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                                                                   Exhibit 10.18

                                 LEASE AGREEMENT

     THIS LEASE AGREEMENT is made this 24 day of Feb., 2000, between
ARE-ONE INNOVATION DRIVE, LLC, a Delaware limited liability company
("Landlord"), and t.Breeders, Inc., a Delaware corporation ("Tenant").

Address:    One Innovation Drive, Worcester, Massachusetts

Premises:   That portion of the Project, containing approximately 12,254
            rentable square feet, as determined by Landlord, as shown on Exhibit
            A.

Project:    The real property on which the building in which the Premises are
            located, together with all improvements thereon and appurtenances
            thereto as described on Exhibit B.

<Table>
<S>                                         <C>
Base Rent:  $18,636.30, per month          Rentable Area of Premises: 12,254 sq.ft

Rentable Area of Project:  115,179 sq. ft.  Tenant's Share of Operating
                                            Expenses: 10.64%

Security Deposit:  $161,818.00            Target Commencement Date: February
                                            1, 2000

Rent Adjustment Percentage:                 Greater of 3% or the CPI Adjustment
                                            Percentage, not to exceed 7%.
</Table>

Base Term:  60 months from the first day of the month following the month in
            which the Commencement Date occurs.

Permitted Use:     Research and development laboratory, related office and other
                   related uses.

Address for Rent Payment:                    Landlord's Notice Address:
135 N. Los Robles Avenue, Suite 250          135 N. Los Robles Avenue, Suite 250
Pasadena, CA 91101                           Pasadena, CA 91101
Attention: Accounts Receivable               Attention: General Counsel

Tenant's Notice Address:
t.Breeders, Inc.
One Innovation Drive
Worcester, MA 01605
Attention:    Mr. Morey Kraus

     The following Exhibits and Addenda are attached hereto and incorporated
herein by this reference:

/X/  EXHIBIT A - PREMISES DESCRIPTION    /X/  EXHIBIT B - DESCRIPTION OF PROJECT
/X/  EXHIBIT C - WORK LETTER             /X/  EXHIBIT D - COMMENCEMENT DATE
/X/  EXHIBIT E - RULES AND REGULATIONS   /X/  EXHIBIT F - TENANT'S PERSONAL
                                                          PROPERTY

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/X/  EXHIBIT G - ESTOPPEL CERTIFICATE    /X/  EXHIBIT H - NONDISTURBANCE
                                                          AGREEMENT

     1. LEASE OF PREMISES. Upon and subject to all of the terms and conditions
hereof, Landlord hereby leases the Premises to Tenant and Tenant hereby leases
the Premises from Landlord. The portions of the Project which are for the
non-exclusive use of tenants of the Project are collectively referred to herein
as the "COMMON AREAS." Landlord reserves the right to modify Common Areas,
provided that such modification do not materially adversely affect Tenant's use
of the parking area or Tenant's use of the Premises for the Permitted Use.

     2. DELIVERY; ACCEPTANCE OF PREMISES; COMMENCEMENT DATE. Landlord shall use
reasonable efforts to deliver the Premises to Tenant on or before the Target
Commencement Date ("Delivery" or "Deliver"). if Landlord fails to timely Deliver
the Premises, Landlord shall not be liable to Tenant for any loss or damage
resulting therefrom, and this Lease shall not be void or voidable except as
provided herein. If Landlord does not Deliver the Premises within 60 days of the
Target Commencement Date for any reason other than Force Majeure Delays or the
failure of the existing tenant, Massachusetts Biomedical Institute, Inc.
("MBI"), to vacate the Premises, this Lease shall be voidable by Landlord or
Tenant by written notice to the other, and if so voided by either: (a) so long
as Tenant is not in default hereunder, the Security Deposit shall be returned to
Tenant, and (b} neither Landlord nor Tenant shall have any further rights,
duties or obligations under this Lease, except with respect to provisions which
expressly survive termination of this Lease. If neither Landlord nor Tenant
elects to void this Lease within 5 business days of the lapse of such 60 day
period, such right to void this Lease shall be waived and this Lease shall
remain in full force and effect.

     The "COMMENCEMENT DATE" shall be the date Landlord Delivers the Premises to
Tenant. Upon request of Landlord, Tenant shall execute and deliver a written
acknowledgment of the Commencement Date and the expiration date of the Term when
such are established in the form attached to this Lease as Exhibit D; PROVIDED,
HOWEVER, Tenant's failure to execute and deliver such acknowledgment shall not
affect Landlord's rights hereunder. The "Term" of this Lease shall be the Base
Term and the Extension Term which Tenant may elect pursuant to Section 40
hereof.

     Except as set forth in the Work Letter, if applicable: (i) Tenant shall
accept the Premises in their condition as of the Commencement Date, subject to
all applicable laws, ordinances, regulations, covenants and restrictions; (ii)
Landlord shall have no obligation for any defects in the Premises; and (ii)
Tenant's taking possession of the Premises shall be conclusive evidence that
Tenant accepts the Premises and that the Premises were in good condition at the
time possession was taken. Any occupancy of the Premises by Tenant before the
Commencement Date shall be subject to all of the terms and conditions of this
Lease.

     Tenant acknowledges and agrees that Tenant's use and occupancy of the
Premises may be severely and adversely impacted by Landlord's Work and Tenant
shall not be entitled and waives any claim to any abatement of rent or any other
concession as a result of any such adverse impact.

<PAGE>

     Tenant agrees and acknowledges that neither Landlord nor any agent of
Landlord has made any representation or warranty with respect to the condition
of any or all of the Premises or the Project, and/or the suitability of the
Premises or the Project for the conduct of Tenant's business, and Tenant waives
any implied warranty that the Premises or the Project are suitable for the
Permitted Use. This Lease including all exhibits hereto constitutes the complete
agreement of Landlord and Tenant with respect to the subject matter hereof and
supersedes any and all prior representations, inducements, promises, agreements,
understandings and negotiations which are not contained herein. Landlord in
executing this Lease does so in reliance upon Tenant's representations,
warranties, acknowledgments and agreements contained herein.

     Tenant hereby acknowledges and agrees that the Premises is currently
subject to a lease with MBI ("EXISTING LEASE") and that a portion of the
Premises may be subject to the prior rights of other tenants of the Project.
This Lease and Landlord's obligations hereunder shall be subject to (i) the
release or expiration of any prior rights of any other tenant of the Project
pursuant to such tenant's lease in and to any portion of the Premises, and (ii)
Landlord's receipt of a fully executed termination agreement with respect to the
Existing Lease and the vacation of the Premises by MBI.

     3. Rent.

     (a) BASE RENT. The first month's Base Rent, as adjusted pursuant to Section
4 hereof, and the Security Deposit shall be due and payable on delivery of an
executed copy of this Lease to Landlord. Tenant shall pay to Landlord in
advance, without demand, abatement, deduction or set-off, monthly installments
of Base Rent on or before the first day of each calendar month during the Term
hereof, in lawful money of the United States of America, at the office of
Landlord for payment of Rent set forth above, or to such other person or at such
other place as Landlord may from time designate in writing. Payments of Base
Rent for any fractional calendar month shall be prorated and paid on the basis
of a 30 day month. The obligation of Tenant to pay Base Rent and other sums to
Landlord and the obligations of Landlord under this Lease are independent
obligations. Tenant shall have no right at any time to abate, reduce, or set-off
any Rent due hereunder except for any abatement as may be expressly provided in
this Lease.

     (b) ADDITIONAL RENT. In addition to Base Rent, Tenant agrees to pay to
Landlord as additional rent ("Additional Rent"): (i) Tenant's Share of
"Operating Expenses," and (ii) any and all other amounts Tenant assumes or
agrees to pay under the provisions of this Lease, including, without limitation,
any and all other sums that may become due by reason of any default of Tenant or
failure to comply with the agreements, terms, covenants and conditions of this
Lease to be performed by Tenant, after any applicable notice and cure period.

     4. BASE RENT ADJUSTMENTS.

     (a) ADJUSTMENT FOR TENANT IMPROVEMENTS. Upon Substantial Completion of
Landlord's Work ("RENT INCREASE DATE"), Base Rent shall be increased from
$18,636.30 to $26,969.63. As used herein, the term "FORCE MAJEURE DELAYS,"
"SUBSTANTIAL COMPLETION," and "Landlord's Work" shall have the meaning set forth
for such terms in the Work Letter.

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     (b) ANNUAL ADJUSTMENTS. Base Rent, as increased pursuant to Section 4(a),
shall be increased on each annual anniversary of the first day of the first full
month during the Term of this Lease by multiplying the Base Rent payable
immediately before such adjustment by the Rent Adjustment Percentage and adding
the resulting amount to the Base Rent payable immediately before such
adjustment. Base Rent, as so adjusted, shall thereafter be due as provided
herein. Base Rent adjustments for any fractional calendar month shall be
prorated. "CPI Adjustment Percentage" means a fraction, stated as a percentage,
the numerator of which shall be the Index for the calendar month 3 months before
the month in which the Base Rent adjustment is to be made, and the denominator
of which shall be the Index for the calendar month 3 months before the last Base
Rent adjustment or, if no prior Base Rent adjustment has been made; 3 months
before the first day of the first full month during the Term of this Lease.
Landlord shall give Tenant written notice indicating the Base Rent, as adjusted
pursuant to this Section, and the method of computation, and Tenant shall pay to
Landlord an amount equal to any underpayment of Base Rent by Tenant within
fifteen days of Landlord's notice to Tenant. "Index" means the "Consumer Price
Index-All Urban Consumers-Boston, Massachusetts Metropolitan Area" compiled by
the U.S. Department of Labor, Bureau of Labor Statistics, (1 982-84 = 100). If a
substantial change is made in the Index, the revised Index shall be used,
subject to such adjustments as Landlord may reasonably deem appropriate in order
to make the revised index comparable to the prior Index. If the Bureau of Labor
Statistics ceases to publish the Index, then the successor or most nearly
comparable index, as reasonably determined by Landlord, shall be used, subject
to such adjustments as Landlord may reasonably deem appropriate in order to make
the new index comparable to the Index.

     5. OPERATING EXPENSE PAYMENTS. Landlord shall deliver to Tenant a written
estimate of Operating Expenses for each calendar year during the Term (the
"ANNUAL ESTIMATE"), which may be reasonably revised by Landlord from time to
time during such calendar year. During each month of the Term, on the same date
that Base Rent is due, Tenant shall pay Landlord an amount equal to 1/1 2 of the
annual cost, as reasonably estimated by Landlord from time to time, of Tenant's
Share of Operating Expenses. Payments for any fractional calendar month shall be
prorated.

     The term "OPERATING EXPENSES" means all costs and expenses of any kind or
description whatsoever incurred or accrued by Landlord with respect to the
Project (including Taxes, reasonable reserves consistent with good business
practice for future repairs and replacements, capital repairs and improvements
amortized over the lesser of 7 years and the useful life of such capital items
and the costs of Landlord's third party property manager not to exceed 5% of
Base Rent or, if there is no third party property manager, administration rent
in the amount of 5.0% of Base Rent), excluding only:

     (a)  the original construction costs of the Project and renovation prior to
          the date of the Lease and costs of correcting defects in such original
          construction or renovation;

     (b)  completing, fixturing, improving, renovating, painting, redecorating
          or other work, which Landlord pays for or performs for specific
          tenants within their premises and costs of correcting defects in such
          work;

<PAGE>

     (c)  capital expenditures for expansion of the Project;

     (d)  interest, financing costs and amortization of funds borrowed by
          Landlord, whether secured or unsecured and all payments of base rent
          (but not taxes or operating expenses) under any superior ground lease;

     (e)  depreciation of the Project (except for capital improvements, the cost
          of which are includable in Operating Expenses and amortized as set
          forth above);

     (f)  advertising, legal and space planning expenses and leasing commissions
          and other costs and expenses incurred in procuring tenants for the
          Project, including any leasing office maintained in the Project;

     (g)  salaries, wages, benefits and other compensation paid to officers and
          employees of Landlord who are not assigned in whole or in part to the
          operation, management, maintenance or repair of the Project;

     (h)  costs of utilities outside normal business hours sold--to-tenants of
          the Project;

     (i)  any expenses otherwise includable within Operating Expenses to the
          extent actually reimbursed by persons other than tenants of the
          Project under leases for space in the Project;

     (j)  legal and other expenses incurred in the negotiation or enforcement of
          leases;

     (k)  costs relating to maintaining Landlord's existence, either as a
          corporation, partnership, or other entity;

     (l)  costs (including attorneys' fees and costs of settlement, judgments
          and payments in lieu thereof) arising from claims, disputes or
          potential disputes pertaining to Landlord, but not the Project, or
          from Landlord's failure to make any payment required to be made by
          Landlord hereunder before delinquency;

     (m)  costs incurred by Landlord due to the violation by Landlord, its
          employees, agents or contractors or any tenant of the terms and
          conditions of any lease of space in the Project or any Legal
          Requirement;

     (n)  tax penalties incurred as a result of Landlord's negligence, inability
          or unwillingness to make payment and/or to file any tax or
          informational returns when due;

     (o)  overhead and profit increment paid to the Landlord or to subsidiaries
          or affiliates of Landlord for goods and/or services in or to the
          Project to the extent the same exceeds the costs of such goods and/or
          services rendered by unaffiliated third parties on a competitive
          basis;

     (p)  costs arising from Landlord's charitable or political contributions or
          fine art maintained at the Project;

<PAGE>

     (q)  costs to be reimbursed by other tenants of the Project, whether or not
          actually paid;

     (r)  costs in connection with services (including electricity), items or
          other benefits of a type which are not standard for the Project and
          which are not available to Tenant without specific charges therefor,
          but which are provided to another tenant or occupant of the Project,
          whether or not such other tenant or occupant is specifically charged
          therefore by Landlord;

     (s)  costs incurred in the sale or refinancing of the Project; and

     (t)  net income, franchise, capital stock, estate or inheritance taxes.

     Within 90 days after the end of each calendar year, Landlord shall furnish
to Tenant a statement (an "ANNUAL STATEMENT") showing in reasonable detail: (a)
the total and Tenant's Share of actual Operating Expenses for the previous
calendar year, and (b) the total of Tenant's payments in respect of Operating
Expenses for such year. If Tenant's Share of actual Operating Expenses for such
year exceeds Tenant's payments of Operating Expenses for such year, the excess
shall be immediately due and payable by Tenant as Rent. If Tenant's payments of
Operating Expenses for such year exceed Tenant's Share of actual Operating
Expenses for such year Landlord shall, in its sole and absolute discretion,
either: (i) credit the excess amount to the next succeeding installments of
Operating Expenses due hereunder, or (ii) pay the excess to Tenant within 30
days after delivery of such Annual Statement, except that after expiration, or
earlier termination of the Term, Landlord shall pay the excess to Tenant after
deducting all other amounts due Landlord.

     The Annual Statement shall be final and binding upon Tenant unless Tenant,
within 30 days after Tenant's receipt thereof, shall contest any item therein by
giving written notice to Landlord, specifying each item contested and the reason
therefor. If, during such 30 day period, Tenant reasonably and in good faith
questions or contests the correctness of Landlord's statement of Tenant's Share
of Operating Expenses, Landlord will provide Tenant with access to Landlord's
books and records relating to the operation of the Project and such information
as Landlord reasonably determines to be responsive to Tenant's questions. If
after Tenant's review of such information, Landlord and Tenant cannot agree upon
the amount of Tenant's Share of Operating Expenses, then Tenant shall have the
right to have an independent public accounting firm acceptable to Landlord in
its sole and absolute discretion, hired by Tenant (at Tenant's sole cost and
expense) and approved by Landlord (which approval shall not be unreasonably
withheld or delayed), audit and/or review Landlord's books and records relating
to the operation of the Project and such other information relating to the
operation of the Project for the year in question (the "INDEPENDENT REVIEW").
The results of any such Independent Review shall be binding on Landlord and
Tenant. If the Independent Review shows that Tenant's pro rata share of the
Operating Expenses actually paid by Tenant for the calendar year in question
exceeded Tenant's obligations for such calendar year, Landlord shall at
Landlord's option either (i) credit the excess amount to the next succeeding
installments of estimated Operating Expenses or (ii) pay the excess to Tenant
within 30 days after delivery of such statement, except that after expiration or
earlier termination of the Term, Landlord shall pay the excess to Tenant after
deducting all other amounts due Landlord. If the Independent Review shows that
Tenant's payments of Tenant's

<PAGE>

Share of Operating Expenses for such calendar year were less than Tenant's
obligation for the calendar year, Tenant shall pay the deficiency to the
Landlord within 30 days after delivery of such statement. If the Independent
Review shows that Tenant has overpaid Tenant's pro rata share of Operating
Expenses by more than 5% then Landlord shall reimburse Tenant for all costs
incurred by Tenant for the Independent Review. Operating Expenses for the
calendar years in which Tenant's obligation to share therein begins and ends
shall be prorated. Not withstanding anything set forth herein to the contrary,
if the Project is not at least 95% occupied on average during any year of the
Term, Tenant's Share of Operating Expenses for such year shall be computed as
though the Project had been 95% occupied on average during such year.

     "TENANT'S SHARE" shall be the percentage set forth on the first page of
this Lease as Tenant's Share as reasonably adjusted by Landlord for changes in
the physical size of the Premises or the Project occurring thereafter. Landlord
may equitably increase Tenant's Share for any item of expense or cost
reimbursable by Tenant that relates to a repair, replacement, or service that
benefits only the Premises or only a portion of the Project that includes the
Premises or that varies with occupancy or use. Base Rent, Tenant's Share of
Operating Expenses and all other amounts payable by Tenant to Landlord hereunder
are collectively referred to herein as "RENT."

     6. SECURITY DEPOSIT. Tenant shall deposit with Landlord on the date
of this Lease security (the "SECURITY DEPOSIT") for the performance of all of
its obligations in the amount set forth in the Basic Lease Provisions, which
security shall be in the form of either cash or an unconditional and irrevocable
letter of credit (the "LETTER OF CREDIT"): (i) in form and substance
satisfactory to Landlord, (ii) naming Landlord as beneficiary, (iii) expressly
allowing Landlord to draw upon it at any time from time to time by delivering to
the issuer written notice that Landlord is entitled to draw thereunder, (iv)
drawable on an FDIC-insured financial institution satisfactory to Landlord, and
(v) redeemable in the state of Landlord's choice. If Tenant does not provide
Landlord with a substitute Letter of Credit complying with all of the
requirements hereof at least ten (10) days before the stated expiration date of
the then current Letter of Credit, Landlord shall have the right to draw upon
the current Letter of Credit and hold the funds drawn as the Security Deposit.
The Security Deposit shall be held by Landlord as security for the performance
of Tenant's obligations under this Lease. Upon each occurrence of a Default,
Landlord may use all or any part of the Security Deposit to pay delinquent
payments due under this Lease, and the cost of any damage, injury, expense or
liability caused by such Default, without prejudice to any other remedy provided
herein or provided by law. Tenant hereby waives the provisions of any law, now
or hereafter in force, which provide that Landlord may claim from a security
deposit only those sums reasonably necessary to remedy defaults in the payment
of Rent, to repair damage caused by Tenant or to clean the Premises, it being
agreed that Landlord may, in addition, claim those sums reasonably necessary to
compensate Landlord for any other loss or damage, foreseeable or unforeseeable,
caused by the act or omission of Tenant or any officer, employee, agent or
invitee of Tenant. Upon bankruptcy or other debtor-creditor proceedings against
Tenant, the Security Deposit shall be deemed to be applied first to the payment
of Rent and other charges due Landlord for periods prior to the filing of such
proceedings. Upon any such use of all or any portion of the Security Deposit,
Tenant shall, within five (5) days after demand from Landlord, reinstate the
Security Deposit to its original amount. If Tenant shall fully perform every
provision of this Lease to be performed by Tenant, the Security Deposit, or any
balance thereof, shall be returned to Tenant (or, at Landlord's

<PAGE>

option, to the last assignee of Tenant's interest hereunder) within 90 days
after the expiration or earlier termination of this Lease.

     If Landlord transfers its interest in the Project or this Lease, Landlord
shall either (a) upon written notice to Tenant (but without Tenant's consent),
transfer any Security Deposit then held by Landlord to a person or entity
assuming Landlord's obligations under this Section 6, or (b) return to Tenant
any Security Deposit then held by Landlord and remaining after the deductions
permitted herein. Upon such transfer to such transferee and the delivery of
notice to Tenant regarding such transfer or the return of the Security Deposit
to Tenant, Landlord shall have no further obligation with respect to the
Security Deposit, and Tenant's right to the return of the Security Deposit shall
apply solely against Landlord's transferee. The Security Deposit is not an
advance rental deposit or a measure of Landlord's damages in case of Tenant's
default. Landlord's obligation respecting the Security Deposit is that of a
debtor, not a trustee and no interest shall accrue thereon.

     7. USE. The Premises shall be used solely for the Permitted Use set
forth in the Basic Lease Provisions, in compliance with all laws, orders,
judgments, ordinances, regulations, codes, directives, permits, licenses,
covenants and restrictions now or hereafter applicable to the Premises, and the
use and occupancy thereof (collectively, "LEGAL REQUIREMENTS"). Tenant shall,
upon 5 days' written notice from Landlord, discontinue any use of the Premises
which is declared by any governmental authority having jurisdiction to be a
violation of any Legal Requirement. Tenant will not use or permit the Premises
to be used for any purpose or in any manner that would void Tenant's or
Landlord's insurance, increase the insurance risk, or cause the disallowance of
any sprinkler or other credits. Tenant shall reimburse Landlord promptly upon
demand for any additional premium charged for any such insurance policy by
reason of Tenant's failure to comply with the provisions of this Section or
otherwise caused by Tenant's use and/or occupancy of the Premises. Tenant will
use the Premises in a careful, safe and proper manner and will not commit waste,
overload the floor or structure of the Premises, subject the Premises to use
that would damage the Premises or obstruct or interfere with the rights of
Landlord or other tenants or occupants of the Project, including conducting or
giving notice of any auction, liquidation, or going out of business sale on the
Premises, or using or allowing the Premises to be used for any unlawful purpose.
Tenant shall cause any equipment or machinery to be installed in the Premises so
as to reasonably prevent sounds or vibrations therefrom from extending into
Common Areas, or other space in the Project. Tenant shall not place any
machinery or equipment weighing 500 pounds or more in or upon the Premises or
transport or move such items through the Common Areas of the Project or in the
Project elevators without the prior written consent of Landlord. Except as may
be provided under the Work Letter, Tenant shall not, without the prior written
consent of Landlord, use the Premises in any manner which will require
ventilation, air exchange, heating, gas, steam, electricity or water beyond the
existing capacity of the Project as proportionately allocated to the Premises
based upon Tenant's Share as usually furnished for the Permitted Use.

     Tenant, at its sole expense, shall make any alterations or modifications,
to the interior or the exterior of the Premises or the Project, that are
required by Legal Requirements (including, without limitation, compliance of the
Premises with the Americans With Disabilities Act, 42 U.S.C. Section 12101, et
seq. (together with regulations promulgated pursuant thereto, "ADA")) related to
Tenant's use or occupancy of the Premises. Landlord, as part of Operating
Expenses,

<PAGE>

shall be responsible for compliance of the Project (other than the Premises)
with ADA. Landlord shall not be responsible for ADA compliance of the Project to
the extent such compliance is related to or required by Tenant's use or
occupancy of the Premises. Notwithstanding any other provision herein to the
contrary, Tenant shall be responsible for any and all demands, claims,
liabilities, losses, costs, expenses, actions, causes of action, damages or
judgments, and all reasonable expenses incurred in investigating or resisting
the same (including, without limitation, reasonable attorneys' fees, charges and
disbursements and costs of suit) (collectively, "CLAIMS") arising out of or in
connection with Legal Requirements and Tenant shall indemnify, defend, hold and
save Landlord harmless from and against any and all Claims arising out of or in
connection with any failure of the Premises to comply with any Legal
Requirement.

     8. HOLDING OVER. If, with Landlord's express written consent, Tenant
retains possession of the Premises after the termination of the Term, (i) unless
otherwise agreed in such written consent, such possession shall be subject to
immediate termination by Landlord at any time, (ii) all of the other terms and
provisions of this Lease (including, without limitation, the adjustment of Base
Rent pursuant to Section 4 hereof) shall remain in full force and effect
(excluding any expansion or renewal option or other similar right or option)
during such holdover period, (iii) Tenant shall continue to pay Base Rent in the
amount payable upon the date of the expiration or earlier termination of this
Lease or such other amount as Landlord may indicate, in Landlord's sole and
absolute discretion, in such written consent, and (iv) all other payments shall
continue under the terms of this Lease. If Tenant remains in possession of the
Premises after the expiration or earlier termination of the Term without the
express written consent of Landlord, (A) Tenant shall become a tenant at
sufferance upon the terms of this Lease except that the monthly rental shall be
equal to 200% of the Rent in effect during the last 30 days of the Term, and (B)
Tenant shall be responsible for all damages suffered by Landlord resulting from
or occasioned by Tenant's holding over. No holding over by Tenant, whether with
or without consent of Landlord, shall operate to extend this Lease except as
otherwise expressly provided, and this Section 8 shall not be construed as
consent for Tenant to retain possession of the Premises. Acceptance by Landlord
of Rent after the expiration or earlier termination of the Term shall not result
in a renewal or reinstatement of this Lease.

     9. TAXES. Landlord shall pay, as part of Operating Expenses, all taxes,
levies, assessments and governmental charges of any kind (collectively referred
to as "TAXES") imposed by any federal, state, regional, municipal, local or
other governmental authority or agency, including, without limitation,
quasi-public agencies (collectively, "GOVERNMENTAL AUTHORITY") during the Term,
including, without limitation all Taxes: (i) imposed on or measured by or based,
in whole or in part, on rent payable to Landlord under this Lease and/or from
the rental by Landlord of the Project or any portion thereof, or (ii) based on
the square footage assessed value or other measure or evaluation of any kind of
the Premises or the Project, or (iii) assessed or imposed by or on the operation
or maintenance of any portion of the Premises or the Project, including parking,
or (iv) assessed or imposed by, or at the direction of, or resulting from
statutes or regulations, or interpretations thereof, promulgated by, any
Governmental Authority, or (v) imposed as a license or other fee on Landlord's
business of leasing space in the Project. Landlord may contest by appropriate
legal proceedings the amount, validity, or application of any Taxes or liens
securing Taxes. Taxes shall not include any net income taxes imposed on Landlord
unless such net income taxes are in substitution for any Taxes payable
hereunder. If any such Tax is levied or assessed directly against Tenant, then
Tenant shall be responsible for

<PAGE>

and shall pay the same at such times and in such manner as the taxing authority
shall require. Tenant shall pay, prior to delinquency, any and all Taxes levied
or assessed against any personal property or trade fixtures placed by Tenant in
the Premises, whether levied or assessed against Landlord or Tenant. If any
Taxes on Tenant's personal property or trade fixtures are levied against
Landlord or Landlord's property, or if the assessed valuation of the Project is
increased by a value attributable to improvements in or alterations to the
Premises, whether owned by Landlord or Tenant and whether or not affixed to the
real property so as to become a part thereof, higher than the base valuation on
which Landlord from time-to-time allocates Taxes to all tenants in the Project,
Landlord shall have the right, but not the obligation, to pay such Taxes. Upon
written request from Tenant, Landlord shall provide Tenant with written
information evidencing the matters described in the preceding sentence.
Landlord's determination of any excess assessed valuation shall be binding and
conclusive, absent manifest error. The amount of any such payment by Landlord
shall constitute Additional Rent due from Tenant to Landlord immediately upon
demand.

     10. PARKING. Tenant shall have the right to mark 2 two spaces, designated
by Landlord and in a manner acceptable to Landlord, for reserved parking by
Tenant and to park in common with other tenants of the Project in those areas
designated for non-reserved parking subject in each case to Landlord's rules and
regulations. Landlord may allocate parking spaces among Tenant and other tenants
in the Project if Landlord determines that such parking facilities are becoming
crowded. Landlord shall not be responsible and shall have no obligation for
enforcing Tenant's parking rights (including, without limitation, the reserved
parking rights) against any third parties, including other tenants of the
Project.

     11. UTILITIES, SERVICES.

         Landlord shall provide, subject to the terms of this Section 11, water,
electricity, heat, light, power, telephone, sewer, and other utilities
(including gas and fire sprinklers to the extent the Project is plumbed for such
services), refuse and trash collection and janitorial services (collectively,
"UTILITIES") Landlord shall pay, as Operating Expenses or subject to Tenant's
reimbursement obligation, for all Utilities used on the Premises, all
maintenance charges for Utilities, and any storm sewer charges or other similar
charges for Utilities imposed by any governmental entity or Utility provider,
and any taxes, penalties, surcharges or similar charges thereon. Landlord may
cause, at Tenant's expense, any Utilities to be separately metered or charged
directly to Tenant by the provider. Tenant shall pay directly to the Utility
provider, prior to delinquency, any separately metered Utilities and services
which may be furnished to Tenant or the Premises during the Term. Tenant shall
pay, as part of Operating Expenses, its share of all charges for jointly metered
Utilities based upon consumption, as reasonably determined by Landlord. No
interruption or failure of Utilities, from any cause whatsoever other than
Landlord's willful misconduct, shall result in eviction or constructive eviction
of Tenant, termination of this Lease or the abatement of Rent. Tenant agrees to
limit use of water and sewer with respect to Common Areas to normal restroom
use.

     12. ALTERATIONS AND TENANT'S PROPERTY. Any alterations, additions, or
improvements made to the Premises by or on behalf of Tenant, including
additional locks or bolts of any kind or nature upon any doors or windows in the
Premises, but excluding, after prior written notice to Landlord, interior
non-structural alterations costing less than $15,000 and

<PAGE>

installation, removal or realignment of furniture systems (other than removal of
furniture systems owned or paid for by Landlord) not involving any modifications
to the structure or connections (other then by ordinary plugs or jacks) to
building systems (as hereinafter defined) ("Alterations") shall be subject to
Landlord's prior written consent, which may be given or withheld in Landlord's
sole discretion if any such Alteration affects the structure or building
systems. If Landlord approves any Alterations, Landlord may impose such
conditions on Tenant in connection with the commencement, performance and
completion of such Alterations as Landlord may deem appropriate in Landlord's
reasonable discretion. Any request for approval shall be in writing, delivered
not less than 15 business days in advance of any proposed construction, and
accompanied by plans, specifications, bid proposals, work contracts and such
other information concerning the nature and cost of the alterations as may be
reasonably requested by Landlord, including the identities and mailing addresses
of all persons performing work or supplying materials. Landlord's right to
review plans and specifications and to monitor construction shall be solely for
its own benefit, and Landlord shall have no duty to ensure that such plans and
specifications or construction comply with applicable Legal Requirements. Tenant
shall cause, at its sole cost and expense, all Alterations to comply with
insurance requirements and with Legal Requirements and shall implement at its
sole cost and expense any alteration or modification required by Legal
Requirements as a result of any Alterations. Tenant shall pay to Landlord, as
Additional Rent, on demand an amount equal to 3% of all charges incurred by
Tenant or its contractors or agents in connection with any Alteration to cover
Landlord's overhead and expenses for plan review, coordination, scheduling and
supervision. Before Tenant begins any Alteration, Landlord may post on and about
the Premises notices of non-responsibility pursuant to applicable law. Tenant
shall reimburse Landlord for, and indemnify and hold Landlord harmless from, any
expense incurred by Landlord by reason of faulty work done by Tenant or its
contractors, delays caused by such work, or inadequate cleanup.

     Tenant shall furnish security or make other arrangements reasonably
satisfactory to Landlord to assure payment for the completion of all Alteration
work free and clear of liens, and shall provide certificates of insurance for
worker's compensation in statutory amounts and other coverage in amounts and
from an insurance company satisfactory to Landlord protecting Landlord against
liability for personal injury or property damage during construction. Upon
completion of any Alterations, Tenant shall deliver to Landlord: (i) sworn
statements setting forth the names of all contractors and subcontractors who did
the work and final lien waivers from all such contractors and subcontractors;
and (ii) as built plans for any such Alteration.

     Other than (i) the items, if any, listed on EXHIBIT F attached hereto and,
(ii) any items agreed by Landlord in writing to be included on EXHIBIT F in the
future, and (iii) any trade fixtures, machinery, equipment and other personal
property not paid for out of the TI Fund (as defined in the Work Letter) which
may be removed without material damage to the Premises, which damage shall be
repaired by Tenant during the Term (collectively, "TENANT'S PROPERTY"), all
property of any kind paid for with the TI Fund, all Alterations, real property
fixtures, built-in machinery and equipment, built-in casework and cabinets and
other similar additions and improvements built into the Premises so as to become
an integral part of the Premises such as fume hoods which penetrate the roof or
plenum area, built-in cold rooms, built-in warm rooms, walk-in cold rooms,
walk-in warm rooms, deionized water system, chillers, built-in plumbing,
electrical and mechanical equipment and systems, and any power generator and
transfer switch

<PAGE>

(collectively, "INSTALLATIONS") shall be and shall remain the property of
Landlord during the Term and following the expiration or earlier termination of
the Term, shall not be removed by Tenant at any time during the Term and shall
remain upon and be surrendered with the Premises as a part thereof following the
expiration or earlier termination of this Lease; PROVIDED, HOWEVER, that
Landlord shall, at the time its approval of such Installation is requested
notify Tenant if it has elected to cause Tenant to remove such Installation upon
the expiration or earlier termination of this Lease. If Landlord so elects,
Tenant shall remove such Installation upon the expiration or earlier termination
of this Lease and restore any damage caused by or occasioned as a result of such
removal, including, when removing any of Tenant's Property which was plumbed,
wired or otherwise connected to any of the building systems, capping off all
such connections behind the walls of the Premises and repairing any holes.
During any such restoration period, Tenant shall pay Rent to Landlord as
provided herein as if said space were otherwise occupied by Tenant.

     13. LANDLORD'S REPAIRS. Landlord, as an Operating Expense, shall maintain
all of the structural, exterior, parking and other Common Areas of the Project,
including HVAC, plumbing, fire sprinklers, elevators and all other building
systems serving the Premises and other portions of the Project ("BUILDING
SYSTEMS"), in good repair, reasonable wear and tear and uninsured losses and
damages caused by Tenant, its agents, servants, employees, invitees and
contractors excluded. Losses and damages caused by Tenant, its agents, servants,
employees, invitees and contractors shall be repaired by Landlord, to the extent
not covered by insurance, at Tenant's sole cost and expense. Landlord reserves
the right to stop Building System services when necessary (i) by reason of
accident or emergency, or (ii) for planned repairs, alterations or improvements,
which are, in the judgment of Landlord, desirable or necessary to be made, until
said repairs, alterations or improvements shall have been completed. Landlord
shall have no responsibility or liability for failure to supply Building System
services during any such period of interruption; PROVIDED, HOWEVER, that
Landlord shall give Tenant 24 hours advance notice of any planned stoppage of
Building System services for routine maintenance, repairs, alterations or
improvements. Tenant shall promptly give Landlord written notice of any repair
required by Landlord pursuant to this Section, after which Landlord shall have a
reasonable opportunity to effect such repair. Landlord shall not be liable for
any failure to make any repairs or to perform any maintenance unless such
failure shall persist for an unreasonable time after Tenant's written notice of
the need for such repairs or maintenance. Tenant waives it rights under any
state or local law to terminate this Lease or to make such repairs at Landlord's
expense and agrees that the parties' respective rights with respect to such
matters shall be solely as set forth herein. Repairs required as the result of
fire, earthquake, flood, vandalism, war, or similar cause of damage or
destruction shall be controlled by Section 18.

     14. TENANT'S REPAIRS. Subject to Section 13 hereof, Tenant, at its
expense, shall repair, replace and maintain in good condition all portions of
the Premises, including, without limitation, entries, doors, ceilings, interior
windows, interior walls, and the interior side of demising walls. Such repair
and replacements may include capital expenditures and repairs whose benefit may
extend beyond the Term. Should Tenant fail to make any such repair or
replacement or fail to maintain the Premises, Landlord shall give Tenant notice
of such failure. If Tenant fails to commence cure of such default within 10 days
of Landlord's notice, and thereafter diligently prosecute such cure to
completion, Landlord may perform such work and shall be reimbursed by Tenant
within 10 days after demand therefor; provided, however, that if such default by
Tenant creates or could create an emergency, Landlord may immediately

<PAGE>

commence cure of such default and shall thereafter be entitled to recover the
costs of such cure from Tenant. Subject to Sections 1 7 and 18, Tenant shall
bear the full uninsured cost of any repair or replacement to any part of the
Project that results from damage caused by Tenant, its agents, contractors, or
invitees and any repair that benefits only the Premises.

     15. MECHANIC'S LIENS. Tenant shall discharge, by bond or otherwise, any
mechanic's lien filed against the Premises or against the Project for work
claimed to have been done for, or materials claimed to have been furnished to,
Tenant within 15 days after the filing thereof, at Tenant's sole cost and shall
otherwise keep the Premises and the Project free from any liens arising out of
work performed, materials furnished or obligations incurred by Tenant. Should
Tenant fail to discharge any lien described herein, Landlord shall have the
right, but not the obligation, to pay such claim or post a bond or otherwise
provide security to eliminate the lien as a claim against title to the Project
and the cost thereof shall be immediately due from Tenant as Additional Rent. If
Tenant shall lease or finance the acquisition of office equipment, furnishings,
or other personal property of a removable nature utilized by Tenant in the
operation of Tenant's business, Tenant warrants that any Uniform Commercial Code
Financing Statement executed by Tenant will upon its face or by exhibit thereto
indicate that such Financing Statement is applicable only to removable personal
property of Tenant located within the Premises. In no event shall the address of
the Project be furnished on the statement without qualifying language as to
applicability of the lien only to removable personal property, located in an
identified suite held by Tenant.

     16. INDEMNIFICATION. Tenant hereby indemnifies and agrees to defend, save
and hold Landlord harmless from and against any and all Claims for injury or
death to persons or damage to property occurring within or about the Premises,
arising directly or indirectly out of Tenant's use or occupancy of the Premises
or a breach or default by Tenant in the performance of any of its obligations
hereunder, unless caused solely by the willful misconduct or gross negligence of
Landlord or its agents or contractors (to the extent such agents or contractors
are acting within the scope of the their authority). Landlord shall not be
liable to Tenant for, and Tenant assumes all risk of damage to, personal
property (including, without limitation, loss of records kept within the
Premises). Tenant further waives any and all Claims for injury to Tenant's
business or loss of income relating to any such damage or destruction of
personal property (including, without limitation, any loss of records). Landlord
shall not be liable for any damages arising from any act, omission or neglect of
any tenant in the Project or of any other third party.

     17. INSURANCE. Landlord shall maintain all insurance against any peril
generally included within the classification "Fire and Extended Coverage,"
sprinkler damage (if applicable), vandalism and malicious mischief covering the
full replacement cost of the Project or such lesser coverage amount as Landlord
may elect PROVIDED such coverage amount is not less than 90% of such full
replacement cost. Landlord shall further carry commercial general liability
insurance with a single loss limit of not less than $2,000,000 for death or
bodily injury, or property damage with respect to the Project. Landlord may, but
is not obligated to, maintain such other insurance and additional coverages as
it may deem necessary, including, but not limited to, flood, environmental
hazard and earthquake, loss or failure of building equipment, errors and
omissions, rental loss during the period of repair or rebuilding, workmen's
compensation insurance and fidelity-bonds for employees employed to perform
services and insurance for any improvements installed by Tenant or which are in
addition to the standard

<PAGE>

improvements customarily furnished by Landlord without regard to whether or not
such are made a part of the Project. All such insurance shall be included as
part of the Operating Expenses. The Project may be included in a blanket policy
(in which case the cost of such insurance allocable to the Project will be
determined by Landlord based upon the insurer's cost calculations). Tenant shall
also reimburse Landlord for any increased premiums or additional insurance which
Landlord reasonably deems necessary as a result of Tenant's use of the Premises.

     Tenant, at its sole cost and expense, shall maintain during the Term: all
risk property insurance covering the full replacement cost of all property and
improvements installed or placed in the Premises by Tenant at Tenant's expense
(excluding items paid for out of the TI Fund); worker's compensation insurance
with no less than the minimum limits required by law; employer's liability
insurance with such limits as required by law; and commercial general liability
insurance, with a minimum limit of not less than $2,000,000 per occurrence for
death or bodily injury and not less than $1,000,000 for property damage with
respect to the Premises. The commercial general liability insurance policies
shall name Landlord, its officers, directors, employees, managers, agents,
invitees and contractors (collectively, "Related Parties"), as additional
insureds; insure on an occurrence and not a claims-made basis; be issued by
insurance companies which have a rating of not less than policyholder rating of
A and financial category rating of at least Class XII in "Best's Insurance
Guide"; shall not be cancelable unless 30 days prior written notice shall have
been given to Landlord from the insurer; contain a hostile fire endorsement and
a contractual liability endorsement; and provide primary coverage to Landlord
(any policy issued to Landlord providing duplicate or similar coverage shall be
deemed excess over Tenant's policies). Such policies or certificates thereof
shall be delivered to Landlord by Tenant upon commencement of the Term and upon
each renewal of said insurance. Tenant's policy may be a "blanket policy" which
specifically provides that the amount of insurance shall not be prejudiced by
other losses covered by the policy. Tenant shall, at least 20 days prior to the
expiration of such policies, furnish Landlord with renewals or binders. Tenant
agrees that if Tenant does not take out and maintain such insurance, Landlord
may (but shall not be required to) procure said insurance on Tenant's behalf and
at its cost to be paid as Additional Rent.

     In each instance where insurance is to name Landlord as additional insured,
Tenant shall upon written request of Landlord also designate and furnish
certificates so evidencing Landlord as additional insured to: (i) any lender of
Landlord holding a security interest in the Project or any portion thereof, (ii)
the landlord under any lease wherein Landlord is tenant of the real property on
which the Project is located, if the interest of Landlord is or shall become
that of a tenant under a ground lease rather than that of a fee owner, and/or
(iii) any management company retained by Landlord to manage the Project.

     The property insurance obtained by Landlord and Tenant shall include a
waiver of subrogation by the insurers and all rights based upon an assignment
from its insured, against Landlord or Tenant, and their respective Related
Parties, in connection with any loss or damage thereby insured against. Neither
party nor its respective Related Parties shall be liable to the other for loss
or damage caused by any risk insured against under property insurance required
to be maintained hereunder, and each party waives any claims against the other
party, and its respective Related Parties for such loss or damage. The failure
of a party to insure its property shall not void this waiver. Landlord and its
respective Related Parties shall not be liable for, and

<PAGE>

Tenant hereby waives all claims against such parties for, business interruption
and losses occasioned thereby sustained by Tenant or any person claiming through
Tenant resulting from any accident or occurrence in or upon the Premises or the
Project from any cause whatsoever. If the foregoing waivers shall contravene any
law with respect to exculpatory agreements, the liability of Landlord or Tenant
shall be deemed not released but shall be secondary to the other's insurer.

     Landlord may require insurance policy limits to be raised to conform with
requirements of Landlord's lender and to bring coverage limits to levels
standard for the Permitted Use in this type of building in Worcester,
Massachusetts.

     18. RESTORATION. If at any time during the Term the Project or the Premises
are damaged by a fire or other insured casualty, Landlord shall notify Tenant
("Landlord's Notice") within 30 days after discovery of such damage as to the
amount of time Landlord reasonably estimates it will take to restore the Project
or the Premises, as applicable. If the restoration time is estimated to exceed
12 months, Landlord may, in such notice, elect to terminate this Lease as of the
date that is 45 days after the date of discovery of such damage or destruction.
If Landlord's Notice states that the restoration time is estimated to exceed 12
months, Tenant shall have the right to elect to terminate this Lease as of the
date that is 10 days after Landlord's Notice; provided, however, that Tenant's
right to terminate shall expire if not exercised within 5 days after Landlord's
Notice. Unless Landlord or Tenant elects to terminate this Lease, Landlord
shall, subject to receipt of sufficient insurance proceeds (with any deductible
to be treated as a current Operating Expense), promptly restore the Premises
(excluding the improvements installed by Tenant or by Landlord and paid for by
Tenant but including items paid for out of the Tl Fund), subject to delays
arising from the collection of insurance proceeds, from Force Majeure events or
as needed to obtain any license, clearance or other authorization of any kind
required to enter into and restore the Premises issued by any governmental or
quasi-governmental agency having jurisdiction over the use, storage, release or
removal of Hazardous Materials in, on or about the Premises (collectively
referred to herein as "Hazardous Materials Clearances"); provided, however, that
if repair or restoration of the Premises is not Substantially Complete as of the
end of 12 months from the date of damage or destruction, Landlord may, in its
sole and absolute discretion, elect not to proceed with such repair and
restoration, in which event Landlord shall be relieved of its obligation to make
such repairs or restoration and this Lease shall terminate as of the date that
is 5 days after written notice to Tenant of Landlord's election to terminate
this Lease. If repair or restoration of the Premises is not Substantially
Complete as of the end of 12 months from the date of damage or destruction,
Tenant shall have the right to terminate this Lease upon the date that is 5 days
after written notice to Landlord of Tenant's election to terminate this Lease;
provided, however, that Tenant's right to terminate shall expire if not
exercised within 10 days after the end of 12 months from the date of damage or
destruction. Notwithstanding the foregoing, if insurance proceeds are not
available for restoration of the Premises or the Building solely by reason of
Landlord's failure to maintain the insurance required to be maintained by
Landlord under Section 17 hereof, Landlord shall be responsible for the costs of
restoration to the extent of the insurance proceeds that would have been
available had Landlord performed its obligations pursuant to Section 17 hereof.

     Tenant, at its expense, shall promptly perform, subject to delays arising
from the collection of insurance proceeds, from Force Majeure events or to
obtain Hazardous Material

<PAGE>

Clearances, all repairs or restoration not required to be done by Landlord and
shall promptly re-enter the Premises and commence doing business in accordance
with this Lease. Notwithstanding the foregoing, (i) Landlord may terminate this
Lease if the Premises are damaged during the last 2 years of the Term and
Landlord reasonably estimates that it will take more than one month to repair
such damage, or if insurance proceeds are not available for such restoration,
and (ii) Tenant may terminate this Lease if the Premises are damaged during the
last 12 months of the Term and Landlord reasonably estimates that it will take
more than 90 days to repair such damage; provided, however, Tenant's right to
terminate shall expire if not exercised within 5 days after Landlord's notice to
Tenant stating how long repairs are estimated to take. Rent shall be abated from
the date all required Hazardous Material Clearances are obtained until the
Premises are repaired and restored, in the proportion which the area of the
Premises, if any, which is not usable by Tenant bears to the total area of the
Premises, unless Landlord provides Tenant with other space during the period of
repair that is suitable for the temporary conduct of Tenant's business. Such
abatement shall be the sole remedy of Tenant, and except as provided herein,
Tenant waives any right to terminate the Lease by reason of damage or casualty
loss.

     The provisions of this Lease, including this Section 18, constitute an
express agreement between Landlord and Tenant with respect to any and all damage
to, or destruction of, all or any part of the Premises, or any other portion of
the Project, and any statute or regulation which is now or may hereafter be in
effect, shall have no application to this Lease or any damage or destruction to
all or any part of the Premises or any other portion of the Project, the parties
hereto expressly agreeing this Section 1 8 sets forth their entire understanding
and agreement with respect to such matters.

     19. CONDEMNATION. If any part of the Premises or the Project is taken for
any public or quasi-public use under governmental law, ordinance, or regulation,
or by right of eminent domain, or by private purchase in lieu thereof (a
"TAKING" or "TAKEN"), and the Taking would in Landlord's judgment either prevent
or materially interfere with Tenant's use of the Premises or materially
interfere with or impair Landlord's ownership or operation of the Project, then
upon written notice by Landlord this Lease shall terminate and Rent shall be
apportioned as of said date. If all or part of the Premises is taken and Tenant
is unable to use the Premises for the Permitted Use, Tenant shall have the right
to terminate this Lease upon the date that is 5 days after written notice to
Landlord of Tenant's election to terminate this Lease and Rent shall be
apportioned as of said date; provided, however, that Tenant's right to terminate
shall expire if not exercised within 10 days after the date of the order of
condemnation. If part of the Premises shall be Taken, and this Lease is not
terminated as provided above, Landlord shall promptly restore the Premises and
the Project as nearly as is commercially reasonable under the circumstances to
their condition prior to such partial taking and the Rent payable hereunder
during the unexpired Term shall be reduced to such extent as may be fair and
reasonable under the circumstances. Upon any such Taking, Landlord shall be
entitled to receive the entire price or award from any such Taking without any
payment to Tenant, and Tenant hereby assigns to Landlord Tenant's interest, if
any, in such award. Tenant shall have the right, to the extent that same shall
not diminish Landlord's award, to make a separate claim against the condemning
authority (but not Landlord) for such compensation as may be separately awarded
or recoverable by Tenant for moving expenses and damage to Tenant's Trade
Fixtures, if a separate award for such items is made to Tenant. Tenant hereby
waives any and all rights it might otherwise have

<PAGE>

pursuant to any provision of state law to terminate this Lease upon a partial
Taking of the Premises or the Project.

     20. EVENTS OF DEFAULT. Each of the following events shall be a default
("Default") by Tenant under this Lease:

     (a) PAYMENT DEFAULTS. Tenant shall fail to pay any installment of Rent or
any other payment hereunder when due; PROVIDED, HOWEVER, that Landlord, not more
than once in any 12 month period, will give Tenant notice of such default in the
payment of Rent and Tenant shall have 3 days in which to make such payment after
which period Tenant shall be in Default hereunder. Tenant agrees that such
notice shall be in lieu of and not in addition to any notice required by law.

     (b) INSURANCE. Any insurance required to be maintained by Tenant pursuant
to this Lease shall be canceled or terminated or shall expire or shall be
reduced or materially adversely changed, or Landlord shall receive a notice of
nonrenewal of any such insurance and Tenant shall fail to obtain replacement
insurance at least 20 days before the expiration of the current coverage.

     (c) ABANDONMENT. Tenant shall abandon the Premises and otherwise be in
default under this Lease.

     (d) IMPROPER TRANSFER. Tenant shall assign, sublease or otherwise transfer
or attempt to transfer all or any portion of Tenant's interest in this Lease or
the Premises except as expressly permitted herein, or Tenant's interest in this
Lease shall be attached, executed upon, or otherwise judicially seized and such
action is not released within 90 days of the action.

     (e) LIENS. Tenant shall fail to discharge or otherwise obtain the release
of any lien placed upon the Premises in violation of this Lease within 10 days
after Tenant has received notice that any such lien is filed against the
Premises.

     (f) INSOLVENCY EVENTS. Tenant or any guarantor or surety of Tenant's
obligations hereunder shall: (A) make a general assignment for the benefit of
creditors; (B) commence any case, proceeding or other action seeking to have an
order for relief entered on its behalf as a debtor or to adjudicate it a
bankrupt or insolvent, or seeking reorganization, arrangement, adjustment,
liquidation, dissolution or composition of it or its debts or seeking
appointment of a receiver, trustee, custodian or other similar official for it
or for all or of any substantial part of its property (collectively a
"PROCEEDING FOR RELIEF"); (C) become the subject of any Proceeding for Relief
which is not dismissed within 90 days of its filing or entry; or (D) die or
suffer a legal disability (if Tenant, guarantor, or surety is an individual) or
be dissolved or otherwise fail to maintain its legal existence (if Tenant,
guarantor or surety is a corporation, partnership or other entity).

     (g) ESTOPPEL CERTIFICATE OR SUBORDINATION AGREEMENT. Tenant fails to
execute any document required from Tenant under Sections 23 or 27 within 10 days
after a second notice requesting such document.

<PAGE>

     (h) OTHER DEFAULTS. Tenant shall fail to comply with any provision of this
Lease other than those specifically referred to in this Section 20*, and except
as otherwise expressly provided herein, such failure shall continue for a period
of 10 days after written notice thereof from Landlord to Tenant.

Any notice given under Section 20 (h) hereof, shall: (i) specify the alleged
default, (ii) demand that Tenant cure such default, (iii) be in lieu of, and not
in addition to, or shall be deemed to be any notice required under any provision
of applicable law, and (iv) not be deemed a forfeiture or a termination of this
Lease unless Landlord elects otherwise in such notice; PROVIDED that if the
nature of Tenant's default pursuant to Section 20(h) is such that it cannot be
cured by the payment of money and reasonably requires more than 10 days to cure,
then Tenant shall not be deemed to be in default if Tenant commences such cure
within said 10 day period and thereafter diligently prosecutes the same to
completion; provided, however, that such cure shall be completed no later than
90 days from the date of Landlord's notice.

     21. LANDLORD'S REMEDIES.

     (a) PAYMENT BY LANDLORD; INTEREST. Upon a Default by Tenant hereunder,
Landlord may, without waiving or releasing any obligation of Tenant hereunder,
make such payment or perform such act. All sums so paid or incurred by Landlord,
together with interest thereon, from the date such sums were paid or incurred,
at the annual rate equal to 12% per annum or the highest rate permitted by law
(the "Default Rate"), whichever is less, shall be payable to Landlord on demand
as Additional Rent. Nothing herein shall be construed to create or impose a duty
on Landlord to mitigate any damages resulting from Tenant's Default hereunder.

     (b) LATE PAYMENT RENT. Late payment by Tenant to Landlord of Rent and other
sums due will cause Landlord to incur costs not contemplated by this Lease, the
exact amount of which will be extremely difficult and impracticable to
ascertain. Such costs include, but are not limited to, processing and accounting
charges and late charges which may be imposed on Landlord under any Mortgage
covering the Premises. Therefore, if any installment of Rent due from Tenant is
not received by Landlord within 5 days after the date such payment is due,
Tenant shall pay to Landlord an additional sum of 6% of the overdue Rent as a
late charge. The parties agree that this late charge represents a fair and
reasonable estimate of the costs Landlord will incur by reason of late payment
by Tenant. In addition to the late charge, Rent not paid when due shall bear
interest at the Default Rate from the 5th day after the date due until paid.

     (c) REMEDIES. Upon the occurrence of a Default, Landlord, at its option,
without further notice or demand to Tenant, shall have in addition to all other
rights and remedies provided in this Lease, at law or in equity, the option to
pursue any one or more of the following remedies, each and all of which shall be
cumulative and nonexclusive, without any notice or demand whatsoever.

         (i) Terminate this Lease, or at Landlord's option, Tenant's right to
possession only, in which event Tenant shall immediately surrender the Premises
to Landlord, and if Tenant fails to do so, Landlord may, without prejudice to
any other remedy which it may have for possession or arrearages in rent, enter
upon and take possession of the Premises and expel or

<PAGE>

remove Tenant and any other person who may be occupying the Premises or any part
thereof, without being liable for prosecution or any claim or damages therefor;

         (ii) Upon any termination of this Lease, whether pursuant to the
foregoing Section 21(c)(i) or otherwise, Landlord may recover from Tenant the
following:

              (A) The worth at the time of award of any unpaid rent which has
been earned at the time of such termination; plus

              (B) The worth at the time of award of the amount by which the
unpaid rent which would have been earned after termination until the time of
award exceeds the amount of such rental loss that Tenant proves could have been
reasonably avoided; plus

              (C) The worth at the time of award of the amount by which the
unpaid rent for the balance of the Term after the time of award exceeds the
amount of such rental loss that Tenant proves could have been reasonably
avoided; plus

              (D) Any other amount necessary to compensate Landlord for all the
detriment proximately caused by Tenant's failure to perform its obligations
under this Lease or which in the ordinary course of things would be likely to
result therefrom, specifically including but not limited to, brokerage
commissions and advertising expenses incurred, expenses of remodeling the
Premises or any portion thereof for a new tenant, whether for the same or a
different use; and

              (E) At Landlord's election, such other amounts in addition to or
in lieu of the foregoing as may be permitted from time to time by applicable
law.

     The term "RENT" as used in this Section 21 shall be deemed to be and to
mean all sums of every nature required to be paid by Tenant pursuant to the
terms of this Lease, whether to Landlord or to others. As used in Sections 21
(c)(ii) (A) and (B), above, the "WORTH AT THE TIME OF AWARD" shall be computed
by allowing interest at the Default Rate. As used in Section 21 (c)(ii)(C)
above, the "WORTH AT THE TIME OF AWARD" shall be computed by discounting such
amount at the discount rate of the Federal Reserve Bank of San Francisco at the
time of award plus 1%.

         (iii) Landlord may continue this Lease in effect after Tenant's Default
and recover rent as it becomes due. Accordingly, if Landlord does not elect to
terminate this Lease following a Default by Tenant, Landlord may, from time to
time, without terminating this Lease, enforce all of its rights and remedies
hereunder, including the right to recover all Rent as it becomes due.

         (iv) Whether or not Landlord elects to terminate this Lease following a
Default by Tenant, Landlord shall have the right to terminate any and all
subleases, licenses, concessions or other consensual arrangements for possession
entered into by Tenant and affecting the Premises or may, in Landlord's sole
discretion, succeed to Tenant's interest in such subleases, licenses,
concessions or arrangements. Upon Landlord's election to succeed to Tenant's
interest in any such subleases, licenses, concessions or arrangements, Tenant
shall, as

<PAGE>

of the date of notice by Landlord of such election, have no further right to or
interest in the rent or other consideration receivable thereunder.

         (v) Independent of the exercise of any other remedy of Landlord
hereunder or under applicable law, Landlord may conduct an environmental test of
the Premises as generally described in Section 30(d) hereof. If contamination
has occurred for which Tenant is liable under Section 30 hereof, Tenant shall
pay all costs to conduct such tests. If no such contamination is found, Landlord
shall pay the costs of such tests.

     (d) EFFECT OF EXERCISE. Exercise by Landlord of any remedies hereunder or
otherwise available shall not be deemed to be an acceptance of surrender of the
Premises and/or a termination of this Lease by Landlord, it being understood
that such surrender and/or termination can be effected only by the express
written agreement of Landlord and Tenant. Any law, usage, or custom to the
contrary notwithstanding, Landlord shall have the right at all times to enforce
the provisions of this Lease in strict accordance with the terms hereof; and the
failure of Landlord at any time to enforce its rights under this Lease strictly
in accordance with same shall not be construed as having created a custom in any
way or manner contrary to the specific terms, provisions, and covenants of this
Lease or as having modified the same and shall not be deemed a waiver of
Landlord's right to enforce one or more of its rights in connection with any
subsequent default. A receipt by Landlord of Rent or other payment with
knowledge of the breach of any covenant hereof shall not be deemed a waiver of
such breach, and no waiver by Landlord of any provision of this Lease shall be
deemed to have been made unless expressed in writing and signed by Landlord. To
the greatest extent permitted by law, Tenant waives the service of notice of
Landlord's intention to re-enter, re-take or otherwise obtain possession of the
Premises as provided in any statute, or to institute legal proceedings to that
end, and 'also waives all right of redemption in case Tenant shall be
dispossessed by a judgment or by warrant of any court or judge. Any reletting of
the Premises or any portion thereof shall be on such terms and conditions as
Landlord in its sole discretion may determine. Landlord shall not be liable, nor
shall Tenant's obligations hereunder be diminished because of, Landlord's
failure to relet the Premises or collect rent due in respect of such reletting
or otherwise to mitigate any damages arising by reason of Tenant' Default.

     22. ASSIGNMENT AND SUBLETTING.

     (a) GENERAL PROHIBITION. Except for subleasing a portion of the Premises to
Antigen Express, Inc., and E-Z-Em, Inc., without Landlord's prior written
consent subject to and on the conditions described in this Section 22, Tenant
shall not, directly or indirectly, voluntarily or by operation of law, assign
this Lease or sublease the Premises or any part thereof or mortgage, pledge, or
hypothecate its leasehold interest or grant any concession or license within the
Premises and any attempt to do any of the foregoing shall be void and of no
effect. If Tenant is a corporation, partnership or limited liability company,
the shares or other ownership interests of Tenant which are not actively traded
'upon a stock exchange or in the over-the-counter market, a transfer or series
of transfers whereby 35% or more of the issued and outstanding shares or other
ownership interests of such corporation are, or voting control, is, transferred
("Stock Transfer") (but excepting transfers upon deaths of individual owners or
for estate planning purposes) from a person or persons or entity or entities
which were owners thereof at time of execution of this Lease to persons or
entities who were not owners of shares of the corporation, partnership or

<PAGE>

limited liability company at time of execution of this Lease, shall be deemed an
assignment of this Lease requiring the consent of Landlord. Landlord may in
connection with a Stock Transfer request and consider such information as
Landlord deems necessary or appropriate to its consideration whether to grant
its consent to such Stock Transfer. Landlord shall grant or refuse such consent
in its reasonable discretion; provided, however, that Tenant acknowledges that
it shall be reasonable for Landlord to refuse consent to any assignment which
(i) may have the potential to negatively impact the financial condition of
Tenant or the likelihood or ability of Tenant to perform its obligations under
this Lease, (ii) is not for a rational business purpose, or (iii) is principally
for the purpose of transferring the Lease.

     (b) Permitted Transfers. If Tenant desires to assign, sublease, hypothecate
or otherwise transfer this Lease or sublet the Premises, then at least 15
business days, but not more than 45 business days, before the date Tenant
desires the assignment or sublease to be effective (the "ASSIGNMENT DATE"),
Tenant shall give Landlord a notice (the "ASSIGNMENT NOTICE") containing such
information about the proposed assignee or sublessee, including the proposed use
of the Premises and any Hazardous Materials proposed to be used or stored in the
Premises, the Assignment Date, any relationship between Tenant and the proposed
assignee or sublessee, and all material terms and conditions of the proposed
assignment or sublease, including a copy of any proposed sublease in its final
form, and such other information as Landlord may deem reasonably necessary or
appropriate to its consideration whether to grant its consent. Landlord may, by
giving written notice to Tenant within 1 5 business days after receipt of the
Assignment Notice: (i) grant or refuse such consent, in its sole discretion with
respect to a proposed assignment, hypothecation or other transfer or subletting
of more than (together with all other then effective subleases) 50% of the
Premises, or grant or refuse such consent, in its reasonable discretion with
respect to a proposed subletting of up to (together with all other then
effective subleases) 50% of the Premises (provided that Landlord shall further
have the right to review and approve or disapprove the proposed form of sublease
prior to the effective date of any such subletting), or with respect to a Stock
Transfer, or (ii) terminate this Lease with respect to they space described in
the Assignment Notice, as of the Assignment Date (an "Assignment Termination").
If Landlord elects an Assignment Termination, Tenant shall have the right to
withdraw such Assignment Notice by written notice to Landlord of such election
within 10 days after Landlord's notice electing to exercise the Assignment
Termination. If Tenant withdraws such Assignment Notice, this Lease shall
continue in full force and effect. If Tenant does not withdraw such Assignment
Notice, this Lease, and the term and estate herein granted, shall terminate as
of the Assignment Date with respect to the space described in such Assignment
Notice. No failure of Landlord to exercise any such option to terminate this
Lease shall be deemed to be Landlord's consent to the proposed assignment,
sublease or other transfer. Tenant shall reimburse Landlord for all of
Landlord's reasonable out-of-pocket expenses in connection with its
consideration of any Assignment Notice.

     (c) Additional Conditions. As a condition to any such assignment or
subletting, whether or not Landlord's consent is required, Landlord may require:

         (i) that any assignee or subtenant agree, in writing at the time of
such assignment or subletting, that, following the occurrence of a Default
hereunder, if Landlord gives such party written notice that Tenant is in default
under this Lease, such party shall thereafter make all payments otherwise due
Tenant directly to Landlord, which payments will be received

<PAGE>

by Landlord without any liability except to credit such payment against those
due under the Lease, and any such third party shall agree to attorn to Landlord
or its successors and assigns should this Lease be terminated for any reason;
PROVIDED, HOWEVER, in no event shall Landlord or its successors or assigns be
obligated to accept such attornment; and

     A list of Hazardous Materials, certified by the proposed assignee or
sublessee to be true and correct, which the proposed assignee or sublessee
intends to use or store in the Premises together with copies of all documents
relating to the handling, storage, disposal and emission of Hazardous Materials
by the proposed assignee or subtenant in the Premises or on the Project, prior
to the proposed assignment or subletting, including, without limitation:
permits; approvals; reports and correspondence; storage and management plans;
plans relating to the installation of any storage tanks to be installed in or
under the Project (provided, said installation of tanks shall only be permitted
after Landlord has given its written consent to do so, which consent may be
withheld in Landlord's sole and absolute discretion); and all closure plans or
any other documents required by any and all federal, state and local
governmental agencies and authorities for any storage tanks installed in, on or
under the Project for the closure of any such tanks. Neither Tenant nor any such
proposed assignee or subtenant is required, however, to provide Landlord with
any portion(s) of the such documents containing information of a proprietary
nature which, in and of themselves, do not contain a reference to any Hazardous
Materials or hazardous activities.

     (d) NO RELEASE OF TENANT, SHARING OF EXCESS RENTS. Notwithstanding any
assignment or subletting, Tenant and any guarantor or surety of Tenant's
obligations under this Lease shall at all times remain fully and primarily
responsible and liable for the payment of Rent and for compliance with all of
Tenant's other obligations under this Lease. If the Rent due and payable by a
sublessee or assignee (or a combination of the rental payable under such
sublease or assignment plus any bonus or other consideration therefor or
incident thereto) exceeds the rental payable under this Lease, (excluding
however, any Rent payable under this Section), then Tenant shall be bound and
obligated to pay Landlord as Additional Rent hereunder 50% of such excess rental
and other excess consideration within 10 days following receipt thereof by
Tenant. If Tenant shall sublet the Premises or any part thereof, Tenant hereby
immediately and irrevocably assigns to Landlord, as security for Tenant's
obligations under this Lease, all rent from any such subletting and Landlord as
assignee and as attorney-in-fact for Tenant, or a receiver for Tenant appointed
on Landlord's application, may collect such rent and apply it toward Tenant's
obligations under this Lease; except that, until the occurrence of a Default,
Tenant shall have the right to collect such rent.

     (e) NO WAIVER. The consent by Landlord to an assignment or subletting shall
not relieve Tenant or any assignees of this Lease or any sublessees of the
Premises from obtaining the consent of Landlord to any further assignment or
subletting nor shall it release Tenant or any assignee or sublessee of Tenant
from full and primary liability under the Lease. The acceptance of Rent
hereunder, or the acceptance of performance of any other term, covenant, or
condition thereof, from any other person or entity shall not be deemed to be a
waiver of any of the provisions of this Lease or a consent to any subletting,
assignment or other transfer of the Premises.

<PAGE>

     (f) TERMINATION OF LEASE. Notwithstanding any other provision of this
Section 22, if (i) the proposed assignee or sublessee of Tenant has been
required by any prior landlord, lender or governmental authority to take
remedial action in connection with Hazardous Materials contaminating a property,
where the contamination resulted from such party's action or use of the property
in question, or (ii) the proposed assignee or sublessee is subject to an
enforcement order issued by any governmental authority in connection with the
use, disposal or storage of a Hazardous Materials, Landlord shall have the
absolute right to refuse to consent to any assignment or subletting to any such
party.

     23. ESTOPPEL CERTIFICATE. Tenant shall within 10 business days after
written notice from Landlord, execute, acknowledge and deliver a statement in
writing substantially in the form attached to this Lease as EXHIBIT G with the
blanks filled in, and on any other form reasonably requested by a proposed
lender or purchaser, (i) certifying that this Lease is unmodified and in full
force and effect (or, if modified, stating the nature of such modification and
certifying that this Lease as so modified is in full force and effect) and the
dates to which the rental and other charges are paid in advance, if any, (ii)
acknowledging that there are not any uncured defaults on the part of Landlord
hereunder, or specifying such defaults if any are claimed, and (iii) setting
forth such further information with respect to the status of this Lease or the
Premises as may be reasonably requested thereon. Any such statement may be
relied upon by any prospective purchaser or encumbrancer of all or any portion
of the real property of which the Premises are a part. Tenant's failure to
deliver such statement within such time shall, at the option of Landlord,
constitute a Default under this Lease, and, in any event, shall be conclusive
upon Tenant that the Lease is in full force and effect and without modification
except as may be represented by Landlord in any certificate prepared by Landlord
and delivered to Tenant for execution.

     24. QUIET ENJOYMENT. So long as Tenant shall perform all of the covenants
and agreements herein required to be performed by Tenant, Tenant shall, subject
to the terms of this Lease, at all times during the Term, have peaceful and
quiet enjoyment of the Premises against any person claiming by, through or under
Landlord.

     25. PRORATIONS. All prorations required or permitted to be made hereunder
shall be made on the basis of a 360 day year and 30 day months.

     26. RULES AND REGULATIONS. Tenant shall, at all times during the Term and
any extension thereof, comply with all reasonable rules and regulations at any
time or from time to time established by Landlord covering use of the Premises
and the Project. The current rules and regulations are attached hereto as
Exhibit E. If there is any conflict between said rules and regulations and other
provisions of this Lease, the terms and provisions of this Lease shall control.
Landlord shall not have any liability or obligation for the breach of any rules
or regulations by other tenants in the Project.

     27. SUBORDINATION. This Lease and Tenant's interest and rights hereunder
are and shall be subject and subordinate at all times to the lien of any
Mortgage, now existing or hereafter created on or against the Project or the
Premises, and all amendments, restatements, renewals, modifications,
consolidations, refinancing, assignments and extensions thereof, without the
necessity of any further instrument or act on the part of Tenant; provided,
however that so long as there is no Default hereunder, Tenant's right to
possession of the Premises shall

<PAGE>

not be disturbed by the Holder of any such Mortgage. Tenant agrees, at the
election of the Holder of any such Mortgage, to attorn to any such Holder.
Tenant agrees upon demand to execute, acknowledge and deliver a Subordination,
Non-disturbance and Attornment Agreement in the form attached hereto as Exhibit
H, or such other instruments, confirming such subordination and such instruments
of attornment as shall be requested by any such Holder, provided any such
instruments contain appropriate non-disturbance provisions assuring Tenant's
quiet enjoyment of the Premises as set forth in Section 24 hereof and a copy of
the same executed by any such Holder is delivered to Tenant. Notwithstanding the
foregoing, any such Holder may at any time subordinate its Mortgage to this
Lease, without Tenant's consent, by notice in writing to Tenant, and thereupon
this Lease shall be deemed prior to such Mortgage without regard to their
respective dates of execution, delivery or recording and in that event such
Holder shall have the same rights with respect to this Lease as though this
Lease had been executed prior to the execution, delivery and recording of such
Mortgage and had been assigned to such Holder. The term "Mortgage" whenever used
in this Lease shall be deemed to include deeds of trust, security assignments
and any other encumbrances, and any reference to the "Holder" of a mortgage
shall be deemed to include the beneficiary under a deed of trust.

     28. SURRENDER. Upon expiration of the Term or earlier termination of
Tenant's right of possession, Tenant shall surrender the Premises to Landlord in
the same condition as received, subject to any Alterations permitted by Landlord
to remain in the Premises, free of Hazardous Materials brought upon, kept or
used in or about the Premises or the Project by any person other than Landlord,
its agents, employees, contractors or invitees and released of all Hazardous
Materials Clearances, broom clean, ordinary wear and tear and casualty loss and
condemnation excepted. Tenant shall immediately return to Landlord all keys
and/or access cards to parking, the Project, restrooms or all or any portion of
the Premises furnished to, or otherwise procured by Tenant. If any such access
card or key is lost, Tenant shall pay to Landlord, at Landlord's election,
either the cost of replacing such lost access card or key or the cost of
reprogramming the access security system in which such access card was used or
changing the lock or locks opened by such lost key. Any Tenant's Property,
Alterations and property not so removed by Tenant as permitted or required
herein shall be deemed abandoned and may be stored, removed, and disposed of by
Landlord at Tenant's expense, and Tenant waives all claims against Landlord for
any damages resulting from Landlord's retention and/or disposition of such
property. All obligations of Tenant hereunder not fully performed as of the
termination of the Term, including the obligations of Tenant under Section 30
hereof, shall survive the expiration or earlier termination of the Term,
including without limitation, indemnity obligations, payment obligations with
respect to Rent and obligations concerning the condition and repair of the
Premises for a period of three (3) years after expiration or earlier
termination of the Term.

     29. WAIVER OF JURY TRIAL. TENANT AND LANDLORD WAIVE ANY RIGHT TO TRIAL BY
JURY OR TO HAVE A JURY PARTICIPATE IN RESOLVING ANY DISPUTE, WHETHER SOUNDING IN
CONTRACT, TORT, OR OTHERWISE, BETWEEN LANDLORD AND TENANT ARISING OUT OF THIS
LEASE OR ANY OTHER INSTRUMENT, DOCUMENT, OR AGREEMENT EXECUTED OR DELIVERED IN
CONNECTION HEREWITH OR THE TRANSACTIONS RELATED HERETO.

     30. ENVIRONMENTAL REQUIREMENTS.

<PAGE>

     (a) PROHIBITION/COMPLIANCE/INDEMNITY. Tenant shall not cause or permit any
Hazardous Materials (as hereinafter defined) to be brought upon, kept or used in
or about the Premises or the Project in violation of applicable law by Tenant,
its agents, employees, contractors or invitees. If Tenant breaches the
obligation stated in the preceding sentence, or if the presence of Hazardous
Materials in the Premises during the term of this Lease or Tenant's occupancy of
the Project results in contamination of the Premises, the Project or any
adjacent property or if contamination of the Premises, the Project or any
adjacent property by Hazardous Materials brought into the Premises by anyone
other than Landlord and Landlord's employees, agents and contractors otherwise
occurs during the term of this Lease or any extension or renewal hereof or
holding over hereunder, Tenant hereby indemnifies and shall defend and hold
Landlord, its officers, directors, employees, agents and contractors harmless
from any and all claims, judgments, damages, penalties, fines, costs,
liabilities, or losses (including, without limitation, diminution in value of
the Premises or any portion of the Project, damages for the loss or restriction
on use of rentable or usable space or of any amenity of the Premises or the
Project, damages arising from any adverse impact on marketing of space in the
Premises or the Project, and sums paid in settlement of claims, and reasonable
attorneys' fees, consultant fees and expert fees) which arise during or after
the Lease term as a result of such contamination. This indemnification of
Landlord by Tenant includes, without limitation, costs incurred in connection
with any investigation of site conditions or any cleanup, remedial, removal, or
restoration work required by any federal, state or local governmental agency or
political subdivision because of Hazardous Materials present in the air, soil or
ground water above, on, or under the Premises. Without limiting the foregoing,
if the presence of any Hazardous Materials on the Premises, the Project or any
adjacent property, caused or permitted by Tenant results in any contamination of
the Premises, the Project or any adjacent property, Tenant shall promptly take
all actions at its sole expense and in accordance with applicable law as are
necessary to return the Premises, the Project or any adjacent property, to the
condition existing as of the date hereof, provided that Landlord's approval of
such action shall first be obtained, which approval shall not unreasonably be
withheld so long as such actions would not potentially have any material adverse
long-term or short-term effect on the Premises or the Project.

     (b) BUSINESS. Landlord acknowledges that it is not the intent of this
Article 30 to prohibit Tenant from using the Premises for the Permitted Use.
Tenant may operate its business according to the custom of the industry so long
as the use or presence of Hazardous Materials is strictly and properly monitored
according to all applicable governmental requirements. As a material inducement
to Landlord to allow Tenant to use Hazardous Materials in connection with its
business, Tenant agrees to deliver to Landlord prior to the Commencement Date a
list identifying each type of Hazardous Materials to be present on the Premises
and setting forth any and all governmental approvals or permits required in
connection with the presence of such Hazardous Materials on the Premises
("HAZARDOUS MATERIALS LIST"). Tenant shall deliver to Landlord an updated
Hazardous Materials List at least once a year and shall also deliver an updated
list before any new Hazardous Material(s) is brought onto the Premises. Tenant
shall deliver to Landlord true and correct copies of the following documents
(the "HAZ MAT DOCUMENTS") relating to the handling, use, storage, disposal and
emission of Hazardous Materials prior to the Commencement Date, or if
unavailable at that time, concurrent with the receipt from or submission to a
governmental agency: permits; approvals; reports and correspondence; storage and
management plans, notice of violations of any laws; plans relating to the
installation of any storage tanks to be installed in or under the Project
(provided, said

<PAGE>

installation of tanks shall only be permitted after Landlord has given Tenant
its written consent to do so, which consent may be withheld in Landlord's sole
and absolute discretion); and all closure plans or any other documents required
by any and all federal, state and local governmental agencies and authorities
for any storage tanks installed in, on or under the Project for the closure of
any such tanks. Tenant is not required, however, to provide Landlord with any
portion(s) of the Haz Mat Documents containing information of a proprietary
nature which, in and of themselves, do not contain a reference to any Hazardous
Materials or hazardous activities. It is not the intent of this Section to
provide Landlord with information which could be detrimental to Tenant's
business should such information become possessed by Tenant's competitors.

     (c) TENANT REPRESENTATION AND WARRANTY. Tenant hereby represents and
warrants to Landlord that (i) neither Tenant nor any of its legal predecessors
has been required by any prior landlord, lender or governmental authority at any
time to take remedial action in connection with Hazardous Materials
contaminating a property which contamination was permitted by Tenant or such
predecessor or resulted from Tenant's or such predecessor's action or use of the
property in question, and (ii) Tenant is not subject to any enforcement order
issued by any governmental authority in connection with the use, disposal or
storage of a Hazardous Materials. If landlord determines that this
representation and warranty was not true as of the date of this lease, Landlord
shall have the right to terminate this Lease in Landlord's sole and absolute
discretion.

     (d) TESTING. Landlord shall have the right to conduct annual tests of the
Premises to determine whether any contamination has occurred as a result of
Tenant's use. Tenant shall be required to pay the cost of such annual test of
the Premises; provided, however, that if Tenant conducts its own tests of the
Premises using third party contractors and test procedures reasonably acceptable
to Landlord which tests are certified to Landlord, Landlord shall accept such
tests in lieu of the annual tests to be paid for by Tenant. In addition, at any
time, and from time to time, prior to the expiration or earlier termination of
the Term, Landlord shall have the right to conduct appropriate tests of the
Premises and the Project to determine if contamination has occurred as a result
of Tenant's use of the Premises. If contamination has occurred for which Tenant
is liable under this Section 30, Tenant shall pay all costs to conduct such
tests. If no such contamination is found, Landlord shall pay the costs of such
tests (which shall not constitute an Operating Expense). Landlord shall provide,
without representation or warranty and subject to a confidentiality agreement,
Tenant with a copy of all third party, non-confidential reports and tests of the
Premises made by or on behalf of Landlord. Tenant shall be solely responsible
for and shall defend, indemnify and hold Landlord, its agents and contractors
harmless from and against any and all claims, costs and liabilities including
actual attorneys' fees, charges and disbursement, arising out of or in
connection with any removal, clean up, restoration and materials required
hereunder to return the Premises and any other property of whatever nature to
their condition existing as of the date hereof. Landlord's receipt of or
satisfaction with any environmental assessment in no way waives any rights that
Landlord holds against Tenant.

     (e) UNDERGROUND TANKS. If underground or other storage tanks storing
Hazardous Materials located on the Premises are used by Tenant Or are hereafter
placed on the Premises by Tenant, Tenant shall monitor the storage tanks,
maintain appropriate records, implement reporting procedures, properly close any
underground storage tanks, and take or cause to be

<PAGE>

taken all other actions necessary or required under applicable state and federal
law, as such now exists or may hereafter be adopted or amended.

     (f) TENANT'S OBLIGATIONS. Tenant's obligations under this Article 30 shall
survive the expiration or earlier termination of the Lease. During any period of
time after the expiration or earlier termination of this Lease required by
Tenant or Landlord to complete the removal from the Premises of any Hazardous
Materials and the release and termination of any licenses or permits restricting
the use of the Premises, Tenant shall continue to pay the full Rent in
accordance with this Lease for any portion of the Premises not relet by Landlord
in Landlord's sole discretion, which Rent shall be prorated daily.

     (g) DEFINITIONS. As used herein, the term "Environmental Requirements"
means all applicable present and future statutes, regulations, ordinances,
rules, codes, judgments, orders or other similar enactments of any governmental
authority or agency regulating or relating to health, safety, or environmental
conditions on, under, or about the Premises or the environment, including
without limitation, the following: the Comprehensive Environmental Response,
Compensation and Liability Act; the Resource Conservation and Recovery Act; and
all state and local counterparts thereto, and any regulations or policies
promulgated or issued thereunder. As used herein, the term "Hazardous Materials"
means and includes any substance, material, waste, pollutant, or contaminant
listed or defined as hazardous or toxic, or regulated by reason of its impact or
potential impact on humans, animals and/or the environment under any
Environmental Requirements, asbestos and petroleum, including crude oil or any
fraction thereof, natural gas liquids, liquefied natural gas, or synthetic gas
usable for fuel (or mixtures of natural gas and such synthetic gas). As defined
in Environmental Requirements, Tenant is and shall be deemed to be the operator"
of Tenant's "facility" and the "owner" of all Hazardous Materials brought on the
Premises by Tenant, its agents, employees, contractors or invitees, and the
wastes, by-products, or residues generated, resulting, or produced therefrom.

     31. TENANT'S REMEDIES/LIMITATION OF LIABILITY. Landlord shall not be in
default hereunder unless Landlord fails to perform any of its obligations
hereunder within 30 days after written notice from Tenant specifying such
failure (unless such performance will, due to the nature of the obligation,
require a period of time in excess of 30 days, then after such period of time as
is reasonably necessary). Upon any default by Landlord, Tenant shall give notice
by registered or certified mail to any Holder of a Mortgage covering the
Premises and to any landlord of any lease of property in or on which the
Premises are located and Tenant shall offer such beneficiary, Holder and/or
landlord a reasonable opportunity to cure the default, including time to obtain
possession of the Project by power of sale or a judicial action if such should
prove necessary to effect a cure; provided Landlord shall have furnished to
Tenant in writing the names and addresses of all such persons who are to receive
such notices. All obligations of Landlord hereunder shall be construed as
covenants, not conditions; and, except as may be otherwise expressly provided in
this Lease, Tenant may not terminate this Lease for breach of Landlord's
obligations hereunder.

     All obligations of Landlord under this Lease will be binding upon Landlord
only during the period of its ownership of the Premises and not thereafter. The
term "Landlord" in this Lease shall mean only the owner, for the time being of
the Premises, and upon the transfer by such owner of its interest in the
Premises, such owner shall thereupon be released and discharged from

<PAGE>

all obligations of Landlord thereafter accruing, but such obligations shall be
binding during the Term upon each new owner for the duration of such owner's
ownership.

     32. INSPECTION AND ACCESS. Landlord and its agents, representatives, and
contractors may enter the Premises at any reasonable time to inspect the
Premises and to make such repairs as may be required or permitted pursuant to
this Lease and for any other business purpose. Landlord and Landlord's
representatives may enter the Premises during business hours on not less than 48
hours advance written notice (except in the case of emergencies in which case no
 .such notice shall be required and such entry may be at any time but Landlord
shall nonetheless be required to provide notice to Tenant of such emergency
entry as soon as practicable) for the purpose of effecting any such repairs,
inspecting the Premises, showing the Premises to prospective purchasers and,
during the last year of the Term, to prospective tenants or for any other
business purpose. Landlord may erect a suitable sign on the Premises stating the
Premises are available to let (within the last 9 months of the Term) or that the
Project is available for sale. Landlord may grant easements, make public
dedications, designate common areas and create restrictions on or about the
Premises, PROVIDED that no such easement, dedication, designation or restriction
materially, adversely affects Tenant's use or occupancy of the Premises for the
Permitted use. At Landlord's request, Tenant shall execute such instruments as
may be necessary for such easements, dedications or restrictions. Tenant shall
at all times, except in the case of emergencies, have the right to escort
Landlord or its agents, representatives, contractors or guests while the same
are in the Premises, provided such escort does not materially and adversely
affect Landlord's access rights hereunder.

     33. SECURITY. Tenant acknowledges and agrees that security devices and
services, if any, while intended to deter crime may not in given instances
prevent theft or other criminal acts and that Landlord is not providing any
security services with respect to the Premises. Tenant agrees that Landlord
shall not be liable to Tenant for, and Tenant waives any claim against Landlord
with respect to, any loss by theft or any other damage suffered or incurred by
Tenant in connection with any unauthorized entry into the Premises or any other
breach of security with respect to the Premises. Tenant shall be solely
responsible for the. personal safety of Tenant's officers, employees, agents,
contractors, guests and invitees while any such person is in, on or about the
Premises and/or the Project. Tenant shall at Tenant's cost obtain insurance
coverage to the extent Tenant desires protection against such criminal acts.

     34. FORCE MAJEURE. Except for the payment of Rent and Additional Rent,
neither Landlord nor Tenant shall be held responsible for delays in the
performance of their obligations hereunder when caused by strikes, lockouts,
labor disputes, weather, natural disasters, inability to obtain labor or
materials or reasonable substitutes therefor, governmental restrictions,
governmental regulations, governmental controls, delay in issuance of permits,
enemy or hostile governmental action, civil commotion, fire or other casualty,
and other causes beyond their reasonable control ("FORCE MAJEURE").

     35. BROKERS, ENTIRE AGREEMENT, AMENDMENT. Landlord and Tenant each
represent and warrant that it has not dealt with any broker, agent or other
person (collectively, "Broker) in connection with this transaction and that no
Broker brought about this transaction, other than the Broker, if any, set forth
on the first page of this Lease. Landlord and Tenant each hereby agree to
indemnify and hold the other harmless from and against any claims by any other
Broker

<PAGE>

claiming a commission or other form of compensation by virtue of having dealt
with Tenant or Landlord, as applicable, with regard to this leasing transaction.
This Lease may not be amended except by an instrument in writing signed by both
parties hereto.

     36. LIMITATION ON LANDLORD'S LIABILITY. NOTWITHSTANDING ANYTHING SET FORTH
HEREIN OR IN ANY OTHER AGREEMENT BETWEEN LANDLORD AND TENANT TO THE CONTRARY:
(A) LANDLORD SHALL NOT BE LIABLE TO TENANT OR ANY OTHER PERSON FOR (AND TENANT
AND EACH SUCH OTHER PERSON ASSUME ALL RISK OF) LOSS, DAMAGE OR INJURY, WHETHER
ACTUAL OR CONSEQUENTIAL TO: TENANT'S PERSONAL PROPERTY OF EVERY KIND AND
DESCRIPTION, INCLUDING, WITHOUT LIMITATION TRADE FIXTURES, EQUIPMENT, INVENTORY,
SCIENTIFIC RESEARCH, SCIENTIFIC EXPERIMENTS, LABORATORY ANIMALS, PRODUCT,
SPECIMENS, SAMPLES, AND/OR SCIENTIFIC, BUSINESS, ACCOUNTING AND OTHER RECORDS OF
EVERY KIND AND DESCRIPTION KEPT AT THE PREMISES AND ANY AND ALL INCOME DERIVED
OR DERIVABLE THEREFROM; (B) THERE SHALL BE NO PERSONAL RECOURSE TO LANDLORD FOR
ANY ACT OR OCCURRENCE IN, ON OR ABOUT THE PREMISES OR ARISING IN ANY WAY UNDER
THIS LEASE OR ANY OTHER AGREEMENT BETWEEN LANDLORD AND TENANT WITH RESPECT TO
THE SUBJECT MATTER HEREOF AND ANY LIABILITY OF LANDLORD HEREUNDER SHALL BE
STRICTLY LIMITED SOLELY TO LANDLORD'S INTEREST IN THE PROJECT, AND IN NO EVENT
SHALL ANY PERSONAL LIABILITY BE ASSERTED AGAINST LANDLORD IN CONNECTION WITH
THIS LEASE NOR SHALL ANY RECOURSE BE HAD TO ANY OTHER PROPERTY OR ASSETS OF
LANDLORD OR ANY OF LANDLORD'S OFFICERS, EMPLOYEES, AGENTS OR CONTRACTORS. UNDER
NO CIRCUMSTANCES SHALL LANDLORD OR ANY OF LANDLORD'S OFFICERS, EMPLOYEES, AGENTS
OR CONTRACTORS BE LIABLE FOR INJURY TO TENANT'S BUSINESS OR FOR ANY LOSS OF
INCOME OR PROFIT THEREFROM.

     37. SEVERABILITY. If any clause or provision of this Lease is illegal,
invalid or unenforceable under present or future laws, then and in that event,
it is the intention of the parties hereto that the remainder of this Lease shall
not be affected thereby. It is also the intention of the parties to this Lease
that in lieu of each clause or provision of this Lease that is illegal, invalid
or unenforceable, there be added, as a part of this Lease, a clause or provision
as similar in terms to such illegal, invalid or unenforceable clause or
provision as may be possible and be legal, valid and enforceable.

     38. SIGNS; EXTERIOR APPEARANCE. Tenant shall not, without the prior written
consent of Landlord, which may be granted or withheld in Landlord's sole
discretion: (i) attach any awnings, exterior lights, decorations, balloons,
flags, pennants, banners, painting or other projection to any outside wall of
the Project, (ii) use any curtains, blinds, shades or screens other than
Landlord's standard window coverings, (iii) coat or otherwise sunscreen the
interior or exterior of any windows, (iv) place any bottles, parcels, or other
articles on the window sills, (v) place any equipment, furniture or other items
of personal property on any exterior balcony, (vi) paint, affix or exhibit on
any part of the Premises or the Project any signs, notices, window or door
lettering, placards, decorations, or advertising media of any type which can be
viewed from the exterior of the Premises. interior signs on doors and the
directory tablet shall be inscribed,

<PAGE>

painted or affixed for Tenant by Landlord at the sole cost and expense of
Tenant, and shall be of a size, color and type acceptable to Landlord. Nothing
may be placed on the exterior of corridor walls or corridor doors other than
Landlord's standard lettering. The directory tablet shall be provided
exclusively for the display of the name and location of tenants.

     39. RIGHT TO EXTEND TERM. Tenant shall have the right to extend the Term of
the Lease upon the following terms and conditions:

     (a) EXTENSION RIGHT. Tenant shall have the right (an "EXTENSION RIGHT") to
extend the term of this Lease for 5 years (an "EXTENSION TERM") on the same
terms and conditions as this Lease by giving Landlord written notice of its
election to exercise such Extension Right at least 9 months prior to the
expiration of the Base Term of the Lease. Base Rent shall be adjusted on the
commencement date of the Extension Term and on each annual anniversary of the
commencement of the Extension Term by multiplying the Base Rent payable
immediately before such adjustment by the Rent Adjustment Percentage and adding
the resulting amount to the Base Rent payable immediately before such
adjustment. in addition, Landlord may impose a market rent for the parking
rights provided hereunder.

     (b) RIGHTS PERSONAL. The Extension Right is personal to Tenant and is not
assignable without Landlord's consent, which may be granted or withheld in
Landlord's sole discretion.

     (c) EXCEPTIONS. Notwithstanding anything set forth above to the contrary,
the Extension Right shall not be in effect and Tenant may not exercise the
Extension Right:

         (i) during any period of time that Tenant is in Default under any
provision of this Lease; or

         (ii) if Tenant has been in Default under any provision of this Lease 3
or more times, whether or not the Defaults are cured, during the 12 month period
immediately prior to the date that Tenant intends to exercise the Extension
Right, whether or not the Defaults are cured.

     (d) NO EXTENSIONS. The period of time within which the Extension Right may
be exercised shall not be extended or enlarged by reason of the Tenant's
inability to exercise the Extension Right.

     (e) TERMINATION. The Extension Right shall terminate and be of no further
force or effect even after Tenant's due and timely exercise of the Extension
Right, if, after such exercise, but prior to the commencement date of the
Extension Term, (i) Tenant fails to timely cure any default by Tenant under this
Lease; or (ii) Tenant has Defaulted 3 or more times during the period from the
date of the exercise of the Extension Right to the date of the commencement of
the Extension Term, whether or not such Defaults are cured.

     40. MISCELLANEOUS.

     (a) NOTICES. All notices or other communications between the parties shall
be in writing and shall be deemed duly given upon delivery or refusal to accept
delivery by the addressee thereof if delivered in person, or upon actual receipt
if delivered by reputable overnight guaranty courier, addressed and sent to the
parties at their addresses set forth above.

<PAGE>

Landlord and Tenant may from time to time by written notice to the other
designate another address for receipt of future notices.

     (b) JOINT AND SEVERAL LIABILITY. If and when included within the term
"Tenant," as used in this instrument, there is more than one person or entity,
each shall be jointly and severally liable for the obligations of Tenant.

     (c) FINANCIAL INFORMATION. Tenant shall furnish Landlord with true and
complete copies of (i) Tenant's most recent unaudited annual financial
statements within 90 days of the end of each of Tenant's fiscal years during the
Term and the audited annual financial statement within 180 days of the end of
Tenant's fiscal years during the Term, (ii) Tenant's most recent unaudited
quarterly financed statements within 45 days of the end of each of Tenant's
fiscal quarters during the Term, (iii) at Landlord's request from time to time,
updated business plans, including cash flow projections and/or pro forma balance
sheets and income statements, all of which shall be treated by Landlord as
confidential information belonging to Tenant, (iv) corporate brochures and/or
profiles prepared by Tenant for prospective investors, and (v) any other
financial information or summaries that Tenant typically provides to its lenders
or shareholders.

     (d) RECORDATION. Neither this Lease nor a memorandum of lease shall be
filed by or on behalf of Tenant in any public record. Landlord may prepare and
file, and upon request by Landlord Tenant will execute, a memorandum of lease.

     (e) INTERPRETATION. The normal rule of construction to the effect that any
ambiguities are to be resolved against the drafting party shall not be employed
in the interpretation of this Lease or any exhibits or amendments hereto. Words
of any gender used in this Lease shall be held and construed to include any
other gender, and words in the singular number shall be held to include the
plural, unless the context otherwise requires. The captions inserted in this
Lease are for convenience only and in no way define, limit or otherwise describe
the scope or intent of this Lease, or any provision hereof, or in any way affect
the interpretation of this Lease.

     (f) NOT BINDING UNTIL EXECUTED. The submission by Landlord to Tenant of
this Lease shall have no binding force or effect, shall not constitute an option
for the leasing of the Premises, nor confer any right or impose any obligations
upon either party until execution of this Lease by both parties.

     (g) LIMITATIONS ON INTEREST. It is expressly the intent of Landlord and
Tenant at all times to comply with applicable law governing the maximum rate or
amount of any interest payable on or in connection with this Lease. If
applicable law is ever judicially interpreted so as to render usurious any
interest called for under this Lease, or contracted for, charged, taken,
reserved, or received with respect to this Lease, then it is Landlord's and
Tenant's express intent that all excess amounts theretofore collected by
Landlord be credited on the applicable obligation (or, if the obligation has
been or would thereby be paid in full, refunded to Tenant), and the provisions
of this Lease immediately shall be deemed reformed and the amounts thereafter
collectible hereunder reduced, without the necessity of the execution of any new
document, so as to comply with the applicable law, but so as to permit the
recovery of the fullest amount otherwise called for hereunder.

<PAGE>

     (h) CHOICE OF LAW. Construction and interpretation of this Lease shall be
governed by the internal laws of the state in which the Premises are located,
excluding any principles of conflicts of laws.

     (i) TIME. Time is of the essence as to the performance of the parties'
obligations under this Lease.

     (j) INCORPORATION BY REFERENCE. All exhibits and addenda attached hereto
are hereby incorporated into this Lease and made a part hereof. If there is any
conflict between such exhibits or addenda and the terms of this Lease, such
exhibits or addenda shall control.

                            [Signature Page Follows)

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Lease as of the
day and year first above written.

                                    TENANT:

                                    t.BREEDERS, INC., a Delaware corporation

                                    By: Signature on File
                                        -------------------------------------
                                    Its: President
                                        -------------------------------------

                                    LANDLORD:

                                    ARE-ONE INNOVATION DRIVE, LLC,
                                    a Delaware limited liability company

                                    By:  AREE-Holdings, L.P., a Delaware limited
                                         partnership, its managing member

                                         By:  ARE-GP Holdings QRS Corp., a
                                              Delaware corporation, its general
                                              partner

                                    By: /s/ Lynne Anne Shapiro
                                        -------------------------------------

                                    Its: General Counsel
                                        -------------------------------------

         [Notary seal]

<PAGE>

                               EXHIBIT B TO LEASE

                             DESCRIPTION OF PROJECT

<PAGE>

                                 QUITCLAIM DEED

     WALDO CORPORATION, a corporation duly established under the laws of
Massachusetts and having a usual place of business at 33 Waldo Street,
Worcester, Worcester County, Massachusetts, as Trustee of Three Biotech Realty
Trust under Declaration of Trust dated September 8, 1995 and recorded with the
Worcester District Registry of Deeds in Book 17323, Page 157, for consideration
paid and in full consideration of $16,500,000 grants to ARE-ONE INNOVATION
DRIVE, LLC, a limited liability company duly, established under the laws of
Delaware and having a usual place of business at 135 N. Los Robles Avenue, Suite
250, Pasadena, Los Angeles County, California

                            WITH QUITCLAIM COVENANTS

     the following two (2) parcels of land:

     PARCEL 1

     The land with the building thereon in Worcester, Worcester County,
Massachusetts consisting of Area A containing 2.7893 acres, more or less, Area B
containing 5.6169 acres, more or less, and a portion of Innovation Drive
containing 17,361 square feet, more or less, all as shown on a plan entitled
"Plan of Property Owned by Worcester Business Development Corporation, Three
Biotech Park, Off Plantation Street, Worcester, Massachusetts" dated January 31,
1990, prepared by Cullinan Engineering Co., Inc. and recorded with the Worcester
District Registry of Deeds (the "Registry") in Plan Book 633, Plan 79 (the
"Parcel I Plan"), bounded and described as follows:

     BEGINNING at the most northerly corner of the Premises at the intersection
of the southerly line 2 of land now or formerly of The Commonwealth of
Massachusetts and the westerly line of other o land now or formerly of Worcester
Business Development Corporation ("WBDC") as shown on the Parcel I Plan;

     THENCE S. 07 DEG. 38' 43" E. one hundred thirty-eight and 71/100 (138.71)
feet by WBDC land and land shown on the Parcel I Plan as Two Biotech Park to a
point;

     THENCE S. 00 DEG. 45' 00" W. two hundred fifty and 45/100 (250.45) feet
by Two Biotech Park to a point;

     THENCE S. 04 DEG. 12' 20" W. one hundred ninety-five and 54/100 (195.54)
feet by Two Biotech Park to a point;

     THENCE S. 04 DEG. 04' 59" W. seventy (70) feet by Two Biotech Park and land
shown on the Parcel I Plan as C.M.M.I.C. Parcel to a point;

     THENCE S. 18 DEG. 32' 25" W. one hundred eighty-seven and 62/100 (187.62)
feet by C.M.M.I.C. Parcel to a point at land shown on the Parcel I Plan as One
Biotech Park;

<PAGE>

     THENCE N. 67 DEG. 02' 30" W. nineteen and 33/100 (19.33) feet by One
Biotech Park to a point;

     THENCE S. 81 DEG. 31' 00" W. eighty (80) feet by One Biotech Park to a
point at other land now or formerly of WBDC;

     THENCE N. 89 DEG. 43' 26" W. one hundred forty and 03/100 (140.03) feet by
land now or formerly of WBDC to a point at the roadway easement, Innovation
Drive, shown on the Parcel I Plan;

     THENCE N. 64 DEG. 42' 20" W. fifty (50) feet across Innovation Drive to a
point;

     THENCE 48 DEG. 20' 06" W. three hundred ninety-six and 74/100 (396.74)
feet by WBDC land to a point at land shown on the Parcel I Plan as B.A.S.F.
Parcel;

     THENCE N. 30 DEG. 42' 12" W. two hundred fifty-five and 04/100 (255.04)
feet by B.A.S.F. Parcel to a point at The Commonwealth of Massachusetts land;

     THENCE N. 63 DEG. 33' 40" E. twenty and 06/100 (20.06) feet to a point;

     THENCE N. 40 DEG. 43' 36" E. two hundred sixteen and 21/100 (216.21) feet
to a point;

     THENCE N. 49 DEG. 56' 15" E. three hundred fifty (350) feet to a point;

     THENCE by a curve to the left having a radius of 225.00 feet and an arc
distance of three hundred thirty-seven and 01/100 (337.01) feet to a point;

     THENCE N. 67 DEG. 21' 00" E. three hundred ninety-nine and 15/100 (399.15)
feet to the point of beginning, the last five courses being by The Commonwealth
of Massachusetts land.

     CONTAINING 8.8048 acres, more or less, according to the Parcel I Plan. Area
A and Area B shown on the Plan are the same parcels shown as Parcel 7B and
Parcels 7A, respectively, on a plan entitled "Amended Definitive Subdivision
Plan for Worcester Business Development Corporation, Belmont Street (Route 9) &
Plantation Street, Worcester, Massachusetts" dated January 3, 1990 prepared by
Maguire Group, Inc. and Cullinan Engineering Co., Inc. recorded at the Registry
in Plan Book 633, Plan 78 ("Amended Subdivision Plan").

     The premises are conveyed subject to and together with the following
rights, easements, benefits and appurtenances:

     1. Easements in common with others to use, for all public way purposes,
Research Drive (shown as "RE-1"), Innovation Drive (shown as "RE-2") and Roadway
Easement 3 (shown as "RE-3") on the Amended Subdivision Plan.

     2. An easement in common with others to use, for all public way purposes,
Easement Areas "A" and "B" which are described in the deed from The Commonwealth
of Massachusetts, acting by and through its Division of Capital Planning and
Operations, to WBDC dated June 13, 1984 and recorded at the Registry in Book
8233, Page 106.

<PAGE>

     3. An easement in common with others to use for all public way purposes,
Easement "C", as shown on the Amended Subdivision Plan.

     4. Rights in common with others to use for their intended purposes those
Utility Easements which service the Premises shown on the Amended Subdivision
Plan.

     5. Provisions of a Declaration of Easement by Worcester Business
Development Corporation dated March 27, 1990 and recorded with the Registry in
Book 12717, Page 3, as modified by an Amendment dated August 24, 1992 and
recorded with the Registry in Book 14471, Page 357.

     6. The provisions of Variance Decision by the Worcester Zoning Board of
Appeals recorded at the Registry in Book 12556, Page 319.

     7. Reservations, restrictions, covenants, conditions, terms and provisions
set forth or referred to in the deed from The Commonwealth of Massachusetts,
acting by and through its Division of Capital Planning and Operations, to WBDC
dated June 13, 1984 and recorded with the Registry in Book 8233, Page 106.

     8. Rights of others in Innovation Drive (shown as "RE-2") on a plan
recorded with the Registry in Plan Book 633, Plan 78 and rights in the areas
shown as "UE-13", "UE-16", UE-18" and "UE-20" on said Plan, all as recited in a
Deed of Easement from WBDC to City of Worcester dated April 30, 1990 and
recorded with the Registry in Book 12860, Page 123.

     9. The grading and drainage easement for the benefit of the land known as
"One Biotech Parcel" shown on a plan recorded with the Registry in Plan Book
550, Plan 12.

     10. Rights reserved by WBDC in its deed to Waldo Corporation, as Trustee of
Three Biotech Realty Trust, to use, maintain, repair, replace, relocate all
existing pipes, lines, manholes and other apparatus for sewer and drainage
purposes, and to grant those rights to others, provided that any relocation will
not interfere with the development or use of the Premises, and any surface which
is disturbed will be restored as near as possible to its original condition, as
recited in the deed from WBDC to Massachusetts Biotechnology Research Institute,
Inc. dated July 20, 1990 and recorded with the Registry in Book 12905, Page 393.

     11. Provisions of a Declaration of Protective Covenants, Conditions and
Restrictions by WBDC dated June 26, 1990 and recorded with the Registry in Book
12860, Page 145.

     12. Order of Taking by the City of Worcester from WBDC to make Innovation
Drive public dated April 13, 1993 and recorded with the Registry in Book 15379,
Page 215.

     13. Rights in areas shown as "UE-22", "UE-23" and "UE-24" on a plan
recorded with the Registry in Plan Book 696, Page 87 granted to the City of
Worcester and The Commonwealth of Massachusetts by the Massachusetts
Biotechnology Research Institute, Inc. in an instrument dated September 22, 1995
and recorded in Book 17343, Page 96.

     14. Security Agreement and Mortgage Deed from Massachusetts Biotechnology
Research Institute, Inc. (as Ground Lessor) and Waldo Corporation, as Trustee of
Three Biotech

<PAGE>

Realty Trust (as Ground Lessee) to Teachers Insurance and Annuity Association of
America for $14,360,000.00 dated December 20, 1995 and recorded with the
Registry in Book 17557, Page 387, with a outstanding balance of $11,297,144.47,
which the Grantee hereby assumes and agrees to pay.

     See deed to Waldo Corporation, as Trustee of Three Biotech Realty Trust,
from Massachusetts Biomedical Research Initiatives, Inc. dated January 6, 1999,
and recorded herewith.

PARCEL II

Parcel of land in The Commonwealth of Massachusetts, County of Worcester, City
of Worcester on the westerly side of Innovation Drive owned by Worcester
Business Development Corporation and shown as Parcel 4 on a plan by Cullinan
Engineering Co., Inc. titled 'Plan of Property -- Worcester, Mass." and dated
July 6, 1998 and recorded with the Worcester District Registry of Deeds in Plan
Book 736, Page 54 ("Parcel II Plan") and bounded and described as follows:

BEGINNING at a point of tangency on the westerly sideline of Innovation Drive at
the most northerly corner of the parcel to be described; said point being N
64 DEG. 42' 20" W and 2.00 feet from a Worcester Highway Bound;

THENCE along the westerly sideline of Innovation Drive the following three (3)
courses:

S 25 DEG. 17' 40" W, a distance of 212.23 feet to a point of curvature;

In a southerly direction by a curve to the left, having a radius of 500.00 feet,
an are distance of 402.55 feet to a point of tangency;

AND S. 20 DEG. 50' 05" E., a distance of 3.29 feet to a point at land now or
formerly of BASF Bioresearch Corp:;

THENCE N. 30 DEG. 42' 12" W along land now or formerly of BASF Bioresearch
Corp., a distance of 375.30 feet to a point at other land now or formerly of
Worcester Business Development Corporation;

THENCE N. 48 DEG. 20' 06" E. along land now or formerly of Worcester Business
Development Corporation, a distance of 396.74 feet to the Point of Beginning;

CONTAINING 1.0508 acres, more or less according to the Parcel II Plan.

Also including the fee interest in that portion of Innovation Drive abutting the
above-described Parcel II, to the center line of Innovation Drive.

The premises are conveyed subject to and together with the following rights,
easements, benefits and appurtenances:

<PAGE>

     1. Easements in common with others to use, for all public way purposes,
Research Drive (shown as "RE-i"), Innovation Drive (shown as "RE-2") and Roadway
Easement 3 (shown as "RE-3") on the Amended Subdivision Plan.

     2. An easement in common with others to use, for all public way purposes,
Easement Areas "A" and "B" which are described in the deed from the The
Commonwealth of Massachusetts, acting by and through its Division of Capital
Planning and Operations, to WBDC dated June 13, 1984 and recorded at the
Registry in Book 8233, Page 106.

     3. An easement in common with others to use for all public way purposes,
Easement "C", as shown on the Amended Subdivision Plan.

     4. Rights in common with others to use for their intended purposes those
Utility Easements which service the Premises shown on the Amended Subdivision
Plan.

     5. Restrictions and other provisions of a deed from The Commonwealth of
Massachusetts to Worcester Business Development Corporation dated June 13, 1984
and recorded with the Registry in Book 8233, Page 106.

     6. Rights of the City of Worcester under a deed of easements from Worcester
Business Development Corporation dated April 30, 1990 and recorded with the
Registry in Book 12860, Page 123.

     7. Provisions of a Declaration of Protective Covenants, Conditions and
Restrictions by Worcester Business Development Corporation dated June 26, 1990
and recorded with the Registry in Book 12860, Page 145.

     8. Rights of others in "Proposed UE-19" shown on plan recorded with the
Registry in Plan Book 633, Plan 78.

     9. Order of Taking from Worcester Business Development Corporation by the
City of Worcester for Innovation Drive recorded with the Registry in Book 15379,
Page 215.

     See deed to Waldo Corporation, as Trustee of Three Biotech Realty Trust,
from Worcester Business Development Corporation dated January 15, 1999 and
recorded herewith.

     The premises conveyed hereby are not all, or substantially all, of the
property of Waldo Corporation, as Trustee of Three Biotech Realty Trust, and
Worcester Business Development Corporation in The Commonwealth of Massachusetts.

     [THIS SPACE INTENTIONALLY LEFT BLANK]

<PAGE>

                               EXHIBIT C TO LEASE
                                [LANDLORD BUILD]

                                   WORK LETTER

     THIS WORK LETTER dated Feb. 24, 2000 (this "Work Letter") is made and
entered into by and between ARE-ONE INNOVATION DRIVE, LLC, a Delaware limited
liability company ("Landlord"), and t.BREEDERS, INC., a Delaware Corporation
("Tenant"), and is attached to and made a part of the Lease dated Feb. 24, 2000
(the "Lease"), by and between Landlord and Tenant. Any initially capitalized
terms used but not defined herein shall have the meanings given them, in the
Lease.

     1. GENERAL REQUIREMENTS

     (a) TENANT'S AUTHORIZED REPRESENTATIVE. Tenant designates Mr. Morey Kraus
("TENANT'S Representative") as the only person authorized to act for Tenant
pursuant to this Work Letter. Landlord shall not be obligated to respond to or
act upon any request, approval, inquiry or other communication ("COMMUNICATION")
from or on behalf of Tenant in connection with this Work Letter unless such
Communication is in writing from Tenant's Representative. Tenant may change
Tenant's Representatives at any time upon not less than 5 business days advance
written notice to Landlord. No period set forth herein for any approval of any
matter by Tenant's Representative shall be extended by reason of any change in
Tenant's Representative. Neither Tenant nor Tenant's Representative shall be
authorized to direct Landlord's contractors in the performance of Landlord's
Work (as hereinafter defined).

     (b) LANDLORD'S AUTHORIZED REPRESENTATIVE. Landlord designates Mr. Tom
Andrews and Mr. Albert Cleef (either such individual acting alone, "Landlord's
Representative") as the only persons authorized to act for Landlord pursuant to
this Work Letter. Tenant shall not be obligated to respond to or act upon any
request, approval, inquiry or other Communication from or on behalf of Landlord
in connection with this Work Letter unless such Communication is in writing from
Landlord's Representative. Landlord may change Landlord's Representatives at any
time upon not less than 5 business days advance written notice to Tenant. No
period set forth herein for any approval of any matter by Landlord's
Representative shall be extended by reason of any change in Landlord's
Representative. Landlord's Representative shall be the sole persons authorized
to direct Landlord's contractors in the performance of Landlord's Work.

     (c) DEVELOPMENT SCHEDULE. The schedule for design and development of the
Tenant Improvements (as defined below), including without limitation the time
periods for delivery of construction documents and performance, shall be in
accordance with the Development Schedule attached hereto as Schedule A, subject
to adjustment as mutually agreed by the parties in writing or as provided in
this Work Letter (the "DEVELOPMENT SCHEDULE").

     (d) ARCHITECTS, CONSULTANTS AND CONTRACTORS. Landlord and Tenant hereby
acknowledge and agree that the architect for the Tenant Improvements shall be
Arch Design, Inc. (the "TI ARCHITECT"), and the general contractor shall be
Richmond Group, Inc., and any subcontractors for the Tenant Improvements shall
be selected by Landlord, subject to Tenant's approval, which approval shall not
be unreasonably withheld, conditioned or delayed.

<PAGE>

     2. TENANT IMPROVEMENTS.

     (a) TENANT IMPROVEMENTS DEFINED. As used herein, "Tenant Improvements"
shall mean all improvements to the Project desired by Tenant of a fixed and
permanent nature as depicted on the TI Construction Drawings (defined below).
Other than the Tenant Improvements and recarpeting and repainting of offices as
shown on the plan attached hereto as Schedule B, Landlord shall not have any
obligation whatsoever with respect to the finishing of the Premises for Tenant's
use and occupancy.

     (b) TENANT'S SPACE PLANS. Landlord and Tenant acknowledge and agree that
the TI Architect schematic drawings and outline specifications (the "TI Design
Drawings") detailing Tenant's requirements for the Tenant Improvements have all
already been submitted by Tenant and approved by Landlord.

     (c) WORKING DRAWINGS. Not later than ten (10) business days following
execution of the Lease, Landlord shall cause the Tl Architect to prepare and
deliver to Tenant for review and comment construction plans, specifications and
drawings for the Tenant Improvements ("TI Construction Drawings"), which TI
Construction Drawings shall be prepared substantially in accordance with the
preliminary plans and specifications for development of the Tenant Improvements
(the "Preliminary TI Plans") which Tenant acknowledges having already reviewed
and approved. Tenant shall be solely responsible for ensuring that the TI
Construction Drawings reflect Tenant's requirements for the Tenant Improvements.
Tenant shall deliver its written comments on the TI Construction Drawings to
Landlord not later than five (5 business days after Tenant's receipt of the
same; provided, however, that Tenant may not disapprove any matter that is
consistent with the Preliminary TI Plans without submitting a Change Request.
Landlord and the TI Architect shall consider all such comments in good faith and
shall, within five (5) business days after receipt, notify Tenant how Landlord
proposes to respond to such comments, but Tenant's review rights pursuant to the
foregoing sentence shall not delay the design or construction schedule for the
Tenant Improvements. Any disputes in connection with such comments shall be
resolved in accordance with Section 2(d) hereof. Provided that the design
reflected in the TI Construction Drawings is consistent with the Preliminary TI
Plans approved by Tenant, Tenant shall approve the TI Construction Drawings
submitted by Landlord, unless Tenant submits a Change Request. Once approved by
Tenant, subject to the provisions of Section 2(d) below, Landlord shall not
materially modify the TI Construction Drawings except as may be reasonably
required in connection with the issuance of the TI Permit.

     (d) APPROVAL AND COMPLETION. Upon any dispute regarding the design of the
Tenant Improvements, which is not settled within five (5) business days after
notice of such dispute is delivered by one party to the other, Tenant shall make
the final decision regarding the design of the Tenant Improvements, provided
Tenant acts reasonably and such final decision is either consistent with or a
compromise between Landlord's and Tenant's positions with respect to such
dispute, provided further that all costs and expenses resulting from any such
decision by Tenant shall be payable out of the TI Fund, as defined in Section
5(d) below. Any changes to the Tl Construction Drawings following Landlord's and
Tenant's approval of same requested by Tenant shall be processed as provided in
Section 4 hereof.

<PAGE>

     3. PERFORMANCE OF LANDLORD'S WORK.

     (a) DEFINITION OF LANDLORD'S WORK. As used herein, "Landlord's Work" shall
mean the work of constructing the Tenant Improvements.

     (b) COMMENCEMENT AND PERMITTING OF LANDLORD'S WORK. Landlord shall commence
construction of the Tenant Improvements upon obtaining a building permit (the
"TI Permit") authorizing the construction of the Tenant Improvements consistent
with the TI Construction Drawings approved by Tenant. The cost of obtaining the
TI Permit shall be payable from the TI Fund. Tenant shall assist Landlord in
obtaining the TI Permit. If any Governmental Authority having jurisdiction over
the construction of Landlord's Work or any portion thereof shall impose terms or
conditions upon the construction thereof which: (i) are inconsistent with
Landlord's obligations hereunder, (ii) increase the cost of constructing
Landlord's Work, or (iii) will materially delay the construction of Landlord's
Work, Landlord and Tenant shall reasonably and in good faith seek means by which
to mitigate or eliminate any such adverse terms and conditions.

     (c) COMPLETION OF LANDLORD'S WORK. Landlord shall substantially complete or
cause to be substantially completed Landlord's Work in a good and workmanlike
manner using materials reasonably acceptable to the TI Architect, in accordance
with the TI Permit subject to Minor Variations and normal "punch list" items of
a non-material nature which do not interfere with the use of the Premises
("Substantial Completion"). Upon the Substantial Completion of Landlord's Work,
Landlord shall require the TI Architect and the general contractor to execute
and deliver, for the benefit of Tenant and Landlord, a Certificate of
Substantial Completion in the form of the American Institute of Architects
document G704. For purposes of this Work Letter, "Minor Variations" shall mean
any modifications reasonably required: (i) to comply with all applicable Legal
Requirements and for to obtain or to comply with any required permit (including
the TI Permit); (ii) to comply with any request by the Tenant for modifications
to Landlord's Work; (iii) to comport with good design, engineering, and
construction practices which are not material; or (iv) to make reasonable
adjustments for field deviations or conditions encountered during the
construction of Landlord's Work.

     (d) SELECTION OF MATERIALS, ETC. Where more than one type of material or
structure is indicated on the Tl Construction Drawings approved by Landlord and
Tenant, the option will be within Landlord's sole discretion. As to all building
materials and equipment which Landlord is obligated to supply under this Work
Letter, Landlord shall select the manufacturer thereof in its sole discretion.

     (e) ACCEPTANCE OF LANDLORD'S WORK. When Landlord's Work is Substantially
Complete, subject to the remaining terms and provisions of this Section 3(e),
Tenant shall accept such work. Tenant's acceptance of Landlord's Work shall not
constitute a waiver of: (i) any warranty with respect to workmanship (including
installation of equipment) or material (exclusive of equipment provided directly
by manufacturers) (ii) any non-compliance of Landlord's Work with Code, or (iii)
any claim that Landlord's Work was not completed substantially in accordance
with the TI Construction Drawings (subject to Minor Variations and such other
changes as are permitted hereunder) (collectively, a "Construction

<PAGE>

Defect"). Tenant shall have one (1) year after Substantial Completion within
which to notify Landlord of any such Construction Defect discovered by Tenant,
and Landlord shall use reasonable efforts to remedy or cause the responsible
contractor to remedy any such Construction Defect within thirty (30) days
thereafter. Notwithstanding the foregoing, Landlord shall not be in default
under the Lease if the applicable contractor, despite Landlord's reasonable
efforts, fails to remedy such Construction Defect within such thirty (30) day
period, in which case Landlord shall have no further obligation with respect to
such Construction Defect other than to cooperate, at no cost to Landlord, with
Tenant should Tenant elect to pursue a claim against such contractor, provided
that Tenant indemnifies and holds Landlord harmless from and against any
liability, loss, cost damage or expense in connection with any such claim.

     Upon written request from Tenant, Landlord agrees, at no cost to Landlord
and subject to the indemnity and hold harmless in the preceding sentence, to
execute such documents as may be reasonably requested by Tenant in order that
Tenant may pursue a claim directly or, if Landlord consents, in Landlord's name
against the responsible contractor in connection with a Construction Defect.
Tenant shall be entitled to receive the benefit of all construction warranties
and manufacturer's equipment warranties relating to equipment installed in the
Premises. If requested by Tenant, Landlord shall attempt to obtain extended
warranties from manufacturers and suppliers of such equipment, but the cost of
any such extended warranties shall be borne solely out of the TI Fund. Landlord
shall diligently pursue any claims arising out of latent defects in the
Building. Landlord shall promptly undertake and complete, or cause to be
completed, all punch list items.

     (f) RENT INCREASE DATE. The Rent Increase Date shall occur when Landlord's
Work has been Substantially Completed, except to the extent that completion of
Landlord's Work shall have been actually delayed by any one or more of the
following causes (a "Tenant Delay"):

         (i) Tenant's Representative was not available to give or receive any
     Communication or to take any other action required to be taken by Tenant
     hereunder;

         (ii) Tenants request for Change Requests whether or not any such Change
     Requests are actually performed;

         (iii) Construction of any Change Requests;

         (iv) Tenant's request for materials, finishes or installations
     requiring unusually long lead times;

         (v) Tenant's delay in reviewing, revising or approving plans and
     specifications beyond the periods set forth herein;

         (vi) Tenant's delay in providing information critical to the normal
     progression of the Project. Tenant shall provide such information as soon
     as reasonably possible, but in no event longer than one week after receipt
     of any request for such information from Landlord;

         (vii) Tenant's delay in making payments to Landlord for Excess TI
     Costs; or

<PAGE>

         (viii) Any other act or omission by Tenant, its agents, contractors or
     persons employed by any of such persons.

         If the Rent Increase Date is delayed for any of the foregoing reasons,
     then Landlord shall cause the TI Architect to certify the date on which the
     Tenant Improvements would have been completed but for such Tenant Delay and
     such certified date shall be the Rent Increase Date under the Lease.

     4. CHANGES. Any changes requested by Tenant to the Tenant Improvements
after the delivery and approval by Landlord of the TI Design Drawings, shall be
requested and instituted in accordance with the provisions of this Section 4 and
shall be subject to the written approval of Landlord and the TI Architect, such
approval not to be unreasonably withheld, conditioned or delayed.

     (a) TENANT'S RIGHT TO REQUEST CHANGES. If Tenant shall request changes to
Landlord's Work ("CHANGES"), Tenant shall request such Changes by notifying
Landlord in writing in substantially the same form as the AlA standard change
order form (a "Change Major Construction - Landlord Build, One Innovation
Drive/t.Breeders, Inc. Page 5 Request"), which Change Request shall detail the
nature and extent of any such Change. Such Change Request must be signed by
Tenant's Representative. Landlord shall, before proceeding with any Change, use
its best efforts to respond to Tenant as soon as is reasonably possible with an
estimate of: (i) the time it will take, and (ii) the architectural and
engineering fees and costs which will be incurred, to analyze such Change
Request (which costs shall be paid from the TI Fund to the extent actually
incurred, whether or not such change is implemented). Landlord shall thereafter
submit to Tenant in writing, within five (5)) business days of receipt of the
Change Request (or such longer period of time as is reasonably required
depending on the extent of the Change Request), an analysis of the additional
cost or savings involved, including, without limitation architectural and
engineering costs and the period of time, if any, that the Change will extend
the date on which Landlord's Work will be Substantially Complete. Any such delay
in the completion of Landlord's Work caused by a Change, including any
suspension of Landlord's Work while any such Change is being evaluated and/or
designed, shall be a Tenant Delay.

     (b) IMPLEMENTATION OF CHANGES. If Tenant: (i) approves in writing the cost
or savings and the estimated extension in the time for completion of Landlord's
Work, if any, and (ii) deposits with Landlord any Excess TI Costs (as defined
below) required in connection with such Change, Landlord shall cause the
approved Change to be instituted. Notwithstanding any approval or disapproval by
Tenant of any estimate of the delay caused by such proposed Change, the TI
Architect's determination of the Tenant Delay in connection with such Change
shall be final and binding on Landlord and Tenant.

     5. COSTS.

     (a) BUDGET FOR TENANT IMPROVEMENTS. Before the commencement of construction
of the Tenant Improvements, Landlord shall obtain a detailed breakdown, by
trade, of the costs incurred or which will be incurred, in connection with the
design and construction of Tenant's Work (the "Budget"). The Budget shall be
based upon the TI Construction Drawings approved by Tenant and shall include a
payment to Landlord, of administrative rent equal ("Administrative

<PAGE>

Rent") to 5% of the TI Costs (as hereinafter defined) for monitoring and
inspecting the construction of Tenant's Work, which sum shall be payable from
the TI Fund. Such Administrative Rent shall include, without limitation, all
out-of-pocket costs, expenses and fees incurred by or on behalf of Landlord
arising from, out of, or in connection with, such monitoring of the construction
of the Tenant's Improvements, and shall be payable out of the TI Fund. If the
Budget is greater than the TI Allowance, Tenant shall deposit with Landlord the
difference, in cash, prior to the commencement of construction of the Tenant
Improvements, for disbursement by Landlord as described in Section 5(d).

     (b) TI ALLOWANCE. Landlord shall provide to Tenant a tenant improvement
allowance ("TI Allowance") of $400,000. The TI Allowance shall be disbursed in
accordance with this Work Letter.

     (c) COSTS INCLUDABLE IN TI FUND. The TI Fund shall be used solely for the
payment of design and construction costs in connection with the construction of
the Tenant Improvements, including, without limitation, the cost of preparing
the Tl Design Drawings, the Preliminary TI Plans, and the TI Construction
Drawings, all costs set forth in the Budget, including Landlord's Administrative
Rent, costs resulting from Tenant Delays and the cost of Changes (collectively,
"TI Costs"). Notwithstanding anything to the contrary contained herein, the TI
Fund shall not be used to purchase any furniture, personal property or other
non-building system materials or equipment, including, but not be limited to,
biological safety cabinets and other scientific equipment not incorporated into
the Improvements.

     (d) EXCESS TI COSTS. It is understood and agreed that Landlord is under no
obligation to bear any portion of the cost of any of the Tenant Improvements
except to the extent of the TI Allowance. If at any time and from time-to-time,
the remaining TI Costs under the Budget exceed the remaining unexpended TI
Allowance, Tenant shall deposit with Landlord, as a condition--precedent to
Landlord's obligation to complete the Tenant Improvements, 100% of the then
current TI Cost in excess of the remaining TI Allowance ("Excess TI Costs"). If
Tenant fails to deposit, or is late in depositing, any Excess TI Costs amount
with Landlord, Landlord shall have all of the rights and remedies set forth in
the Lease for nonpayment of Rent (including, but not limited to, the right to
interest at the Default Rate and the right to assess a late charge), and for
purposes of any litigation instituted with regard to such amounts the, same will
be considered Rent, Such deposit of Excess TI Costs, together with the remaining
11 Allowance, is herein referred to as the "Tl Fund". Funds so deposited by
Tenant shall be the first thereafter disbursed to pay TI Costs. Notwithstanding
anything to the contrary set forth in this Section 5(d), Tenant shall be fully
and solely liable for TI Costs and the cost of Minor Variations in excess of the
TI Allowance. If upon Substantial Completion of the Tenant Improvements and the
payment of all sums due in connection therewith there remains any undisbursed Ti
Fund, Tenant shall be entitled to such undisbursed TI Fund solely to the extent
of any Excess TI Costs deposit Tenant has actually made with Landlord.

     6. TENANT ACCESS. Entry by Tenant into the Premises shall comply with all
established safety practices of Landlord's contractor and Landlord until
completion of Landlord's Work and acceptance thereof by Tenant. Neither Tenant
nor its employees, consultants, agents, contractors, and suppliers shall
interfere with the performance of Landlord's Work, nor with any inspections or
issuance of final approvals by the City of Worcester, and upon

<PAGE>

any such interference, Landlord shall have the right to exclude Tenant and
Tenant's employees, consultants, contractors and agents from the Premises and
the Building until Substantial Completion of Landlord's Work. Tenant shall
indemnify and hold Landlord harmless from any loss of or damage to Tenant
property, completed work, fixtures, equipment, materials or merchandise, and
from liability for death of, or injury to, any person, caused by the willful
misconduct or negligence of Tenant or its agents.

     7. NOTIFICATION OF DELAYS. Not less than once each calendar month from the
date of this Work Letter through the Term Commencement Date, Landlord shall
deliver to Tenant written notification of the number of days during the
immediately preceding calendar month Landlord's performance under this Work
Letter or the Lease was delayed as a result of Tenant Delays or delays arising
by reason of any Force Majeure as defined in Section 34 of the Lease (a "Force
Majeure Delay"), which written notification shall also include a description of
the nature of such Tenant Delay or Force Majeure Delay.

     8. MISCELLANEOUS.

     (a) CONSENTS. Whenever consent or approval of either party is required
under this Work Letter, that party shall not unreasonably withhold, condition or
delay such consent or approval, except as may be expressly set forth herein to
the contrary.

     (b) MODIFICATION. No modification, waiver or amendment of this Work
Agreement or of any of its conditions or provisions shall be binding upon
Landlord or Tenant unless in writing signed by Landlord and Tenant.

     (c) COUNTERPARTS. This Work Letter may be executed in any number of
counterparts but all counterparts taken together shall constitute a single
document.

     (d) GOVERNING LAW. This Work Letter shall be governed by, construed and
enforced in accordance with the internal laws of the state in which the Premises
are located, without regard to choice of law principles of such State.

     (e) TIME OF THE ESSENCE. Time is of the essence of this Work Agreement and
of each and all provisions thereof.

     (f) DEFAULT. Notwithstanding anything set forth herein or in the Lease to
the contrary, Landlord shall not have any obligation to perform any work
hereunder or to fund any portion of the TI Fund during any period Tenant is in
Default under the Lease.

     (g) SEVERABILITY. If any term or provision of this Work Letter is declared
invalid or unenforceable, the remainder of this Work Letter shall not be
affected by such determination and shall continue to be valid and enforceable.

     (h) MERGER. All understandings and agreements, oral or written, heretofore
made between the parties hereto and relating to Landlord's Work are merged in
this Work Letter, which alone (but inclusive of provisions of the Lease
incorporated herein and the final approved constructions drawings and
specifications prepared pursuant hereto) fully and completely

<PAGE>

expresses the agreement between Landlord and Tenant with regard to the matters
set forth in this Work Letter.

     (i) ENTIRE AGREEMENT. This Work Letter is made as a part of and pursuant to
the Lease and, together with the Lease, constitutes the entire agreement of the
parties with respect to the subject matter hereof. This Work Letter is subject
to all of the terms and limitation set forth in the Lease, and neither party
shall have any rights or remedies under this Work Letter separate and apart from
their respective remedies pursuant to the Lease.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Work Letter to
be effective on the date first above written.

                                    TENANT:

                                    t.BREEDERS, INC.,
                                    a Delaware corporation

                                    By: Signature on File
                                        -------------------------------------
                                    Its: President
                                        -------------------------------------

                                    LANDLORD:

                                    ARE-ONE INNOVATION DRIVE, LLC,
                                    a Delaware limited liability company

                                    By:  AREE-Holdings, L.P., a Delaware limited
                                         partnership, its managing member

                                    By:  ARE-GP Holdings QRS Corp., a
                                         Delaware corporation, its general
                                         partner

                                    By: /s/ Lynne Anne Shapiro
                                        -------------------------------------
                                    Its: General Counsel
                                        -------------------------------------

<PAGE>

                            SCHEDULE A TO WORK LETTER

                              DEVELOPMENT SCHEDULE
<Table>
<Caption>
         EVENT                                                  DATE
                                                                2/24/00
         <S>                                                    <C>
         Execution of lease

         Naming of Tenant's Representatives                     completed

         Delivery of TI Construction Drawings                   completed

         Commence construction of Tenant Improvements           within 5 days after
                                                                Commencement Date

         Substantial Completion of Tenant Improvements          within 90 days after
                                                                Commencement Date
</Table>

<PAGE>

                            SCHEDULE B TO WORK LETTER

<PAGE>

                            Exhibit A to Work Letter

                                 tBreeders, Inc.

                        List of TI Construction Drawings

<Table>
<S>      <C>                         <C>                        <C>                        <C>
AO       Cover Sheet                 Archdesign, Inc.           #6 Issued for Permit       12-21-99

Dl       Demolition Floor Plan       Archdesign, Inc.           #6 Issued for Permit       12-21-99

Al       First Floor Plan            Archdesign, Inc.           #6 Issued for Permit       12-21-99

A2       Reflected Ceiling Plan      Archdesign, Inc.           #6 Issued for Permit       12-21-99

A3       Schedules                   Archdesign, Inc.           #6 Issued for Permit       12-21-99

FP1      Fire Protection Plan        Noremac Sprinkler          #1 Permit Drawings         12-20-99

P-1      First Floor Plan            NSMC                       #1 Issued for Permit       12-15-99

M1       First Floor HVAC Plan       Environmental Systems      #2 Permit Issue            12-20-99

M2       Plans & Schedules           Environmental Systems      #2 Permit Issue            12-20-99

El       First Floor Lighting        Shepard Engineering        #5 Design Development      12-06-99
</Table>

<PAGE>

                               EXHIBIT D TO LEASE

                       ACKNOWLEDGMENT OF COMMENCEMENT DATE

     This ACKNOWLEDGMENT OF COMMENCEMENT DATE is made this ____ day of
__________, between ARE-ONE INNOVATION DRIVE, LLC, a Delaware limited liability
company ("Landlord"), and t.BREEDERS, INC., a Delaware corporation ("TENANT"),
and is attached to and made a part of the Lease dated ___________, (the
"LEASE"), by and between Landlord and Tenant. Any initially capitalized terms
used but not defined herein shall have the meanings given them in the Lease.

     Landlord and Tenant hereby acknowledge and agree, for all purposes of the
Lease, that the Commencement Date of the Base Term of the Lease is
______________, and the termination date of the Base Term of the Lease shall be
midnight on ____________, ______

     IN WITNESS WHEREOF, Landlord and Tenant have executed this ACKNOWLEDGMENT
OF COMMENCEMENT DATE to be effective on the date first above written.

                                     TENANT:

                                     t. BREEDERS, INC.,
                                     a Delaware corporation

                                     By:
                                        ---------------------------------------
                                     Its:
                                         --------------------------------------

                                     LANDLORD:

                                     ARE-ONE INNOVATION DRIVE, LLC,
                                     a Delaware limited liability company

                                     By: AREE-Holdings, L.P.,
                                         a Delaware limited partnership,
                                         its managing member

                                     By: ARE-GP Holdings QRS Corp.,
                                         a Delaware corporation, its general
                                         partner

                                         By:
                                            --------------------
                                         Its:
                                             -------------------

<PAGE>

                               EXHIBIT E TO LEASE

                              RULES AND REGULATIONS

     1. The sidewalk, entries, and driveways of the Project shall not be
obstructed by Tenant, or its agents, or used by them for any purpose other than
ingress and egress to and from the Premises.

     2. Tenant shall not place any objects, including antennas, outdoor
furniture, etc., in the parking areas, landscaped areas or other areas outside
of its Premises, or on the roof of the Project.

     3. Except for seeing-eye dogs, no animals shall be allowed in the offices,
halls, or corridors in the Project.

     4. Tenant shall not disturb the occupants of the Project or adjoining
buildings by the use of any radio or musical instrument or by the making of loud
or improper noises.

     5. If Tenant desires telegraphic, telephonic or other electric connections
in the Premises, Landlord or its agent will direct the electrician as to where
and how the wires may be introduced; and, without such direction, no boring or
cutting of wires will be permitted. Any such installation or connection shall be
made at Tenant's expense.

     6. Tenant shall not install or operate any steam or gas engine or boiler,
or other mechanical apparatus in the Premises, except as specifically approved
in the Lease. The use of oil, gas or inflammable liquids for heating, lighting
or any other purpose is expressly prohibited. Explosives or other articles
deemed extra hazardous shall not be brought into the Project.

     7. Parking any type of recreational vehicles is specifically prohibited on
or about the Project. Except for the overnight parking of operative vehicles, no
vehicle of any type shall be stored in the parking areas at any time. In the
event that a vehicle is disabled, it shall be removed within 48 hours. There
shall be no "For Sale" or other advertising signs on or about any parked
vehicle. All vehicles shall be parked in the designated parking areas in
conformity with all signs and other markings. All parking will be open parking,
and no reserved parking, numbering or lettering of individual spaces will be
permitted except as specified by Landlord.

     8. Tenant shall maintain the Premises free from rodents, insects and other
pests.

     9. Landlord reserves the right to exclude or expel from the Project any
person who, in the judgment of Landlord, is intoxicated or under the influence
of liquor or drugs or who shall in any manner do any act in violation of the
Rules and Regulations of the Project.

     10. Tenant shall not cause any unnecessary labor by reason of Tenant's
carelessness or indifference in the preservation of good order and cleanliness.
Landlord shall not be responsible to Tenant for any loss of property on the
Premises, however occurring, or for any damage done to the effects of Tenant by
the janitors or any other employee or person.

<PAGE>

     11. Tenant shall give Landlord prompt notice of any defects in the water,
lawn sprinkler, sewage, gas pipes, electrical lights and fixtures, heating
apparatus, or any other service equipment affecting the Premises.

     12. Tenant shall not permit storage outside the Premises, including without
limitation, outside storage of trucks and other vehicles, or dumping of waste or
refuse or permit any harmful materials to be placed in any drainage system or
sanitary system in or about the Premises.

     13. All moveable trash receptacles provided by the trash disposal firm for
the Premises must be kept in the trash enclosure areas, if any, provided for
that purpose.

     14. No auction, public or private, will be permitted on the Premises or the
Project.

     15. No awnings shall be placed over the windows in the Premises except with
the prior written consent of Landlord.

     16. The Premises shall not be used for lodging, sleeping or cooking or for
any immoral or illegal purposes or for any purpose other than that specified in
the Lease. No gaming devices shall be operated in the Premises.

     17. Tenant shall ascertain from Landlord the maximum amount of electrical
current which can safely be used in the Premises, taking into account the
capacity of the electrical wiring in the Project and the Premises and the needs
of other tenants, and shall not use more than such safe capacity. Landlord's
consent to the installation of electric equipment shall not relieve Tenant from
the obligation not to use more electricity than such safe capacity.

     18. Tenant assumes full responsibility for protecting the Premises from
theft, robbery and pilferage.

     19. Tenant shall not install or operate on the Premises any machinery or
mechanical devices of a nature not directly related to Tenant's ordinary use of
the Premises and shall keep all such machinery free of vibration, noise and air
waves which may be transmitted beyond the Premises.

<PAGE>

                               EXHIBIT F TO LEASE

                           TENANT'S PERSONAL PROPERTY

                                   [ATTACHED]

<PAGE>

                                    Exhibit F

                       List of Tenant's Personal Property

All Office Desks, Chairs, File Cabinets, Bookcases
All demountable Office Partition Systems
All freestanding Shelving Units and Systems
All Office Equipment, Computers, Typewriters, Phones
All Cork Boards, Chalk Boards, Bulletin Boards
All Office Supplies
All Laboratory Supplies
All Benchtop and portable Laboratory Equipment
All Laboratory Refrigerators, Freezers, Incubators, Biological Safety Cabinets,
Centrifuges, Balances, Ovens, Ice
Makers, and other laboratory equipment not integrally attached to the building
or building systems.
All Autoclaves, Glassware Washers, Glassware Dryers
All freestanding, non-attached Storage Cabinets, File Cabinets, Shelving Units

<PAGE>

                               EXHIBIT G TO LEASE

                              ESTOPPEL CERTIFICATE

     THIS TENANT ESTOPPEL CERTIFICATE ("CERTIFICATE"), dated as of _______, is
executed by _________________ ("TENANT") in favor of [BUYER], a
________________________________ together with its nominees, designees and
assigns (collectively, "Buyer"), and in favor of _____________, together with
its nominees, designees and assigns (collectively, "LENDER").

                                    RECITALS

     A. Buyer and ___________ ("Landlord"), have entered into that certain
Purchase and Sale Agreement and Joint Escrow Instructions, dated as of
_________, 19_ (the "PURCHASE AGREEMENT"), whereby Buyer has agreed to purchase,
among other things, the improved real property located in the City of _________,
County of _________, State of _________ more particularly described on Exhibit A
attached to the Purchase Agreement (the "PROPERTY").

     B. Tenant and Landlord have entered into that certain Lease Agreement,
dated as of ___________ (together with all amendments, modifications,
supplements, guarantees and restatements thereof, the "LEASE"), for a portion of
the Property.

     C. Pursuant to the Lease, Tenant has agreed that upon the request of
Landlord, Tenant would execute and deliver an estoppel certificate certifying
the status of the Lease.

     D. In connection with the Purchase Agreement, Landlord has requested that
Tenant execute this Certificate with an understanding that Lender will rely on
the representations and agreements below in granting to Buyer a loan.

     NOW, THEREFORE, Tenant certifies, warrants, and represents to Buyer and
Lender as follows:

     1. LEASE. Attached hereto as EXHIBIT B is a true, correct and complete copy
of the Lease, including the following amendments, modifications,
supplements, guarantees and restatements thereof, which together represent all
of the amendments, modifications, supplements, guarantees and restatements
thereof:

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
(If none, please state "None.")

     2. PREMISES. Pursuant to the Lease, Tenant leases those certain premises
(the "Premises") consisting of approximately _______________ rentable square
feet within the Property, as more particularly described in the Lease. In
addition, pursuant to the terms of the Lease, Tenant has the [non-exclusive]
right to use (_____ parking spaces/the parking area] located on the Property
during the term of the Lease. (Cross-out the preceding sentence or portions
thereof if inapplicable.]

<PAGE>

     3. FULL FORCE OF LEASE. The Lease has been duly authorized, executed and
delivered by Tenant, is in full force and effect, has not been terminated, and
constitutes a legally valid instrument, binding and enforceable against Tenant
in accordance with its terms, subject only to applicable limitations imposed by
laws relating to bankruptcy and creditor's rights.

     4. COMPLETE AGREEMENT. The Lease constitutes the complete agreement between
Landlord and Tenant for the Premises and the Property, and except as modified by
the Lease amendments noted above (if any), has not been modified, altered or
amended.

     5. ACCEPTANCE OF PREMISES. Tenant has accepted possession and is currently
occupying the Premises;

 6. LEASE TERM. The term of the Lease commenced on ____________ and ends on
_______________ subject to the following options to extend:____________________
_______________________________________________________________________________
_____________________________
(If none, please state "None.")

     7. PURCHASE RIGHTS. Tenant has no option, right of first refusal, right of
first offer, or other right to acquire or purchase all or any portion of the
Premises or all or any portion of, or interest in, the Property, except as
follows: ______________________________________________________________________
_______________________________________________________________________________
_____________________________
(If none, please state "None.")

     8. RIGHTS OF TENANT. Except as expressly stated in this Certificate,
Tenant:

          (a) has no right to renew or extend the term of the Lease;

          (b) has no option or other right to purchase all or any part of the
Premises or all or any part of the Property;

          (c) has no right, title, or interest in the Premises, other than as
Tenant under the Lease.

     9. RENT.

          (a) The obligation to pay rent under the Lease commenced on___________
The rent under the Lease is current, and Tenant is not in default in the
performance of any of its obligations under the Lease.

          (b) Tenant is currently paying base rent under the Lease in the amount
of $__________ per month. Tenant has not received and is not presently entitled
to any abatement, refunds, rebates, concessions or forgiveness of rent or other
charges, free rent, partial rent, or credits, offsets or reductions in rent,
except as follows: ___________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
__________________________. (If none, please state "None.")

<PAGE>

     (c) Tenant's estimated share of operating expenses, common area charges,
insurance, real estate taxes and administrative and overhead expenses is % and
is currently being paid at the rate of $__________ per month, payable to:
__________

     (d) There are no existing defenses or offsets against rent due or to become
due under the terms of the Lease, and, to the best of Tenant's knowledge, there
presently is no default or other wrongful act or omission by Landlord under the
Lease or otherwise in connection with Tenant's occupancy of the Premises, nor is
there a state of facts which with the passage of time or the giving of notice or
both could ripen into a default on the part of Tenant, or to the best knowledge
of Tenant, could ripen into a default on the part of Landlord under the Lease,
except as follows:___________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
________________________.(If none, please state "None.")

     10. SECURITY DEPOSIT. The amount of Tenant's security deposit held by
Landlord under the Lease is $___________________.

     11. PREPAID RENT. The amount of prepaid rent, separate from the security
deposit, is ___________ covering the period from _______ to _______.

     12. INSURANCE. All insurance, if any, required to be maintained by Tenant
under the Lease is presently in effect.

     13. PENDING ACTIONS. There is not pending or, to the knowledge of Tenant,
threatened against or contemplated by the Tenant, any petition in bankruptcy,
whether voluntary or otherwise, any assignment for the benefit of creditors, or
any petition seeking reorganization or arrangement under the federal bankruptcy
laws or those of any state.

     14. TENANT IMPROVEMENTS. As of the date of this Certificate, to the best of
Tenant's knowledge, Landlord has performed all obligations required of Landlord
pursuant to the Lease; no offsets, counterclaims, or defenses of Tenant under
the Lease exist against Landlord; and, to the best of Tenant's knowledge, no
events have occurred that, with the passage of time or the giving of notice,
would constitute a basis for offsets, counterclaims, or defenses against
Landlord, except as follows:__________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
________________________. (If none, please state "None.")

     15. ASSIGNMENTS BY LANDLORD. Tenant has received no notice of any
assignment, hypothecation or pledge of the Lease or rentals under the Lease by
Landlord. Tenant hereby consents to an assignment of the Lease and rents to be
executed by Landlord to Buyer or Lender in connection with the Loan and
acknowledges that said assignment does not violate the provisions of the Lease.
Tenant acknowledges that the interest of the Landlord under the Lease is to be
assigned to Buyer or Lender solely as security for the purposes specified in
said assignment and Buyer or Lender shall have no duty, liability or obligation
whatsoever under the Lease or any extension or renewal thereof, either by virtue
of said assignment or by any subsequent receipt or collection of rents
thereunder, unless Buyer or Lender shall specifically

<PAGE>

undertake such liability in writing. Tenant agrees that upon receipt of a
written notice from Buyer or Lender of a default by Landlord under the Loan,
Tenant will thereafter pay rent to Buyer or Lender in accordance with the terms
of the Lease provided that Tenant will have the right to rely on such notice
without independent inquiry as to its accuracy.

     16. ASSIGNMENTS BY TENANT. Tenant has not sublet or assigned the Premises
or the Lease or any portion thereof to any sublessee or assignee. No one except
Tenant and its employees will occupy the Premises. The address for notices to be
 .sent to Tenant is as set forth in the Lease.

     17. ENVIRONMENTAL MATTERS. The operation and use of the Premises does not
involve the generation, treatment, storage, disposal or release into the
environment of any hazardous materials, regulated materials and/or solid waste,
except those used in the ordinary course of operating for the Permitted Use, as
defined in the Lease, or otherwise used in accordance with all applicable laws.

     18. SUCCESSION OF INTEREST. Tenant agrees that, in the event Buyer or
Lender succeeds to the interest of Landlord under the Lease:

               (a) Buyer or Lender shall not be liable for any act or omission
          of any prior landlord (including Landlord);

               (b) Buyer or Lender shall not be liable for the return of any
          security deposit;

               (c) Buyer or Lender shall not be bound by any rent or additional
          rent which Tenant might have prepaid under the Lease for more than the
          current month;

               (d) Buyer or Lender shall not be bound by any amendments or
          modifications of the Lease after the date hereof made without prior
          consent of Buyer or Lender;

               (e) Buyer or Lender shall not be subject to any offsets or
          defenses which Tenant might have against any prior landlord (including
          Landlord); or

               (f) Buyer or Lender shall not be liable under the Lease to Tenant
          for the performance of Landlord's obligations under the Lease beyond
          Buyer or Lender's interest in the Property.

     19. NOTICE OF DEFAULT. Tenant agrees to give Buyer and Lender a copy of any
notice of default under the Lease served upon Landlord at the same time as such
notice is given to Landlord. Tenant further agrees that if Landlord shall fail
to cure such default within the applicable grace period, if any, provided in the
Lease, then Buyer or Lender shall have an additional 60 days within which to
cure such default, or if such default cannot be cured within such 60-day period,
such 60-day period shall be extended so long as Buyer or Lender has commenced
and is diligently pursuing the remedies necessary to cure such default
(including, but

<PAGE>

not limited to, commencement of foreclosure proceedings, if necessary to effect
such cure, in which event the Lease shall not be terminated while such remedies
are being pursued.

     Tenant makes this Certificate with the knowledge that it will be relied
upon by Buyer and Lender in agreeing to purchase the Property.

     Tenant has executed this Certificate as of the date first written above by
the person named below, who is duly authorized to do so.

     TENANT:
                                         ---------------------------------------
                                         a
                                          -------------------------------------

                                         By:
                                             ----------------------------------
                                             Name:
                                                  -----------------------
                                             Its:
                                                 ---------------------------

<PAGE>

                        EXHIBIT A TO ESTOPPEL CERTIFICATE

                                LEGAL DESCRIPTION

<PAGE>

                        EXHIBIT B TO ESTOPPEL CERTIFICATE

                                  COPY OF LEASE

<PAGE>

                               EXHIBIT H TO LEASE

                       SUBORDINATION, NON-DISTURBANCE AND
                              ATTORNMENT AGREEMENT

     THIS SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT is made and
entered into as of _________, ___, _____ ("Agreement"), by and between
________________ a ________________ together with its nominees, designees and
assigns (collectively, "Landlord"), ________________________, a _______________
("Tenant"), and __________________, a _____________("Mortgagee").

     WHEREAS, Mortgagee is making a loan to Landlord and others evidenced by a
certain promissory note ("Note"), and secured by, among other things, a deed of
trust/mortgage to be recorded prior hereto in the public records of the City of
_________, County of __________, State of _______ ("Mortgage") constituting a
lien upon the real property described in Exhibit A hereto (the "Real Property");
and

     WHEREAS, ____________________________ and Tenant have entered into a Lease
Agreement dated as of ________________, _____ ("Lease"), for certain leased
premises encompassing _____________________________________ located in
_____________, containing approximately _________________________ net square
feet (hereinafter collectively referred to as "Premises"); and

     WHEREAS, subject to the provisions hereof, the Lease is subordinate to the
Mortgage and to the right, title, and interests of Mortgagee thereto and
thereunder; and

     WHEREAS, Mortgagee wishes to obtain from Tenant certain assurances that
Tenant will attorn to Mortgagee in the event of a foreclosure by Mortgagee or
the exercise of other rights under the Mortgage; and

     WHEREAS, Tenant wishes to obtain from Mortgagee certain assurances that
Tenant's possession of the Premises will not, subject to the terms and
conditions of this Agreement, be disturbed by reason of a foreclosure of the
lien of the Mortgage on the Real Property; and

     WHEREAS, Tenant and Mortgagee are both willing to provide such assurances
to each other upon and subject to the terms and conditions of this Agreement.

     NOW, THEREFORE, in consideration of the above, the mutual promises
hereinafter set forth, and other good and valuable consideration, the receipt
and sufficiency of which are hereby acknowledged, the parties hereto mutually
agree as follows:

<PAGE>

     1. AFFIRMATION. Tenant hereby agrees that the Lease now is and shall be
subject and subordinate in all respects to the Mortgage and to all renewals,
modifications and extensions thereof until such time that the Mortgage is
released, satisfied or otherwise discharged, subject to the terms and conditions
of this Agreement. Landlord and Tenant hereby affirm that the Lease is in full
force and effect and that the Lease has not been modified or amended. Mortgagee
hereby confirms that it is the holder of the Note and the beneficiary of the
Mortgage and has full power and authority to enter into this Agreement.

     2. ATTORNMENT AND NON-DISTURBANCE.

     (a) So long as Tenant is not in default under the Lease (beyond Tenant's
receipt of notice from Landlord and any grace period granted Tenant under the
Lease to cure such default) as would entitle the Landlord to terminate the Lease
or would cause without any further action of the Landlord, the termination of
the Lease or would entitle the Landlord to dispossess Tenant thereunder then
Mortgagee agrees with Tenant that in the event the interest of Landlord shall be
acquired by Mortgagee or in the event Mortgagee comes into possession of or
acquires title to the Real Property by reason of foreclosure or foreclosure sale
or the enforcement of the Mortgage or the Note or other obligation secured
thereby or by a conveyance in lieu thereof, or as a result of any other means
then:

          (i) Subject to the provisions of this Agreement, Tenant's occupancy
     and possession of the Premises and Tenant's rights and privileges under the
     Lease or any extensions, modifications or renewals thereof or substitutions
     therefor (in accordance with the Lease and the Mortgage) shall not be
     disturbed, diminished or interfered with by Mortgagee during the term of
     the Lease (or any extensions or renewals thereof provided for in the
     Lease);

          (ii) Mortgagee will not join Tenant as a party defendant in any action
     or proceeding for the purpose of terminating Tenant's interest and estate
     under the Lease because of any default under the Mortgage; and

          (iii) The Lease shall continue in full force and effect and shall not
     be terminated except in accordance with the terms of the Lease.

          (b) Tenant shall be bound to Mortgagee under all of the terms,
     covenants and conditions of the Lease for the balance of the term thereof
     remaining (and any extensions or renewals thereof which may be effected in
     accordance with any option contained in the Lease) with the same force and
     effect as if Mortgagee were the landlord under the Lease, and Tenant does
     hereby agree to attorn to Mortgagee as its landlord, said attornment to be
     effective and self-operative without the execution of any other instruments
     on the part of either party hereto immediately upon Mortgagee's succeeding
     to the interest of Landlord under the Lease. Upon request of Lender, Tenant
     shall execute and deliver to Lender an agreement reaffirming such
     attornment.

          (c) If the Mortgage is foreclosed and any party ("Purchaser") other
     than Mortgagee purchases the Premises and succeeds to the interest of
     Landlord under the Lease, Tenant shall likewise be bound to Purchaser and
     Tenant hereby covenants and

<PAGE>

     agrees to attorn to Purchaser in accordance with all of the provisions of
     this Agreement; provided, however, that Purchaser shall have transmitted to
     Tenant a written document in recordable form, whereby Purchaser agrees to
     recognize Tenant as its lessee under the Lease and agrees to be directly
     bound to Tenant for the performance and observance of all the terms and
     conditions of the Lease required to be performed or observed by Landlord
     thereunder, subject to and in accordance with the terms of this Agreement.

          (d) Mortgagee agrees that if Mortgagee shall succeed to the interest
     of Landlord under the Lease as above provided, Mortgagee shall be bound to
     Tenant under all of the terms, covenants, and conditions of the Lease, and
     Tenant shall, from and after Mortgagee's succession to the interest of
     Landlord under the Lease, have the same remedies against Mortgagee that
     Tenant might have had under the Lease against Landlord if Mortgagee had not
     succeeded to the interest of Landlord; provided, however, that Mortgagee
     (and Purchaser, as the case may be) shall not be:

               (i) liable for any act or omission of any prior lessor (including
     Landlord) occurring prior to the date that Mortgagee or Purchaser acquired
     title to the Premises;

               (ii) subject to any offsets, counterclaims or defenses which
     Tenant might have against any prior lessor (including Landlord);

               (iii) bound by any previous payment of rent or additional rent
     for a period greater than 1 month unless such prepayment shall have been
     consented to in writing by Mortgagee;

               (iv) bound by any amendment or modification of the Lease made
     prior to the date Mortgagee or Purchaser succeeds to the interest of
     Landlord without Mortgagee's written consent;

               (v) liable to Tenant for any toss of business or any other
     indirect or consequential damages from whatever cause; provided, however,
     no inference shall be drawn from this clause (v) that Tenant would
     otherwise be entitled (or not entitled) to recover for loss of business or
     any other indirect or consequential damages; or

               (vi) liable for the return of any security deposit unless such
     deposit has been paid over to the Mortgagee.

     The foregoing shall not be construed to modify or limit any right Tenant
may have at law or in equity against Landlord or any other prior owner of the
Real Property.

<PAGE>

     3. NOTICES. All notices required or permitted to be given pursuant to this
Agreement shall be in writing and shall be sent postage prepaid, by certified
mail, return receipt requested or other nationally utilized overnight delivery
service. All notices shall be deemed delivered when received or refused.
Rejection or other refusal to accept or inability to deliver because of changed
address of which no notice has been given shall constitute receipt of the
notice, demand or request sent. Any such notice if given to Tenant shall be
addressed as follows:

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

     if given to Landlord shall be addressed as follows:

     c/o Alexandria Real Estate Equities, Inc.
     135 N. Los Robles Avenue
     Suite 250
     Pasadena, California 91101
     Attention: General Counsel

     if given to Mortgagee shall be addressed as follows:

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

     4. SUCCESSORS AND ASSIGNS. This Agreement shall be binding upon and inure
to the benefit of the parties hereto and their respective successors and
assigns. The words "foreclosure" and "foreclosure sale" as used herein shall be
deemed to also include the acquisition of Landlord's estate in the Real Property
by voluntary deed, assignment or other conveyance or transfer in lieu of
foreclosure.

     5. MODIFICATIONS TO LEASE. Tenant shall not modify or amend the Lease or
terminate the same without Mortgagee's prior written consent. If Mortgagee fails
to provide Tenant with a written approval of the proposed modification,
amendment or termination within 10 business days after notice to Mortgagee of
such proposal, then Mortgagee shall be deemed to have rejected such proposal.

     6. ADDITIONAL AGREEMENTS. Tenant agrees that:

     (a) it shall give Mortgagee copies of all notices of default and requests
for approval or consent by Landlord that Tenant gives to Landlord pursuant to
the Lease in the same manner as they are given to Landlord and no such notice or
other communication shall be deemed to be effective until a copy is given to
Mortgagee;

<PAGE>

     (b) whenever any consent or approval by Landlord is required to be obtained
by Tenant or is requested by Tenant such consent or approval shall not be
effective until it is also confirmed by or obtained from Mortgagee, provided
that Mortgagee shall respond within 30 days after Mortgagee's receipt of
Tenant's request and failure of Mortgagee to respond in such time period shall
be deemed to be a denial of such consent or approval;

     (c) in all provisions of the Lease where Landlord is indemnified, the
reference to Landlord as an indemnitee shall be deemed to include Mortgagee and
any Purchaser and such agreement of indemnification shall survive the repayment
of the loan secured by the Mortgage and, to the extent provided in the Lease,
the expiration or termination of the Lease;

     (d) Tenant shall name Mortgagee and any Purchaser as additional insureds
and loss payees, as applicable and appropriate, on all insurance policies
required by the Lease;

     (e) this Agreement satisfies any condition or requirement in the Lease
relating to the granting of a non-disturbance agreement by Mortgagee, and if
there are inconsistencies between the terms and provisions of this Agreement and
the terms and provisions of the Lease dealing with non-disturbance by Mortgagee,
the terms and provisions hereof shall be controlling; and

     (f) Mortgagee shall have no liability under the Lease until Mortgagee
succeeds to the rights of the Landlord under the Lease, and then only during
such period as Mortgagee is the landlord. At all times during which Mortgagee is
liable under the Lease, Mortgagee's liability shall be limited to Mortgagee's
interest in the Real Property.

     7. MORTGAGEE CURE RIGHTS. If Landlord shall have failed to cure any default
within the time period provided for in the Lease (including any applicable
notice and grace periods) and Tenant exercises any right to terminate the Lease,
Mortgagee, shall have an additional 30 days within which to cure to cure such
default, or if such default cannot by the exercise of reasonable efforts by
Mortgagee be cured within such period, then such additional time as may be
reasonable necessary to effect such a cure (including, if necessary, sufficient
time to complete foreclosure proceedings) provided that Mortgagee shall commence
and thereafter diligently pursue remedies to cure such default. The Lease shall
not be terminated (i) while such remedies are being diligently pursued or (ii)
based upon a default which is personal to Landlord and therefore not susceptible
to cure by Mortgagee or which requires possession of the Premises to cure.
Mortgagee shall in no event be obligated to cure any such default by Landlord
unless it forecloses. Nothing in this Section 7 shall affect any of Tenant's
termination rights under the Lease due to casualty or condemnation.

     8. DIRECTION TO PAY. Landlord hereby directs Tenant and Tenant agrees to
make all payments of amounts owed by Tenant under the Lease directly to
Mortgagee from and after receipt by Tenant of written notice from Mortgagee
directing Tenant to make such payments to Mortgagee. Tenant shall have the right
to rely on any such notice from Mortgagee and Mortgagee hereby indemnifies and
agrees to defend Tenant against any action by Landlord arising from Tenant's
reliance on such notice. (As between Landlord and Mortgagee, the foregoing
provision shall not be construed to modify any rights of Landlord under or any
provisions of the Mortgage or any other instrument securing the Note).

<PAGE>

     9. CONDITIONAL ASSIGNMENT. With reference to any assignment by Landlord of
Landlord's interest in the Lease, or the rents payable thereunder, conditional
in nature or otherwise, which assignment is made to Mortgagee, Tenant agrees
that the execution thereof by Landlord, and the acceptance thereof by Mortgagee
shall never be treated as an assumption by Mortgagee of any of the obligations
of Landlord under the Lease unless and until Mortgagee shall have succeeded to
the interest of Landlord. The foregoing sentence shall not affect any of
Tenant's rights against Landlord under the Lease.

                           [SIGNATURES ON NEXT PAGE]
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
properly executed by their duly authorized representatives as of the date first
above written.

TENANT:
                                           ---------------------------------
                                           a--------------------------------

                                           By:
                                              ------------------------------
                                           Its:
                                               -----------------------------

LANDLORD:                                  [INSERT APPROPRIATE SIGNATURE BLOCK]

MORTGAGEE:
                                           ---------------------------------
                                           a--------------------------------

                                           By:
                                              ------------------------------
                                             Name:
                                                  --------------------------
                                             Its:
                                                 ---------------------------

<PAGE>

                      EXHIBIT A TO SUBORDINATION AGREEMENT

                                Legal Description

<PAGE>

                                   EXHIBIT A


Floor plan of one Innovation Drive, 1st Floor Premises of
t.Breeders, 12,254 SF



<PAGE>

                                   WORK LETTER

                                   SCHEDULE B

Floor plan of one Innovation Dr., 1st Floor, Premises of t.Breeders, Inc.
<PAGE>

                            FIRST AMENDMENT TO LEASE

     This First Amendment to Lease ("First Amendment") is made as of May 31,
2001, by and between ARE-ONE INNOVATION DRIVE, LLC, a Delaware limited liability
company ("Landlord"), and VIACELL, INC., a Delaware corporation ("TENANT")

                                    RECITALS

     A. Landlord is the landlord and Tenant is the tenant under a Lease dated as
of February 24, 2000 (the "Lease"), between Landlord and Tenant's predecessor by
name change t.Breeders, Inc., under which Tenant leases approximately 12,254
rentable square feet of space in the building commonly known as One Innovation
Drive, Worcester, Massachusetts. Capitalized terms used herein without
definition shall have the meanings defined for such terms in the Lease.

     B. Landlord and Tenant desire to amend the Lease to expand the Premises
[illegible] demised thereunder to consist of current [illegible] space and
adding approximately 4,947 rentable square feet to the Premises demised under
the Lease in three locations as follows:

          (a) approximately 1,578 rentable square feet located on the 4th floor
of the Building, as depicted on EXHIBIT A1 attached hereto and incorporated
herein by this reference ("EXPANSION SPACE ONE");

          (b) approximately 2,263 rentable square feet located on the 4th floor
of the Building, as depicted on EXHIBIT A2 attached hereto and incorporated
herein by this reference ("EXPANSION SPACE TWO"); and

          (c) approximately 1,106 rentable square feet located on the 1st floor
of the Building, as depicted on EXHIBIT A3 attached hereto and incorporated
herein by this reference ("Expansion Space Three");

(collectively, the "EXPANSION SPACE").

     C. Landlord and Tenant desire to amend the Lease to, among other things,
add the Expansion Space to the Premises demised under the Lease and to provide
for the improvement of such space.

                                    AGREEMENT

     Now, therefore, the parties hereto agree that the Lease is hereby amended
as follows:

1. THE PREMISES. Effective as June 1, 2001, the Premises demised under the Lease
shall include Expansion Space One (consisting for all purposes of the Lease of
1,578 rentable square feet). The monthly Base Rent payable for the month of June
2001 shall be increased by $3,090.25 to $21,726.55 and Tenant's Share of
Operating Expenses during such month shall be 12.01%. Effective as July 1, 2001,
the Premises demised under the Lease shall include Expansion Space Two
(consisting for all purposes of the Lease of 2,263 rentable square feet) and
Expansion Space Three (consisting for all purposes of the Lease of 1,106
rentable square feet). From and after July 1, 2001 the monthly Base Rent payable
under the Lease shall be increased by $6,597.63 per

<PAGE>

month to $28,324.18 per month and Tenant's Share of Operating Expenses shall be
14.93%. Such Base Rent shall thereafter be subject to adjustment when and as
described in Section 4(b) of the Lease.

2. TERM: ACCEPTANCE OF PREMISES. The term of the lease of the Expansion Space
(the "TERM") shall commence as described in Section 1 above, shall be year to
year and shall be automatically renewed unless either Landlord or Tenant gives
notice on or before December 31 of any year of its election not to renew, in
which event the lease of the Expansion Space shall terminated on April 30 of the
following year (approximately 4 months later); provided, however that in all
events the lease of the Expansion Space shall terminate when the Term of the
Lease terminated. Tenant shall accept the Expansion Space in its condition as of
the date of delivery of such Expansion Space to Tenant, subject to all
applicable Legal Requirements. Upon such delivery, Landlord shall have no
obligation for any defects in the Expansion Space. Tenant's taking possession of
each increment of the Expansion Space shall be conclusive evidence that Tenant
accepts such portion of the Expansion Space and that such portion of the
Expansion Space was in good condition at the time possession was taken.

3. SECURITY DEPOSIT. Upon delivery to Landlord of a copy of this First Amendment
executed by Tenant, Tenant shall deliver to Landlord a cash deposit (3 months
rent) acceptable to Landlord (the "SECURITY DEPOSIT") in the amount of
$29,063.25 as security for Tenant's performance under the Lease.

4. ALTERATIONS. Any alteration of all or a portion of the Expansion Space shall
be subject to all of the provisions of Section 12 of the Lease.

5. MISCELLANEOUS.

     (a) This First Amendment is the entire agreement between the parties with
respect to the subject matter hereof and supersedes all prior and
contemporaneous oral and written agreements and discussions with respect to the
matters addresses herein. This Amendment may be amended only by an agreement in
writing, signed by the parties hereto.

     (b) This First Amendment is binding upon and shall insure to the benefit of
the parties hereto, their respective agents, employees, representatives,
officers, directors, divisions, subsidiaries, affiliates, assigns, heirs,
successors in interest and shareholders.

     (c) The First Amendment may be executed in any number of counterparts, each
of which shall be deemed an original, but all of which when taken together shall
constitute one and the same instrument. The signature page of any counterpart
may be detached therefrom without impairing the legal effect of the signature(s)
thereon provided such signature page is attached to any other counterpart
identical thereto except having additional signature pages executed by other
parties to this Amendment attached thereto.

     (d) Landlord and Tenant each represent and warrant that it has not dealt
with any broker, agent or other person (collectively "BROKER") in connection
with this transaction, and that no Broker brought about this transaction.
Landlord and Tenant each hereby agree to Indemnify and hold the other harmless
from and against any claims by any Broker

                                      - 2 -
<PAGE>

claiming a commission or other form of compensation by virtue of having dealt
with Tenant or Landlord, as applicable, with regard to this leasing transaction.

     (e) Except as amended and/or modified by this Amendment, the Lease is
hereby ratified and confirmed and all other terms of the Lease shall remain in
full force and effect, unaltered and unchanged by this Amendment. In the event
of any conflict between the provisions of this Amendment and the provisions of
the Lease, the provisions of this Amendment shall prevail. Whether or not
specifically amended by this Amendment, all of the terms and provisions of the
Lease are hereby amended to the extent necessary to give effect to the purpose
and intent of this Amendment

                           [signatures on next page]

<PAGE>
     IN WITNESS WHEREOF, this First Amendment to Lease has been duly executed
and delivered by Landlord and Tenant as of the date first above written.

                                        TENANT:

                                        VIACELL, INC.
                                        a Delaware corporation

                                        By: Signature on file
                                           ------------------------------------
                                        Its: CEO
                                            -----------------------------------

                                        LANDLORD:
                                        ARE-One Innovation Drive, LLC,
                                        a Delaware limited liability company

                                        By: ALEXANDRIA REAL ESTATE EQUITIES,
                                            L.P.,
                                            a Delaware limited partnership,
                                            managing member

                                        By: ARE-QRS CORP.,
                                            a Maryland corporation,
                                            general partner

                                            By: Michael C. Keley
                                               --------------------------------
                                            Its: Senior Vice President
                                                -------------------------------
                                                 Real Estate Legal Affairs


                                      - 3 -
<PAGE>

                                   EXHIBIT A-1

                      Depiction of the Expansion Space One





                                      - 4 -
<PAGE>

                                   EXHIBIT A-2

                      Depiction of the Expansion Space Two




                                      - 5 -
<PAGE>

                                   Exhibit A-3
                     Depiction of the Expansion Space Three




                                      - 6 -