any trustee, receiver
                         or liquidator of Tenant or of all or any substantial
                         part of its properties, or shall admit in writing its
                         inability to pay its debts generally as they become
                         due; or

                   (vii) A petition shall be filed against Tenant in bankruptcy
                         or under any other law seeking any reorganization,
                         arrangement, composition, readjustment, liquidation,
                         dissolution, or similar relief under any present or
                         future Federal, State or other statute, law or
                         regulation and shall remain undismissed or unstayed for
                         an aggregate of ninety (90) days (whether or not
                         consecutive), or if any debtor in possession (whether
                         or not Tenant) trustee, receiver or liquidator of
                         Tenant or of all or any substantial part of its
                         properties or of the Premises shall be appointed
                         without the consent or acquiescence of


                                      -34-


<Page>


                         Tenant and such appointment shall remain unvacated or
                         unstayed for an aggregate of ninety (90) days (whether
                         or not consecutive)--

               then, and in any of said cases (notwithstanding any license of a
               former breach of covenant or waiver of the benefit hereof or
               consent in a former instance), Landlord lawfully may, immediately
               or at any time thereafter, and without demand or further notice
               terminate this Lease by written notice to Tenant, specifying a
               date not less than ten (10) days after the giving of such notice
               on which this Lease shall terminate, and this Lease shall come to
               an end on the date specified therein as fully and completely as
               if such date were the date herein originally fixed for the
               expiration of the Lease Term (Tenant hereby waiving any rights of
               redemption), and Tenant will then quit and surrender the Premises
               to Landlord, but Tenant shall remain liable as hereinafter
               provided.

         (b)   If this Lease shall have been terminated as provided in this
               Article, then Landlord may re- enter the Premises, either by
               force, summary proceedings, ejectment or otherwise, and remove
               and dispossess Tenant and all other persons and any and all
               property from the same, as if this Lease had not been made.

         (c)   In the event that this Lease is terminated under any of the
               provisions contained in Section 7.1 (a) or shall be otherwise
               terminated by breach of any obligation of Tenant, Tenant
               covenants and agrees forthwith to pay and be liable for, on the
               days originally fixed herein for the payment thereof, amounts
               equal to the several installments of rent and other charges
               reserved as they would, under the terms of this Lease, become due
               if this Lease had not been terminated or if Landlord had not
               entered or re-entered, as aforesaid, and whether the Premises be
               relet or remain vacant, in whole or in part, or relet for a
               period less than the remainder of the Term, and for the whole
               thereof, but in the event the Premises be relet by Landlord,
               Tenant shall be entitled to a credit in the net amount of rent
               and other charges received by Landlord in reletting, after
               deduction of all reasonable expenses incurred in reletting the
               Premises (including, without limitation, remodeling costs,
               brokerage fees and the like), and in collecting the rent in
               connection therewith, in the following manner:

                         Landlord agrees to use reasonable efforts to relet
                         the Premises after Tenant vacates the same in the
                         event that this Lease is terminated based upon a
                         default by Tenant hereunder. The marketing of the
                         Premises in a manner similar to the manner in which
                         Landlord markets other premises within Landlord's
                         control in the Building shall be deemed to have
                         satisfied Landlord's obligation to use "reasonable
                         efforts." In no event shall Landlord be required to
                         (i) solicit or entertain negotiations with any other
                         prospective tenants for the Premises until Landlord
                         obtains full and unappealable legal right to relet
                         the Premises free of any claim of Tenant, (ii) relet
                         the Premises before leasing other vacant space in the
                         Building, (iii) lease the Premises for a rental less
                         than the current fair market rental then prevailing
                         for similar office space in the Building, or (iv)
                         enter into a


                                      -35-


<Page>


                         lease with any proposed tenant that does
                         not have, in Landlord's reasonable opinion,
                         sufficient financial resources or operating
                         experience to operate the Premises in a first class
                         manner

                         Amounts received by Landlord after reletting shall
                         first be applied against such Landlord's expenses,
                         until the same are recovered, and until such
                         recovery, Tenant shall pay, as of each day when a
                         payment would fall due under this Lease, the amount
                         which Tenant is obligated to pay under the terms of
                         this Lease (Tenant's liability prior to any such
                         reletting and such recovery not in any way to be
                         diminished as a result of the fact that such
                         reletting might be for a rent higher than the rent
                         provided for in this Lease); when and if such
                         expenses have been completely recovered, the amounts
                         received from reletting by Landlord as have not
                         previously been applied shall be credited against
                         Tenant's obligations as of each day when a payment
                         would fall due under this Lease, and only the net
                         amount thereof shall be payable by Tenant. Further,
                         amounts received by Landlord from such reletting for
                         any period shall be credited only against obligations
                         of Tenant allocable to such period, and shall not be
                         credited against obligations of Tenant hereunder
                         accruing subsequent or prior to such period; nor
                         shall any credit of any kind be due for any period
                         after the date when the term of this Lease is
                         scheduled to expire according to its terms.

        (d)(i) At any time after such termination and whether or not Landlord
               shall have collected any damages as aforesaid, Tenant shall pay
               to Landlord as liquidated final damages and in lieu of all other
               damages beyond the date of notice from Landlord to Tenant, at
               Landlord's election, such a sum as at the time of the giving of
               such notice represents the amount of the excess, if any, of the
               total rent and other benefits which would have accrued to
               Landlord under this Lease from the date of such notice for what
               would be the then unexpired Lease Term if the Lease terms had
               been fully complied with by Tenant over and above the then cash
               rental value (in advance) of the Premises for the balance of the
               Lease Term.

       (d)(ii) For the purposes of this Article, if Landlord elects to
               require Tenant to pay damages in accordance with the immediately
               preceding paragraph, the total rent shall be computed by assuming
               that Tenant's share of excess taxes, Tenant's share of excess
               operating costs and Tenant's share of excess electrical costs
               would be, for the balance of the unexpired Term from the date of
               such notice, the amount thereof (if any) for the immediately
               preceding annual period payable by Tenant to Landlord.

          (e)  In case of any Event of Default, re-entry, dispossession by
               summary proceedings or otherwise, Landlord may (i) re-let the
               Premises or any part or parts thereof, either in the name of
               Landlord or otherwise, for a term or terms which may at
               Landlord's option be equal to or less than or exceed the period
               which would otherwise have constituted the balance of the Term of
               this Lease and may grant


                                      -36-


<Page>


               concessions or free rent to the extent that Landlord considers
               advisable or necessary to re-let the same and (ii) may make such
               alterations, repairs and decorations in the Premises as Landlord
               in its sole judgment considers advisable or necessary for the
               purpose of reletting the Premises; and the making of such
               alterations, repairs and decorations shall not operate or be
               construed to release Tenant from liability hereunder as
               aforesaid. Landlord shall in no event be liable in any way
               whatsoever for failure to re-let the Premises, or, in the event
               that the Premises are re-let, for failure to collect the rent
               under re-letting.

          (f)  The specified remedies to which Landlord may resort hereunder are
               not intended to be exclusive of any remedies or means of redress
               to which Landlord may at any time be entitled lawfully, and
               Landlord may invoke any remedy (including the remedy of specific
               performance) allowed at law or in equity as if specific remedies
               were not herein provided for. Further, nothing contained in this
               Lease shall limit or prejudice the right of Landlord to prove and
               obtain in proceedings for bankruptcy or insolvency by reason of
               the termination of this Lease, an amount equal to the maximum
               allowed by any statute or rule of law in effect at the time when,
               and governing the proceedings in which, the damages are to be
               proved, whether or not the amount be greater, equal to, or less
               than the amount of the loss or damages referred to above.

          (g)  In lieu of any other damages or indemnity and in lieu of the
               recovery by Landlord of all sums payable under all the foregoing
               provisions of this Section 7.1, Landlord may elect to collect
               from tenant, by notice to Tenant, at any time after this Lease is
               terminated under any of the provisions contained in this Article
               VII or otherwise terminated by breach of any obligation of Tenant
               and before such full recovery, and Tenant shall thereupon pay, as
               liquidated damages, an amount equal to the sum of the Annual
               Fixed Rent and all Additional Rent payable for the twelve (12)
               months ended next prior to the such termination plus the amount
               of Annual Fixed Rent and Additional Rent of any kind accrued and
               unpaid at the time of such election plus any and all expenses
               which the Landlord may have incurred for and with respect of the
               collection to any of such rent.

7.2      LANDLORD'S DEFAULT.
         ------------------

         Landlord shall in no event be in default in the performance of any of
         Landlord's obligations hereunder unless and until Landlord shall have
         failed to perform such obligations within thirty (30) days, or such
         additional time as is reasonably required to correct any such default,
         after notice by Tenant to Landlord properly specifying wherein Landlord
         has failed to perform any such obligation. The Tenant shall not assert
         any right to deduct the cost of repairs or any monetary claim against
         the Landlord from rent thereafter due and payable, but shall look
         solely to the Landlord for satisfaction of such claim.


                                      -37-


<Page>


                                  ARTICLE VIII
                                  ------------

                            MISCELLANEOUS PROVISIONS
                            ------------------------

8.1      EXTRA HAZARDOUS USE.
         -------------------

         Tenant covenants and agrees that Tenant will not do or permit anything
         to be done in or upon the Premises, or bring in anything or keep
         anything therein, which shall invalidate or increase the rate of
         insurance on the Premises or on the Building above the standard rate
         applicable to premises being occupied for the use to which Tenant has
         agreed to devote the Premises; and Tenant further agrees that, in the
         event that Tenant shall do any of the foregoing, Tenant will promptly
         pay to Landlord, on demand, any such increase resulting therefrom,
         which shall be due and payable as Additional Rent thereunder.

8.2      WAIVER.
         ------

         Failure on the part of Landlord or Tenant to complain of any action or
         non-action on the part of the other, no matter how long the same may
         continue, shall never be a waiver by Tenant or Landlord, respectively,
         of any of its rights hereunder. Further, no waiver at any time of any
         of the provisions hereof by Landlord or Tenant shall be construed as a
         waiver of any of the other provisions hereof, and a waiver at any time
         of any of the provisions hereof shall not be construed as a waiver at
         any subsequent time of the same provisions. The consent or approval of
         Landlord or Tenant to or of any action by the other requiring such
         consent or approval shall not be construed to waive or render
         unnecessary Landlord's or Tenant's consent or approval to or of
         subsequent similar act by the other.

         No payment by Tenant, or acceptance by Landlord, of a lesser amount
         than shall be due from Tenant to Landlord shall be treated otherwise
         than as a payment on account. The acceptance by Landlord of a check for
         a lesser amount with an endorsement or statement thereon, or upon any
         letter accompanying such check, that such lesser amount is payment in
         full, shall be given no effect, and Landlord may accept such check
         without prejudice to any other rights or remedies which Landlord may
         have against Tenant.

8.3      CUMULATIVE REMEDIES.
         -------------------

         Except as expressly provided in this Lease, the specific remedies to
         which Landlord may resort under the terms of this Lease are cumulative
         and are not intended to be exclusive of any other remedies or means of
         redress to which such party may be lawfully entitled in case of any
         breach or threatened breach by Tenant of any provisions of this Lease.
         In addition to the other remedies provided in this Lease, Landlord
         shall be entitled to the restraint by injunction of the violation or
         attempted or threatened violation of any of the covenants, conditions
         or provisions of this Lease or to a decree compelling specific
         performance of any such covenants, conditions or provisions.


                                      -38-


<Page>


8.4      QUIET ENJOYMENT.
         ---------------

         Tenant, subject to the terms and provisions of this Lease on payment of
         the rent and observing, keeping and performing all of the terms and
         provisions of this Lease on Tenant's part to be observed, kept and
         performed, shall lawfully, peaceably and quietly have, hold, occupy and
         enjoy the Premises during the Term (exclusive of any period during
         which Tenant is holding over after the termination or expiration of
         this Lease without the consent of Landlord), without hindrance or
         ejection by any persons lawfully claiming under Landlord to have title
         to the Premises superior to Tenant; the foregoing covenant of quiet
         enjoyment is in lieu of any other covenant, express or implied; and it
         is understood and agreed that this covenant and any and all other
         covenants of Landlord contained in this Lease shall be binding upon
         Landlord and Landlord's successors, including ground or master lessees,
         only with respect to breaches occurring during Landlord's or Landlord's
         successors' respective ownership of Landlord's interest hereunder, as
         the case may be.

         Further, Tenant specifically agrees to look solely to Landlord's then
         equity interest in the Building at the time owned, or in which Landlord
         holds an interest as ground lessee, for recovery of any judgment from
         Landlord; it being specifically agreed that neither Landlord (original
         or successor), nor any partner in or of Landlord, nor any beneficiary
         of any Trust of which any person holding Landlord's interest is
         trustee, nor any member, manager, partner, director or stockholder, nor
         Landlord's managing agent, shall ever be personally liable for any such
         judgment, or for the payment of any monetary obligation to Tenant. The
         provision contained in the foregoing sentence is not intended to, and
         shall not, limit any right that Tenant might otherwise have to obtain
         injunctive relief against Landlord or Landlord's successors in
         interest, or any action not involving the personal liability of
         Landlord (original or successor), any partner in or of Landlord, any
         successor trustee to the persons named herein as Landlord, or any
         beneficiary of any trust of which any person holding Landlord's
         interest is trustee, or of any manager, member, partner, director or
         stockholder of Landlord or of Landlord's managing agent to respond in
         monetary damages from Landlord's assets other than Landlord's equity
         interest aforesaid in the Building, but in no event shall Tenant have
         the right to terminate or cancel this Lease or to withhold rent or to
         set-off any claim or damages against rent as a result of any default by
         Landlord or breach by Landlord of its covenants or any warranties or
         promises hereunder, except in the case of a wrongful eviction of Tenant
         from the demised premises (constructive or actual) by Landlord
         continuing after notice to Landlord thereof and a reasonable
         opportunity for Landlord to cure the same. In no event shall Landlord
         ever be liable to Tenant for any indirect or consequential damages or
         loss of profits or the like. In the event that Landlord shall be
         determined to have acted unreasonably in withholding any consent or
         approval under this Lease, the sole recourse and remedy of Tenant in
         respect thereof shall be to specifically enforce Landlord's obligation
         to grant such consent or approval, and in no event shall the Landlord
         be responsible for any damages of whatever nature in respect of its
         failure to give such consent or approval nor shall the same otherwise
         affect the obligations of Tenant under this Lease or act as any
         termination of this Lease.


                                      -39-


<Page>


8.5      NOTICE TO MORTGAGEE AND GROUND LESSOR.
         -------------------------------------

         After receiving notice from any person, firm or other entity that it
         holds a mortgage which includes the Premises as part of the mortgaged
         premises, or that it is the ground lessor under a lease with Landlord,
         as ground lessee, which includes the Premises as a part of the demised
         premises, no notice from Tenant to Landlord shall be effective unless
         and until a copy of the same is given to such holder or ground lessor
         (provided Tenant has received written notice of such holder or ground
         lessor, including correct addresses, prior to the date Tenant sends its
         notice), and the curing of any of Landlord's defaults by such holder or
         ground lessor within a reasonable time thereafter (including a
         reasonable time to obtain possession of the premises if the mortgagee
         or ground lessor elects to do so) shall be treated as performance by
         Landlord. For the purposes of this Section 8.5 or Section 8.15, the
         term "mortgage" includes a mortgage on a leasehold interest of Landlord
         (but not one on Tenant's leasehold interest).

8.6      ASSIGNMENT OF RENTS.
         -------------------

         With reference to any assignment by Landlord or Landlord's interest in
         this Lease, or the rents payable hereunder, conditional in nature or
         otherwise, which assignment is made to the holder of a mortgage or
         ground lease on property which includes the Premises, Tenant agrees:

               (a)  That the execution thereof by Landlord, and the acceptance
                    thereof by the holder of such mortgage or the ground lessor,
                    shall never be treated as an assumption by such holder or
                    ground lessor of any of the obligations of Landlord
                    hereunder, unless such holder, or ground lessor, shall, by
                    notice sent to Tenant, specifically otherwise elect; and

               (b)  That, except as aforesaid, such holder or ground lessor
                    shall be treated as having assumed Landlord's obligations
                    hereunder only upon foreclosure of such holder's mortgage
                    and the taking of possession of the Premises, or, in the
                    case of a ground lessor, the assumption of Landlord's
                    position hereunder by such ground lessor.

         In no event shall the acquisition of title to the Building and the land
         on which the same is located by a purchaser which, simultaneously
         therewith, leases the entire Building or such land back to the seller
         thereof be treated as an assumption by such purchaser-lessor, by
         operation of law or otherwise, of Landlord's obligations hereunder, but
         Tenant shall look solely to such seller-lessee, and its successors from
         time to time in title, for performance of Landlord's obligations
         hereunder subject to the provisions of Section 8.4 hereof. In any such
         event, this Lease shall be subject and subordinate to the lease to such
         purchaser provided that such purchaser agrees to recognize the right of
         Tenant to use and occupy the Premises upon the payment of rent and
         other charges payable by Tenant under this Lease and the performance by
         Tenant of Tenant's obligations under this Lease and provided that
         Tenant agrees to attorn to such purchaser. For all purposes, such
         seller-lessee, and its successors in title, shall be the landlord
         hereunder unless and until Landlord's position shall have been assumed
         by such purchaser-lessor.


                                      -40-


<Page>


8.7      SURRENDER.
         ---------

         No act or thing done by Landlord during the Lease Term shall be deemed
         an acceptance of a surrender of the Premises, and no agreement to
         accept such surrender shall be valid, unless in writing signed by
         Landlord. No employee of Landlord or of Landlord's agents shall have
         any power to accept the keys of the Premises prior to the termination
         of this Lease. The delivery of keys to any employee of Landlord or of
         Landlord's agents shall not operate as a termination of the Lease or a
         surrender of the Premises.

8.8      BROKERAGE.
         ---------

         (A) Tenant warrants and represents that Tenant has not dealt with any
         broker, finder or other agent in connection with the consummation of
         this Lease other than the Recognized Broker, if any, designated in
         Section 1.1 hereof; and in the event any claim is made against the
         Landlord relative to dealings by Tenant with brokers, finders or other
         agents other than the Recognized Broker, if any, designated in Section
         1.1 hereof, Tenant shall defend the claim against Landlord with counsel
         of Tenant's selection first approved by Landlord (which approval will
         not be unreasonably withheld) and save harmless and indemnify Landlord
         on account of loss, cost or damage which may arise by reason of such
         claim.

         (B) Landlord warrants and represents that Landlord has not dealt with
         any broker, finder or other agent in connection with the consummation
         of this Lease other than the Recognized Broker, if any, designated in
         Section 1.1 hereof; and in the event any claim is made against the
         Tenant relative to dealings by Landlord with brokers, finders or other
         agents other than the Recognized Broker, if any, designated in Section
         1.1 hereof, Landlord shall defend the claim against Tenant with counsel
         of Landlord's selection and save harmless and indemnify Tenant on
         account of loss, cost or damage which may arise by reason of such
         claim. Landlord agrees that it shall be solely responsible for the
         payment of brokerage commissions to the Recognized Broker for the
         Original Term of this Lease, if any, designated in Section 1.1 hereof.

8.9      INVALIDITY OF PARTICULAR PROVISIONS.
         -----------------------------------

         If any term or provision of this Lease, or the application thereof to
         any person or circumstance shall, to any extent, be invalid or
         unenforceable, the remainder of this Lease, or the application of such
         term or provision to persons or circumstances other than those as to
         which it is held invalid or unenforceable, shall not be affected
         thereby, and each term and provision of this Lease shall be valid and
         be enforced to the fullest extent permitted by law.

8.10     PROVISIONS BINDING, ETC.
         -----------------------

         The obligations of this Lease shall run with the land, and except as
         herein otherwise provided, the terms hereof shall be binding upon and
         shall inure to the benefit of the successors and assigns, respectively,
         of Landlord and Tenant and, if Tenant shall be an


                                      -41-


<Page>


         individual, upon and to his heirs, executors, administrators,
         successors and assigns. Each term and each provision of this Lease to
         be performed by Tenant shall be construed to be both a covenant and a
         condition. The reference contained to successors and assigns of Tenant
         is not intended to constitute a consent to subletting or assignment by
         Tenant.

8.11     RECORDING.
         ---------

         Tenant agrees not to record the within Lease, but each party hereto
         agrees, on the request of the other, to execute a so-called Notice of
         Lease or short form lease in form recordable and complying with
         applicable law and reasonably satisfactory to both Landlord's and
         Tenant's attorneys. In no event shall such document set forth rent or
         other charges payable by Tenant under this Lease; and any such document
         shall expressly state that it is executed pursuant to the provisions
         contained in this Lease, and is not intended to vary the terms and
         conditions of this Lease.

8.12     NOTICES.
         -------

         Whenever, by the terms of this Lease, notice shall or may be given
         either to Landlord or to Tenant, such notice shall be in writing and
         shall be sent by overnight commercial courier or by registered or
         certified mail postage or delivery charges prepaid, as the case may be:

                  If intended for Landlord, addressed to Landlord at the address
                  set forth in Article I of this Lease (or to such other address
                  or addresses as may from time to time hereafter be designated
                  by Landlord by like notice) with a copy to Landlord,
                  Attention: General Counsel.

                  If intended for Tenant, addressed to Tenant at the address set
                  forth in Article I of this Lease except that from and after
                  the Commencement Date the address of Tenant shall be the
                  Premises (or to such other address or addresses as may from
                  time to time hereafter be designated by Tenant by like
                  notice).

         Except as otherwise provided herein, all such notices shall be
         effective when received; provided, that (i) if receipt is refused,
         notice shall be effective upon the first occasion that such receipt is
         refused, (ii) if the notice is unable to be delivered due to a change
         of address of which no notice was given, notice shall be effective upon
         the date such delivery was attempted or (iii) if the notice address is
         a post office box number, notice shall be effective the day after such
         notice is sent as provided hereinabove.

         Where provision is made for the attention of an individual or
         department, the notice shall be effective only if the wrapper in which
         such notice is sent is addressed to the attention of such individual or
         department.

         Any notice given by an attorney on behalf of Landlord or by Landlord's
         managing agent shall be considered as given by Landlord and shall be
         fully effective.


                                      -42-


<Page>


         Time is of the essence with respect to any and all notices and periods
         for giving notice or taking any action thereto under this Lease.

8.13     WHEN LEASE BECOMES BINDING.
         --------------------------

         Employees or agents of Landlord have no authority to make or agree to
         make a lease or any other agreement or undertaking in connection
         herewith. The submission of this document for examination and
         negotiation does not constitute an offer to lease, or a reservation of,
         or option for, the Premises, and this document shall become effective
         and binding only upon the execution and delivery hereof by both
         Landlord and Tenant. All negotiations, considerations, representations
         and understandings between Landlord and Tenant are incorporated herein
         and may be modified or altered only by written agreement between
         Landlord and Tenant, and no act or omission of any employee or agent of
         Landlord shall alter, change or modify any of the provisions hereof.

8.14     SECTION HEADINGS.
         ----------------

         The titles of the Articles throughout this Lease are for convenience
         and reference only, and the words contained therein shall in no way be
         held to explain, modify, amplify or aid in the interpretation,
         construction or meaning of the provisions of this Lease.

8.15     RIGHTS OF MORTGAGEE.
         -------------------

         This Lease shall be subject and subordinate to any mortgage now or
         hereafter on the Site or the Building, or both, and to each advance
         made or hereafter to be made under any mortgage, and to all renewals,
         modifications, consolidations, replacements and extensions thereof and
         all substitutions therefor provided that the holder of such mortgage
         agrees to recognize the rights of Tenant under this Lease (including
         the right to use and occupy the Premises) upon the payment of rent and
         other charges payable by Tenant under this Lease and the performance by
         Tenant of Tenant's obligations hereunder in which event Tenant shall
         agree to attorn to such holder and its successors as landlord. In
         confirmation of such subordination and recognition, Tenant shall
         execute and deliver promptly such instruments of subordination and
         recognition as such mortgagee may reasonably request. Tenant hereby
         appoints such mortgagee (from time to time) as Tenant's
         attorney-in-fact to execute such subordination upon default of Tenant
         in complying with such mortgagee's (from time to time) request. In the
         event that any mortgagee or its respective successor in title shall
         succeed to the interest of Landlord, then, this Lease shall
         nevertheless continue in full force and effect and Tenant shall and
         does hereby agree to attorn to such mortgagee or successor and to
         recognize such mortgagee or successor as its landlord. If any holder of
         a mortgage which includes the Premises, executed and recorded prior to
         the date of this Lease, shall so elect, this Lease and the rights of
         Tenant hereunder, shall be superior in right to the rights of such
         holder, with the same force and effect as if this Lease had been
         executed, delivered and recorded, or a statutory Notice hereof
         recorded, prior to the execution, delivery and recording of any such
         mortgage. The election of any such holder shall become effective upon
         either notice from such holder to Tenant in the same fashion as notices
         from Landlord to Tenant are to be given hereunder or by the recording
         in the appropriate registry or recorder's


                                      -43-


<Page>


         office of an instrument in which such holder subordinates its rights
         under such mortgage to this Lease.

         If in connection with obtaining financing a bank, insurance company,
         pension trust or other institutional lender shall request reasonable
         modifications in this Lease as a condition to such financing, Tenant
         will not unreasonably withhold, delay or condition its consent thereto,
         provided that such modifications do not increase the monetary or other
         obligations of Tenant hereunder or materially adversely affect the
         leasehold interest hereby created, or materially decrease the
         obligations of Landlord hereunder.

8.16     STATUS REPORTS AND FINANCIAL STATEMENTS.
         ---------------------------------------

         Recognizing that Landlord may find it necessary to establish to third
         parties, such as accountants, banks, potential or existing mortgagees,
         potential purchasers or the like, the then current status of
         performance hereunder, Tenant, on the request of Landlord made from
         time to time (but no more often than once during any twelve (12) month
         period), will promptly furnish to Landlord, or any existing or
         potential holder of any mortgage encumbering the Premises, the
         Building, the Site and/or the Complex or any potential purchaser of the
         Premises, the Building, the Site and/or the Complex, (each an
         "Interested Party"), a statement of the status of any matter pertaining
         to this Lease, including, without limitation, acknowledgments that (or
         the extent to which) each party is in compliance with its obligations
         under the terms of this Lease. In addition, Tenant shall deliver to
         Landlord, or any Interested Party designated by Landlord, financial
         statements of Tenant and any guarantor of Tenant's obligations under
         this Lease, as reasonably requested by Landlord, including, but not
         limited to financial statements for the past three (3) years. Any such
         status statement or financial statement delivered by Tenant pursuant to
         this Section 8.16 may be relied upon by any Interested Party.

8.17     SELF-HELP.
         ---------

         If Tenant shall at any time default in the performance of any
         obligation under this Lease, Landlord shall have the right, but shall
         not be obligated, to enter upon the Premises and to perform such
         obligation notwithstanding the fact that no specific provision for such
         substituted performance by Landlord is made in this Lease with respect
         to such default. In performing such obligation, Landlord may make any
         payment of money or perform any other act. All sums so paid by Landlord
         (together with interest at the rate of one and one-half percentage
         points over the then prevailing prime rate in Boston as set by Bank of
         America, N.A., or its successor (but in no event greater than the
         maximum rate permitted by applicable law) and all costs and expenses in
         connection with the performance of any such act by Landlord, shall be
         deemed to be Additional Rent under this Lease and shall be payable to
         Landlord immediately on demand. Landlord may exercise the foregoing
         rights without waiving any other of its rights or releasing Tenant from
         any of its obligations under this Lease.


                                      -44-


<Page>


8.18     HOLDING OVER.
         ------------

         Any holding over by Tenant after the expiration of the term of this
         Lease shall be treated as a tenancy at sufferance and shall be on the
         terms and conditions as set forth in this Lease, as far as applicable
         except that Tenant shall pay as a use and occupancy charge an amount
         equal to the greater of (x) 150% of the Annual Fixed Rent and
         Additional Rent calculated (on a daily basis) at the highest rate
         payable under the terms of this Lease, or (y) the fair market rental
         value of the Premises, in each case for the period measured from the
         day on which Tenant's hold-over commences and terminating on the day on
         which Tenant vacates the Premises. In addition, Tenant shall save
         Landlord, its agents and employees harmless and will exonerate, defend
         and indemnify Landlord, its agents and employees from and against any
         and all damages which Landlord may suffer on account of Tenant's
         hold-over in the Premises after the expiration or prior termination of
         the term of this Lease. Nothing in the foregoing nor any other term or
         provision of this Lease shall be deemed to permit Tenant to retain
         possession of the Premises or hold over in the Premises after the
         expiration or earlier termination of the Lease Term. All property which
         remains in the Building or the Premises after the expiration or
         termination of this Lease shall be conclusively deemed to be abandoned
         and may either be retained by Landlord as its property or sold or
         otherwise disposed of in such manner as Landlord may see fit. If any
         part thereof shall be sold, then Landlord may receive the proceeds of
         such sale and apply the same, at its option against the expenses of the
         sale, the cost of moving and storage, any arrears of rent or other
         charges payable hereunder by Tenant to Landlord and any damages to
         which Landlord may be entitled under this Lease and at law and in
         equity.

8.19     NON-SUBROGATION.
         ---------------

         Any insurance carried by either party with respect to the Premises or
         property therein or occurrences thereon shall, if it can be so written
         without additional premium or with an additional premium which the
         other party agrees to pay, include a clause or endorsement denying to
         the insurer rights of subrogation against the other party to the extent
         rights have been waived by the insured prior to occurrence of injury or
         loss. Each party, notwithstanding any provisions of this Lease to the
         contrary, hereby waives any rights of recovery against the other for
         injury or loss due to hazards covered by such insurance (or which would
         have been covered had such party carried the insurance required to be
         carried by it under the Lease) to the extent of the indemnification
         received under such insurance policy. This waiver of rights by Tenant
         shall apply to, and be for the benefit of, Landlord's managing agent.

8.20     SECURITY DEPOSIT.
         ----------------

         If, in Section 1.1 hereof, a security deposit is specified, Tenant
         agrees that the same will be paid upon execution and delivery of this
         Lease, and that Landlord shall hold the same, throughout the term of
         this Lease (including any extension thereof), as security for the
         performance by Tenant of all obligations on the part of Tenant to be
         kept and performed. Landlord shall have the right from time to time
         without prejudice to any other remedy Landlord may have on account
         thereof, to apply such deposit, or any part thereof, to


                                      -45-


<Page>


         Landlord's damages arising from any default on the part of Tenant. If
         Landlord so applies all or any portion of such deposit, Tenant shall
         within seven (7) days after notice from Landlord deliver cash to
         Landlord in an amount sufficient to restore such deposit to the full
         amount stated in Section 1.1. Tenant not then being in default and
         having performed all of its obligations under this Lease, including
         the payment of all Annual Fixed Rent, Landlord shall return the
         deposit, or so much thereof as shall not have theretofore been applied
         in accordance with the terms of this Section 8.20, to Tenant on the
         expiration or earlier termination of the term of this Lease and
         surrender possession of the Premises by Tenant to Landlord in the
         condition required in the Lease at such time. While Landlord holds
         such deposit, Landlord shall have no obligation to pay interest on the
         same and shall have the right to commingle the same with Landlord's
         other funds. If Landlord conveys Landlord's interest under this Lease,
         the deposit, or any part thereof not previously applied, may be turned
         over by Landlord to Landlord's grantee, and, if so turned over, Tenant
         agrees to look solely to such grantee for proper application of the
         deposit in accordance with the terms of this Section 8.20, and the
         return thereof in accordance herewith.

         Neither the holder of any mortgage nor the lessor in any ground lease
         on property which includes the Premises shall ever be responsible to
         Tenant for the return or application of any such deposit, whether or
         not it succeeds to the position of Landlord hereunder, unless such
         deposit shall have been received in hand by such holder or ground
         lessor.

8.21     LATE PAYMENT.
         ------------

         If Landlord shall not have received any payment or installment of
         Annual Fixed Rent or Additional Rent (the "Outstanding Amount") on or
         before the date on which the same first becomes payable under this
         Lease (the "Due Date"), the amount of such payment or installment shall
         incur a late charge equal to the sum of: (a) five percent (5%) of the
         Outstanding Amount for administration and bookkeeping costs associated
         with the late payment and (b) interest on the Outstanding Amount from
         the Due Date through and including the date such payment or installment
         is received by Landlord, at a rate equal to the lesser of (i) the rate
         announced by Bank of America, N.A., (or its successor) from time to
         time as its prime or base rate (or if such rate is no longer available,
         a comparable rate reasonably selected by Landlord), plus two percent
         (2%), or (ii) the maximum applicable legal rate, if any. Such interest
         shall be deemed Additional Rent and shall be paid by Tenant to Landlord
         upon demand.

         Notwithstanding the foregoing, Landlord agrees that such late charge
         will not be imposed upon the first late payment under this Lease until
         five (5) days after the date on which such payment first became due and
         payable.

8.22     TENANT'S PAYMENTS.
         -----------------

         Each and every payment and expenditure, other than Annual Fixed Rent,
         shall be deemed to be Additional Rent hereunder, whether or not the
         provisions requiring payment of such amounts specifically so state, and
         shall be payable, unless otherwise provided in this Lease, within
         twenty (20) days after written demand by Landlord, and in the case of
         the


                                      -46-


<Page>


         non-payment of any such amount, Landlord shall have, in addition to
         all of its other rights and remedies, all the rights and remedies
         available to Landlord hereunder or by law in the case of non-payment of
         Annual Fixed Rent. Unless expressly otherwise provided in this Lease,
         the performance and observance by Tenant of all the terms, covenants
         and conditions of this Lease to be performed and observed by Tenant
         shall be at Tenant's sole cost and expense. If Tenant has not objected
         to any statement of Additional Rent which is rendered by Landlord to
         Tenant within ninety (90) days after Landlord has rendered the same to
         Tenant, then the same shall be deemed to be a final account between
         Landlord and Tenant not subject to any further dispute. In the event
         that Tenant shall seek Landlord's consent or approval under this Lease,
         then Tenant shall reimburse Landlord, upon demand, as Additional Rent,
         for all reasonable costs and expenses, including legal and
         architectural costs and expenses, incurred by Landlord in processing
         such request, whether or not such consent or approval shall be given.

8.23     WAIVER OF TRIAL BY JURY.
         -----------------------

         To induce Landlord to enter into this Lease, Tenant hereby waives any
         right to trial by jury in any action, proceeding or counterclaim
         brought by either Landlord or Tenant on any matters whatsoever arising
         out of or any way connected with this Lease, the relationship of the
         Landlord and the Tenant, the Tenant's use or occupancy of the Premises
         and/or any claim of injury or damage, including but not limited to, any
         summary process eviction action.

8.24     GOVERNING LAW.
         ----------------

         This Lease shall be governed exclusively by the provisions hereof and
         by the law of the Commonwealth of Massachusetts, as the same may from
         time to time exist.















                                      -47-


<Page>


     EXECUTED as a sealed instrument in two or more counterparts each of which
shall be deemed to be an original.


<Table>
<S>                                                          <C>
WITNESS:                                                     LANDLORD:

    /s/ Illegible                                                   By:   /s/ David C. Provost
-------------------------------------------------------             ----------------------------------------------
                                                                    DAVID C. PROVOST, FOR THE TRUSTEES OF 91
                                                                    HARTWELL AVENUE TRUST PURSUANT TO WRITTEN
                                                                    DELEGATION BUT NOT INDIVIDUALLY

                                                             TENANT:

ATTEST:                                                      SYNTA PHARMACEUTICALS, INC.

By:              /s/ Wendy E. Rieder                         By:           /s/ John A. McCarthy, Jr.
             ------------------------------------------                 ------------------------------------------

Name:                Wendy E. Rieder                         Name:             John A. McCarthy, Jr.
             ------------------------------------------                 ------------------------------------------

Title:          (Secretary or Assistant Secretary)           Title:           (President or Vice President)
             ------------------------------------------                 ------------------------------------------
                                                                                 Hereto duly authorized

                                       By:                                 /s/ Keith Ehrlich
                                                                        ------------------------------------------

                                                             Name:             Keith Ehrlich
                                                                        ------------------------------------------

                                                             Title:     (Treasurer or Assistant Treasurer)
                                                                        ------------------------------------------
                                                                                 Hereto duly authorized

                                                                                                   CORPORATE SEAL
</Table>






                                      -48-


<Page>



                                    EXHIBIT A
                                    ---------

                               DESCRIPTION OF SITE


That certain parcel of land situate in Lexington in the County of Middlesex and
Commonwealth of Massachusetts, described as follows:

SOUTHEASTERLY             by Hartwell Avenue, two hundred thirty-seven and
                          47/100 feet;

SOUTHEASTERLY             by a curving line forming the junction of said
                          Hartwell Avenue and Hartwell Place, as shown on
                          plan hereinafter mentioned, thirty-nine and 27/100
                          feet;

SOUTHWESTERLY             five hundred thirty-two and 23/100 feet, and

SOUTHWESTERLY, SOUTHERLY and SOUTHEASTERLY one hundred ninety and 25/100 feet,
                          by said Hartwell Place;

SOUTHERLY                 by lot 9 on said plan, three hundred seventy-four and
                          57/100 feet;

SOUTHWESTERLY             three hundred sixty-seven and 65/100 feet;

NORTHWESTERLY             thirty-one and 12/100 feet, and

NORTHWESTERLY             again, eight hundred ninety and 63/100 feet, by land
                          now or formerly of The United States of America;

NORTHEASTERLY             by said United States of America land and by land
                          now or formerly of John W. O(`Connor et al, nine
                          hundred thirty-three and 87/100 feet.

         Said parcel is shown as lot 10 on said plan, (Plan No.31330D).

         All of said boundaries are determined by the Court to be located as
shown on a subdivision plan, as approved by the Court, filed in the Land
Registration Office, a copy of which is filed in the Registry of Deeds for the
South Registry District of Middlesex County in Registration Book 835, Page 146,
with Certificate 141096.

         The above described land is subject to and has the benefit of the
ditches as approximately shown on said plan at date of original decree, (May 17,
1963).


                                    Exhibit A
                                   Page 1 of 3


<Page>


     So much of the above described land as is included within the area marked
"Tennessee Gas Transmission Company Easement 30' wide" is subject to the
easements set forth in a taking by the Northeastern Gas Transmission Company,
dated July 13, 1951 and duly recorded in Book 7772, Page 162.

     The above described land is subject to an Avigation Easement set forth in a
Declaration of Taking by the United States of America dated February 12, 1954
recorded with the Middlesex South District Registry of Deeds in Book 8219, Page
421 and more particularly shown as "Avigation Easement A-130E-1" on Plan No.
31330-D (referred to above).

     The above described land is subject to an Order by the Town of Lexington
for construction of water main in Hartwell Avenue, Document No. 461902 as
affected by Certificate for Dissolving Betterments filed as Document No. 499500.

     The above described land is subject to a Grant of Easement from Wilbur C.
Nylander et al Trs. to the Town of Lexington to construct and maintain sewer in
Hartwell Place, Document No. 508567.

     The above described land is subject to a grant of Easement over 20 feet
wide drain easement (i) for the benefit of lot 9 in common with others entitled
thereto, set forth in Document 511666 and (ii) set forth in Document No. 479843
for the benefit of lot 7 shown on plan recorded with said Document No. 479843.

     The above described land is subject to a Taking of easement by the Town of
Lexington in Hartwell Place, Document No. 544200.

     The above described land is subject to and has the benefit of a Grant of
Easement and Reservation from Wilbur C. Nylander et al Trs. to the Town of
Lexington for conservation purposes, Document No. 616453.

     The above described land is subject to and has the benefit of the
following:

     A.   Order of Conditions issued by the Town of Lexington Conservation
          Commission filed as Document No. 616456 as extended by Extension
          Permits issued by said Conservation Commission filed as Document Nos.
          627154, 635069, 655552 and 669180.

     B.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 616457.

     C.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 616458.



                                    Exhibit A
                                   Page 2 of 3


<Page>


     D.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 616459.

     E.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 634489.

     F.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 646344.

     G.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 646345.

     H.   Decision of the Town of Lexington Board of Appeals filed as Document
          No. 646346.

     The above described land is subject to an Easement granted to Boston Edison
Company filed as Document No. 672152.

     The above described land is subject to such other easements, agreements and
matters of record, if any, insofar as in force and applicable.











                                    Exhibit A
                                   Page 3 of 3


<Page>



                                    EXHIBIT C
                                    ---------

                                LANDLORD SERVICES


I.   CLEANING
     --------

     Cleaning and janitorial services shall be provided as needed Monday through
     Friday, exclusive of holidays, Saturdays and Sundays.

     A.   OFFICE AREAS
          ------------

          Cleaning and janitorial services to be provided in the office areas
          shall include:

               1.   Vacuuming, damp mopping of resilient floors and trash
                    removal.

               2.   Dusting of horizontal surfaces within normal reach (tenant
                    equipment to remain in place).

               3.   High dusting and dusting of vertical blinds to be rendered
                    as needed.

     B.   LAVATORIES
          ----------

          Cleaning and janitorial services to be provided in the common area
          lavatories of the building shall include:

               1.   Dusting, damp mopping of resilient floors, trash removal,
                    sanitizing of basins, bowls and urinals as well as cleaning
                    of mirrors and bright work.

               2.   Refilling of soap, towel, tissue and sanitary dispensers to
                    be rendered as necessary.

               3.   High dusting to be rendered as needed.

     C.   MAIN LOBBIES, ELEVATORS, STAIRWELLS AND COMMON CORRIDORS
          --------------------------------------------------------

          Cleaning and janitorial services to be provided in the common areas of
          the building shall include:


                                    Exhibit C
                                   Page 1 of 3


<Page>


               1.   Trash removal, vacuuming, dusting and damp mopping of
                    resilient floors and cleaning and sanitizing of water
                    fountains.

               2.   High dusting to be rendered as needed.

     D.   WINDOW CLEANING
          ---------------

          All exterior windows shall be washed on the inside and outside
          surfaces at frequency necessary to maintain a first class appearance.


II.  HVAC
     ----

     A.   Heating, ventilating and air conditioning equipment will be provided
          with sufficient capacity to accommodate a maximum population density
          of one (1) person per one hundred fifty (150) square feet of useable
          floor area served, and a combined lighting and standard electrical
          load of 3.0 watts per square foot of useable floor area. In the event
          Tenant introduces into the Premises personnel or equipment which
          overloads the system's ability to adequately perform its proper
          functions, Landlord shall so notify Tenant in writing and
          supplementary system(s) may be required and installed by Landlord at
          Tenant's expense, if within fifteen (15) days Tenant has not modified
          its use so as not to cause such overload.

          Operating criteria of the basic system are in accordance with the
          Massachusetts Energy Code and shall not be less than the following:

               (i)  Cooling season indoor conditions of not in excess of 78
                    degrees Fahrenheit when outdoor conditions are 91 degrees
                    Fahrenheit drybulb and 73 degrees Fahrenheit wetbulb.

               (ii) Heating season minimum room temperature of 72 degrees
                    Fahrenheit when outdoor conditions are 6 degrees Fahrenheit
                    drybulb.

     B.   Landlord shall provide heating, ventilating and air conditioning as
          normal seasonal charges may require during the hours of 8:00 a.m. to
          6:00 p.m., Monday through Friday, and 8:00 a.m. to 12:00 p.m. on
          Saturdays (legal holidays in all cases excepted).

          If Tenant shall require air conditioning (during the air conditioning
          season) or heating or ventilating during any other time period,
          Landlord shall use landlord's best efforts to furnish such services
          for the area or areas specified by written request of Tenant delivered
          to the Building Superintendent or the Landlord before 3:00 p.m. of the
          business day


                                    Exhibit C
                                   Page 2 of 3


<Page>


          preceding the extra usage. Landlord shall charge Tenant for such
          extra-hours usage at reasonable rates customary for first-class office
          buildings in the Boston Suburban market, and Tenant shall pay
          Landlord, as additional rent, upon receipt of billing therefor.


III. ELECTRICAL SERVICES
     -------------------

     A.   Landlord shall provide electric power for a combined load of 3.0 watts
          per square foot of useable area for lighting and for office machines
          through standard receptacles for the typical office space.

     B.   In the event that Tenant has special equipment (such as computers and
          reproduction equipment) that requires either 3-phase electric power or
          any voltage other than 120 amps, or for any other usage in excess of
          3.0 watts per square foot, Landlord may at its option require the
          installation of separate metering (Tenant being solely responsible for
          the costs of any such separate meter and the installation thereof) and
          direct billing to Tenant for the electric power required for any such
          special equipment.

     C.   Landlord will furnish and install, at Tenant's expense, all
          replacement lighting tubes, lamps and ballasts required by Tenant.
          Landlord will clean lighting fixtures on a regularly scheduled basis
          at Tenant's expense.


IV.  ELEVATORS
     ---------

     Provide passenger elevator service.


V.   WATER
     -----

     Provide hot water for lavatory purposes and cold water for drinking,
     lavatory and toilet purposes.

VI.  CARD ACCESS SYSTEM
     ------------------

     Landlord will provide a card access system at one entry door of the
     building.



                                    Exhibit C
                                   Page 3 of 3


<Page>



                                    EXHIBIT D
                                    ---------

                                   FLOOR PLAN





























                                    Exhibit D
                                   Page 1 of 1


<Page>



                                    EXHIBIT F
                                    ---------

                              FORMS OF LIEN WAIVERS


              CONTRACTOR'S PARTIAL WAIVER AND SUBORDINATION OF LIEN

STATE OF                                          Date:
       ------------------------------                  -------------------------

                            COUNTY       Application for Payment No.:
---------------------------                                           ----------


OWNER:
                     -----------------------------------------------------------

CONTRACTOR:
                     -----------------------------------------------------------

LENDER / MORTGAGEE:  None
                     -----------------------------------------------------------


1.       Original Contract Amount:        $
                                             -----------------------------------

2.       Approved Change Orders:          $
                                             -----------------------------------

3.       Adjusted Contract Amount:        $
         (line 1 plus line 2)                -----------------------------------

4.       Completed to Date:               $
                                             -----------------------------------

5.       Less Retainage:                  $
                                             -----------------------------------

6.       Total Payable to Date:           $
         (line 4 less line 5)                -----------------------------------

7.       Less Previous Payments:          $
                                             -----------------------------------

8.       Current Amount Due:              $
         (line 6 less line 7)                -----------------------------------

9.       Pending Change Orders:           $
                                             -----------------------------------

10.      Disputed Claims:                 $
                                             -----------------------------------

The undersigned who has a contract with _________________________ for furnishing
labor or materials or both labor and materials or rental equipment, appliances
or tools for the erection, alteration, repair or removal of a building or
structure or other improvement of real property known and identified as located
in ____________ (city or town),


                                    Exhibit F
                                   Page 1 of 7


<Page>


_________County, _________________________ and owned by _________________, upon
receipt of __________ ($__________) in payment of an
invoice/requisition/application for payment dated __________________ does
hereby:

         (a)      waive any and all liens and right of lien on such real
                  property for labor or materials, or both labor and materials,
                  or rental equipment, appliances or tools, performed or
                  furnished through the following date ________________ (payment
                  period), except for retainage, unpaid agreed or pending change
                  orders, and disputed claims as stated above;

         (b)      subordinate any and all liens and right of lien to secure
                  payment for such unpaid, agreed or pending change orders and
                  disputed claims, and such further labor or materials, or both
                  labor and materials, or rental equipment, appliances or tools,
                  except for retainage, performed or furnished at any time
                  through the twenty-fifth day after the end of the above
                  payment period, to the extent of the amount actually advanced
                  by the above lender/mortgagee through such twenty-fifth day.

         Signed under the penalties of perjury this _________ day of _________,
20__.

WITNESS:                                CONTRACTOR:

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

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







                                    Exhibit F
                                   Page 2 of 7


<Page>


                           SUBCONTRACTOR'S LIEN WAIVER

General Contractor:
                     -----------------------------------------------------------

Subcontractor:
                     -----------------------------------------------------------

Owner:
                     -----------------------------------------------------------
Project:
                     -----------------------------------------------------------
Total Amount Previously Paid:                     $
                                                   ----------
Amount Paid This Date:                            $
                                                   ----------
Retainage (Including This Payment) Held to Date:  $
                                                   ----------

In consideration of the receipt of the amount of payment set forth above and any
and all past payments received from the Contractor in connection with the
Project, the undersigned acknowledges and agrees that it has been paid all sums
due for all labor, materials and/or equipment furnished by the undersigned to or
in connection with the Project and the undersigned hereby releases, discharges,
relinquishes and waives any and all claims, suits, liens and rights under any
Notice of Identification, Notice of Contract or statement of account with
respect to the Owner, the Project and/or against the Contractor on account of
any labor, materials and/or equipment furnished through the date hereof.

The undersigned individual represents and warrants that he is the duly
authorized representative of the undersigned, empowered and authorized to
execute and deliver this document on behalf of the undersigned and that this
document binds the undersigned to the extent that the payment referred to herein
is received.

The undersigned represents and warrants that it has paid in full each and every
sub-subcontractor, laborer and labor and/or material supplier with whom
undersigned has dealt in connection with the Project and the undersigned agrees
at its sole cost and expense to defend, indemnify and hold harmless the
Contractor against any claims, demands, suits, disputes, damages, costs,
expenses (including attorneys' fees), liens and/or claims of lien made by such
sub-subcontractors, laborers and labor and/or material suppliers arising out of
or in any way related to the Project. This document is to take effect as a
sealed instrument.





                                    Exhibit F
                                   Page 3 of 7


<Page>



Signed under the penalties of perjury as of this ______
day of ______________, 20__.

SUBCONTRACTOR:                                     Signature and Printed Name of
                                                   Individual
                                                   Signing this Lien Waiver


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


WITNESS:


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

Name:
      ----------------------------------------

Title:
       ---------------------------------------

Dated:
      ----------------------------------------






                                    Exhibit F
                                   Page 4 of 7


<Page>



                 CONTRACTOR'S WAIVER OF CLAIMS AGAINST OWNER AND
                         ACKNOWLEDGMENT OF FINAL PAYMENT


Commonwealth of Massachusetts                    Date:
                                                       -------------------------

COUNTY OF                                 Invoice No.:
          -------------------------------              -------------------------


OWNER:
                ----------------------------------------------------------------

CONTRACTOR:
                ----------------------------------------------------------------
PROJECT:
                ----------------------------------------------------------------


1.       Original Contract Amount:                $
                                                    ---------

2.       Approved Change Orders:                  $
                                                    ---------

3.       Adjusted Contract Amount:                $
                                                    ---------

4.       Sums Paid on Account of Contract Amount: $
                                                    ---------

5.       Less Final Payment Due:                  $
                                                    ---------

The undersigned being duly sworn hereby attests that when the Final Payment
Due as set forth above is paid in full by Owner, such payment shall constitute
payment in full for all labor, materials, equipment and work in place furnished
by the undersigned in connection with the aforesaid contract and that no further
payment is or will be due to the undersigned.

The undersigned hereby attests that it has satisfied all claims against it for
items, including by way of illustration but not by way of limitation, items of:
labor, materials, insurance, taxes, union benefits, equipment, etc. employed in
the prosecution of the work of said contract, and acknowledges that satisfaction
of such claims serves as an inducement for the Owner to release the Final
Payment Due.

The undersigned hereby agrees to indemnify and hold harmless the Owner from and
against all claims arising in connection with its Contract with respect to
claims for the furnishing of labor, materials and equipment by others. Said
indemnification and hold harmless shall include the reimbursement of all actual
attorney's fees and all costs and expenses of every nature, and shall be to the
fullest extent permitted by law.



                                    Exhibit F
                                   Page 5 of 7


<Page>


The undersigned hereby irrevocably waives and releases any and all liens and
right of lien on such real property and other property of the Owner for labor or
materials, or both labor and materials, or rental equipment, appliances or
tools, performed or furnished by the undersigned, and anyone claiming by,
through, or under the undersigned, in connection with the Project.

The undersigned hereby releases, remises and discharges the Owner, any agent of
the Owner and their respective predecessors, successors, assigns, employees,
officers, shareholders, directors, and principals, whether disclosed or
undisclosed (collectively "Releasees") from and against any and all claims,
losses, damages, actions and causes of action (collectively "Claims") which the
undersigned and anyone claiming by, through or under the undersigned has or may
have against the Releasees, including, without limitation, any claims arising in
connection with the Contract and the work performed thereunder.

Notwithstanding anything to the contrary herein, payment to the undersigned of
the Final Payment Due sum as set forth above, shall not constitute a waiver by
the Owner of any of its rights under the contract including by way of
illustration but not by way of limitation guarantees and/or warranties. Payment
will not be made until a signed waiver is returned to Owner.

The undersigned individual represents and warrants that he/she is the duly
authorized representative of the undersigned, empowered and authorized to
execute and deliver this document on behalf of the undersigned.

Signed under the penalties of perjury as a sealed instrument as of this ___ day
of ________________, _____.

                                                                     Corporation
                                  ----------------------------------

                           By:
                                   ---------------------------------------------
                           Name:
                                   ---------------------------------------------
                           Title:
                                   ---------------------------------------------
                                            Hereunto duly authorized









                                    Exhibit F
                                   Page 6 of 7


<Page>


                          COMMONWEALTH OF MASSACHUSETTS

COUNTY OF SUFOLK

         On this ___ day of __________, 20___, before me, the undersigned notary
public, personally appeared _____________________________, proved to me through
satisfactory evidence of identification, to be the person whose name is signed
on the preceding or attached document, and acknowledged to me that he/she signed
it as ______________ for ______________, a corporation/partnership voluntarily
for its stated purpose.


------------------------------------------------
NOTARY PUBLIC
My Commission Expires:









                                    Exhibit F
                                   Page 7 of 7