Document:

<PAGE>

                                                                    EXHIBIT 10.7

                             EMPLOYMENT AGREEMENT
                             --------------------

     This Employment Agreement is entered into as of January 21, 1998 (the
"Effective Date"), by and between XENOGEN CORPORATION, a California corporation
(the "Company"), and DAVID CARTER (the "Employee").

     1.   At-Will Employment.  The Employee's employment with the Company is for
          ------------------
an unspecified duration and constitutes "at-will" employment.  The Employee
acknowledges that the employment relationship may be terminated at any time,
with or without good cause or for any or no cause, at the option either of the
Company or the Employee, with or without notice.  Employee will devote his full
business time and attention to his employment with the Company with the
exception of time spent on other business endeavors; provided, however, Employee
                                                     --------  -------
will not serve as an executive officer or have operational responsibility for
any other business.

     2.   Salary.  For all services to be rendered by the Employee to the
          ------
Company, the Company agrees to pay the Employee an annual salary of $175,000 in
accordance with the Company's standard payroll policies.

     3.   Benefits.  During the Employee's employment with the Company, the
          --------
Employee shall be entitled to participate in employee benefit plans or programs
of the Company ("Benefit Plans"), if any, to the extent that the Employee's
position, tenure, salary, age, health and other qualifications make the Employee
eligible to participate, subject to the rules and regulations applicable
thereto.

     4.   Life Insurance.  The Company will pay a $25,000 annual premium for
          --------------
split dollar life insurance on behalf of the Employee.

     5.   Termination of Employment.
          -------------------------

          (a)  Voluntary Resignation/Termination For Cause.  If the Employee
               -------------------------------------------
voluntarily resigns or is terminated by the Company for Cause (as defined
below), then:

               (i)    no salary will be paid for the periods following the date
of termination;

               (ii)   no benefits will be paid or provided for the periods
following the date of termination; and

               (iii)  the number of shares exercisable under the Employee's
outstanding options, if any, and the Company's right to repurchase the
Employee's outstanding Common Stock shall be measured as of the date of
termination.

          (b)  Termination Without Cause.  If the Employee is terminated by the
               -------------------------
Company without Cause (as defined below) within one year from the date of the
Agreement, then:
<PAGE>

               (i)    the Employee's annual salary will continue to be paid in
accordance with the Company's standard payroll policies for six months following
the date of termination;

               (ii)   the Employee will continue to receive benefits pursuant to
the Company's Benefit Plans, provided that such Benefit Plans permit
continuation post-termination, at the Company's expense for six months following
the date of termination; and

               (iii)  the number of shares exercisable under the Employee's
outstanding options, if any, and the Company's right to repurchase the
Employee's outstanding Common Stock shall be measured as if the termination
occurred six months from the actual date of termination; provided, however, that
                                                         --------  -------
the Company's right to repurchase 250,000 shares of Common Stock issued to the
Employee in conjunction with the Series C Preferred Stock Purchase Agreement of
even date herewith and subject to that certain Restricted Stock Purchase
Agreement of even date herewith shall be determined as of the actual date of
termination.

     The post-employment payments and benefits under Sections 5(b)(i) and (ii)
shall be terminated prior to one year from the date of termination upon the
acceptance by the Employee of new employment.

          (c)  Termination Without Cause.  If the Employee is terminated by the
               -------------------------
Company without Cause (as defined below) following one year from the date of
this Agreement and prior to two years from the date of this Agreement, then:

               (i)    the Employee's annual salary will continue to be paid in
accordance with the Company's standard payroll policies for nine months
following the date of termination;

               (ii)   the Employee will continue to receive benefits pursuant to
the Company's Benefit Plans, provided that such Benefit Plans permit
continuation post-termination, at the Company's expense for nine months
following the date of termination; and

               (iii)  the number of shares exercisable under the Employee's
outstanding options, if any, and the Company's right to repurchase the
Employee's outstanding Common Stock shall be measured as if the termination
occurred nine months from the actual date of termination; provided, however,
                                                          --------  -------
that the Company's right to repurchase 250,000 shares of Common Stock issued to
the Employee in conjunction with the Series C Preferred Stock Purchase Agreement
of even date herewith and subject to that certain Restricted Stock Purchase
Agreement of even date herewith shall be determined as of the actual date of
termination.

     The post-employment payments and benefits under Sections 5(c)(i) and (ii)
shall be terminated prior to one year from the date of termination upon the
acceptance by the Employee of new employment.

          (d)  Termination Without Cause.  If the Employee is terminated by the
               -------------------------
Company without Cause (as defined below) following two years from the date of
this Agreement, then:

               (i)    the Employee's annual salary will continue to be paid in
accordance with the Company's standard payroll policies for one year following
the date of termination;
<PAGE>

               (ii)   the Employee will continue to receive benefits pursuant to
the Company's Benefit Plans, provided that such Benefit Plans permit
continuation post-termination, at the Company's expense for one year following
the date of termination; and

               (iii)  the number of shares exercisable under the Employee's
outstanding options, if any, and the Company's right to repurchase the
Employee's outstanding Common Stock shall be measured as if the termination
occurred one year from the actual date of termination; provided, however, that
                                                       --------  -------
the Company's right to repurchase 250,000 shares of Common Stock issued to the
Employee in conjunction with the Series C Preferred Stock Purchase Agreement of
even date herewith and subject to that certain Restricted Stock Purchase
Agreement of even date herewith shall be determined as of the actual date of
termination.

     The post-employment payments and benefits under Sections 5(d)(i) and (ii)
shall be terminated prior to one year from the date of termination upon the
acceptance by the Employee of new employment.

          (e)  As used in this Agreement, Cause shall mean:

               (i)    the Employee's failure to substantially perform the duties
associated with the Employee's position;

               (ii)   the Employee's personally engaging in conduct that the
Employee reasonably should know or that the Employee intends to be seriously
injurious to the Company, its affiliates or employees;

               (iii)  a material and willful violation of a federal or state law
or regulation applicable to the business of the Company;

               (iv)   the Employee's being convicted of a felony under the laws
States or any State, or the misappropriation of material property belonging
to, the Company or its affiliates; or

               (v)    the Employee knowingly and intentionally breaching in any
material respect the terms of the Employee's Proprietary Information Agreement.

     6.   Arbitration.  Any dispute or controversy arising under or in
          -----------
connection with this Agreement shall be settled exclusively by arbitration in
Palo Alto, California, in accordance with the rules of the American Arbitration
Association then in effect by an arbitrator selected by both parties within 20
days after either party has notified the other in writing that it desires a
dispute between them to be settled by arbitration. In the event the parties
cannot agree on such arbitrator within such 20-day period, each party shall
select an arbitrator and inform the other party in writing of such arbitrator's
name and address within 5 days after the end of such 20-day period and the two
arbitrators so selected shall select a third arbitrator within 15 days
thereafter; provided, however, that in the event of a failure by either party to
            --------  -------
select an arbitrator and notify the other party of such selection within the
time period provided above, the arbitrator selected by the other party shall be
the sole arbitrator of the dispute. Each party shall pay its own expenses
associated with such arbitration, including the expense of any arbitrator
<PAGE>

selected by such party and the Company will pay the expenses of the jointly
selected arbitrator. The decision of the arbitrator or a majority of the panel
of arbitrators shall be binding upon the parties and judgment in accordance with
that decision may be entered in any court having jurisdiction thereover.
Punitive damages shall not be awarded.

     7.   Notices.  For purposes of this Agreement, notices and other
          -------
communications provided for in this Agreement shall be in writing and shall be
delivered personally or sent by United States certified mail, return receipt
requested, postage prepaid, to the address set forth on the signature pages to
this Agreement.

     8.   Applicable Law.  This Agreement shall be governed by and construed in
          --------------
accordance with the internal substantive laws of the State of California without
reference to choice or conflicts of law.

     9.   Counterparts.  This Agreement may be executed in one or more
          ------------
counterparts, none of which need contain the signature of more than one party
hereto, and each of which shall be deemed to be an original, and all of which
together shall constitute a single agreement.
<PAGE>

     IN WITNESS WHEREOF, each of the parties has executed this Agreement, in the
case of the Company by its duly authorized officer, as of the day and year first
above written.

"COMPANY"                                    "EMPLOYEE"

By: /s/ Pamela Reilly Contag                 /s/ David Carter
   --------------------------------          ----------------------------------
                                             David Carter
Title:_____________________________

Address:                                     Address:

___________________________________          __________________________________

___________________________________          __________________________________
<PAGE>

                                                        Xenogen Employee Matters
                                                                  "David Carter"

                                 June 10 1997

Mr. David Carter
240 Monte Vista Ridge Road
Orinda, CA 94563

Dear David:

     The purpose of this letter is to set forth the terms of the cash and equity
compensation to be provided to you in connection with your consulting services
to Xenogen Corporation ("Xenogen"). Our understanding is as follows:

     1.   Consulting Fee.
          --------------
          You to be paid an annual consulting fee of $100,000 per year. You will
          be available to Xenogen to work two days a week under this
          arrangement. The fee to be paid you will accrue until Xenogen has
          obtained equity financing of at least $2,000,000, at which time it may
          be repaid or converted into equity at your sole option. In connection
          with the consulting agreement, you will sign Xenogen's standard
          proprietary information agreements and confidentiality agreements.
          Your consulting agreement may be terminated by either party at any
          time.

     2.   Founder Stock Purchase Agreement.
          --------------------------------
          You will be entitled to purchase up to 400,000 shares of Xenogen
          Common Stock at a purchase price of $0.05 per share. The stock
          purchased by you will be subject to a right of repurchase held by
          Xenogen which will lapse as to 1/4 of the shares 1 year following your
          engagement as a consultant and an additional 1/48 on the first day of
          each month thereafter, based upon your continued service to Xenogen as
          a consultant or employee. The 400,000 shares is 11.93% of the
          currently outstanding stock (all common stock and preferred stock
          outstanding plus options issued under Xenogen's stock plan). If you
          wish, these 400,000 shares may be issued to him in the form of an
          option exercisable at $0.05 per share vesting over a period of four
          years.

<PAGE>

David Carter
June 10, 1997
Page 2

     3.   Stock Purchase Warrant.
          ----------------------
          Xenogen will issue to you a warrant to purchase the securities sold in
          Xenogen's next equity financing. The number of shares for which the
          warrant shall be exercisable shall be equal to 15% of the shares sold
          in such financing. The exercise price of the warrant shall be 125% of
          the price paid by the purchasers in Xenogen's next equity financing.
          The warrant will have a term of five years and will contain a net
          exercise provision.

     If you have any questions regarding the foregoing, please feel free to
contact me at any time.

                                             Very truly yours,

                                             XENOGEN CORPORATION

                                             /s/ Pamela Reilly Contag

                                             Pamela Contag
                                             President

Agreed and accepted this
10th day of June, 1997

/s/ David Carter
------------------------
David Carter<PAGE>

                                                                Exhibit 10.8(ii)

                                MARINA VILLAGE
                            NET OFFICE -TECH LEASE
                            BASIC LEASE INFORMATION
                            -----------------------

<TABLE>
<S>                        <C>                                                         <C>
DATE:                      June 6, 2000

LANDLORD:                  ALAMEDA REAL ESTATE INVESTMENTS,
                           a California limited partnership

TENANT:                    XENOGEN CORPORATION,
                           a California corporation

                                                                                       Lease Reference
                                                                                       ---------------
PREMISES AND BUILDING:     Approximately 21,297 rentable square feet ("rsf")           Paragraph l
                           located at 2061 Challenger Drive, Suite 100,
                           101 and 103, Alameda, California

TERM COMMENCEMENT:         June 15, 2000                                               Paragraph 2

TERM EXPIRATION:           February 28, 2006                                           Paragraph 2

BASE RENT:                 6/15/00 - 10/31/00  $5,040/month                            Paragraph 3(a)
                           11/1/00 - 2/28/01   $31,936/month
                            3/1/01 - 5/31/01   $42,594/month
                            6/1/01 - 5/31/02   $44,298/month
                            6/1/02 - 5/31/03   $46,002/month
                            6/1/03 - 5/31/04   $47,918/month
                            6/1/04 - 5/31/05   $49,835/month
                            6/1/05 - 2/28/06   $51,752/month

TENANT'S PERCENTAGE        2,880 rsf / 35,348 rsf = 8.15%,                             Paragraph 4(a)
SHARE:                     effective at Lease Commencement

                           15,968 rsf / 35,348 rsf = 45.17%,
                           effective November 1, 2000
                           21,297 rsf / 35,348 rsf = 60.25%,
                           effective March 1, 2001

USE:                       Office, biotechnology/pharmaceutical research and           Paragraph 6
                           development including small live animal storage, and
                           related manufacturing and warehousing

SECURITY DEPOSIT:          $20,000 (See Addendum)                                      Paragraph 15

TENANT'S ADDRESS FOR       860 Atlantic Avenue                                         Paragraph 19
NOTICES:                   Alameda, CA 94501
</TABLE>
<PAGE>

<TABLE>
<S>                                                    <C>                             <C>
LANDLORD'S ADDRESS FOR                                                                 Paragraph 19
NOTICES:

Alameda Real Estate Investments                        With a Copy To:
                                                       ---------------
c/o Vintage Properties                                 Marina Village
Attn:  Joseph R. Seiger                                1150 Marina Village Pkwy.
                                                       Suite 100
314 Lytton Avenue, Suite 200                           Alameda, CA 94501
Palo Alto, CA 94301                                    Attn:  Property Manager

EXHIBIT(S) AND ADDENDUM(S):                                                            Paragraph 21
</TABLE>

Exhibit A:  Diagram of Premises
Exhibit B:  Tenant Improvements
Exhibit C:  Subordination, Non-Disturbance and Attornment Agreement
Addendum

The provisions of the Lease identified above in the margin are those provisions
where references to particular Basic Lease Information appear.  Each such
reference shall incorporate the applicable Basic Lease Information.  In the
event of any conflict between any Basic Lease Information and the Lease, the
latter shall control.

<TABLE>
<CAPTION>
TENANT:                                                   LANDLORD:
<S>                                                     <C>
XENOGEN CORPORATION,                                      ALAMEDA REAL ESTATE INVESTMENTS,
a California corporation,                                 a California limited partnership

By:_______________________                                By:  Vintage Alameda Investments, LP
Name: ____________________                                     a California limited partnership
Title: ___________________                                     operating general partner

By:_______________________                                     By:  Vintage Properties - Alameda Commercial,
Name: ____________________                                          a California corporation,
Title: ___________________                                          managing general partner

                                                                    By:_______________________________
                                                                    Title :  President

</TABLE>

                                       2
<PAGE>

                                MARINA VILLAGE

                             NET OFFICE-TECH LEASE

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

     THIS LEASE, ("Lease") dated as of June 6, 2000, for purposes of reference
                   -----
only, is made and entered into by and between ALAMEDA REAL ESTATE INVESTMENTS, a
California limited partnership ("Landlord"), and XENOGEN CORPORATION, a
                                 --------
California corporation ("Tenant").
                         ------

                                   WITNESSETH

     1.   Premises. Landlord hereby leases to Tenant, and Tenant hereby leases
          --------
from Landlord for the term of this Lease and at the rental and upon the
conditions set forth below, the premises described in the Basic Lease
Information and identified on the diagram attached hereto as Exhibit A (the
                                                             ---------
"Premises") Landlord and Tenant agree that the amount of rentable square feet as
 --------
set forth in the Basic Lease Information or, if such amount is an approximation,
the final rentable square feet as determined upon completion of working
drawings, shall be binding and conclusive for all purposes of this Lease.
Subject to any obligations of Landlord as set forth in an exhibit to this Lease
relating to initial improvement of the premises, Tenant shall accept the
premises in its "as-is" condition at the commencement of the term. The premises
are located within the building (the "Building") commonly known as described in
                                      --------
the Basic Lease Information.

     2.   Term.

               (a)  The term of this Lease shall commence and, unless sooner
terminated as hereinafter provided, shall end on the dates respectively
specified in the Basic Lease Information. If Landlord, for any reason
whatsoever, cannot deliver possession of the premises to Tenant at the
commencement of the term, this Lease shall not be void or voidable, nor shall
Landlord be liable to Tenant for any loss or damage resulting therefrom, but in
that event, subject to any contrary provisions in any agreement with Landlord
related to the initial improvement of the premises, rental shall be waived for
the period between commencement of the term and the time when Landlord can
deliver possession. If, for any reason beyond Landlord's reasonable control,
Landlord is unable to obtain necessary governmental approvals to complete and
deliver possession of the premises by August 1, 2000 to Tenant, then Landlord or
Tenant may, upon notice to the other third party, terminate this Lease and both
parties shall be relieved of any and all obligations hereunder.

               (b)  Prior to the commencement of the term, Landlord shall
complete the Tenant Improvements to be constructed or installed in the premises
pursuant to Exhibit B attached hereto. The Tenant Improvements shall be deemed
            ---------
completed and possession of the premises delivered when Landlord has
substantially completed the Tenant Improvements, subject only to the completion
of minor items which do not materially impair the usability of the Tenant
Improvements by Tenant, and Tenant shall accept the premises upon notice from
Landlord that the Tenant Improvements have been so completed.

                                       3
<PAGE>

     3.   Rent.
          ----

               (a)  Tenant shall pay to Landlord as rental the amount specified
in the Basic Lease Information as the Base Rent, payable in advance on the
commencement of the term and on or before the first day of each and every
successive calendar month during the term. If the term commences on other than
the first day of a calendar month, the first payment of rent shall be
appropriately prorated on the basis of a 30-day month. The anniversary date for
rental increases as set forth in the Basic Lease Information shall be the first
calendar day of the month in which the Lease term commenced. If the last day of
the term falls on a date other than the last day of the month, then the term
shall be extended so that the last day of the term shall be the last calendar
day of the month in which the term would otherwise end.

               (b)  Tenant shall pay, as additional rent, all amounts of money
required to be paid to Landlord by Tenant under this Lease in addition to
monthly rent, whether or not the same be designated "additional rent". If such
                                                     ---------------
amounts are not paid at the time provided in this Lease, they shall nevertheless
be a collectable as additional rent with the next installment of monthly rent
thereafter falling due, but nothing herein contained shall be deemed to suspend
or delay the payment of any amount of money at the time the same becomes due and
payable hereunder, or limit any other remedy of Landlord.

               (c)  Tenant hereby acknowledges that late payment by the Tenant
to Landlord of rent and other amounts due hereunder will cause Landlord to incur
costs not contemplated by this Lease, the exact amount of which will be
extremely difficult to ascertain. Such costs include, but are not limited to,
processing and accounting charges, and late charges which may be imposed on
Landlord by the terms of any trust deed covering the premises. Accordingly, if
any installments of rent or any other sums due from Tenant shall not be received
by Landlord when due, then Tenant shall pay to Landlord a late charge equal to
six percent (6%) of such overdue amount. The parties hereby agree that such late
charges represent a fair and reasonable estimate of the costs Landlord will
incur by reason of late payment by Tenant. Acceptance of such late charge by
Landlord shall in no event constitute a waiver of Tenant's default with respect
to such overdue amount, nor prevent Landlord from exercising any of the other
rights and remedies granted hereunder

               (d)  Any amount due to Landlord, if not paid when due, shall bear
interest from the date due until the date paid at the rate of ten percent (10%)
per annum, provided that interest shall not be payable on late charges incurred
by Tenant nor on any amounts upon which late charges are paid by Tenant to the
extent such interest would cause the total interest to be in excess of that
legally permitted. Payment of interest shall not excuse or cure any default
hereunder by Tenant.

               (e)  All payments due from Tenant to Landlord hereunder shall be
made to Landlord without deduction or offset in lawful money of the United
States of America at Landlord's address for notices hereunder, or to such other
person or at such other place as Landlord may from time to time designate in
writing to Tenant.

                                       4
<PAGE>

     4.   Taxes and Operating Expenses.
          ----------------------------

               (a)  Tenant shall pay its percentage share, as specified in the
Basic Lease Information, of all Property Taxes assessed with respect to the
Building during the Lease term and its percentage share of all Operating
Expenses paid or incurred by Landlord during the Lease term. For the purposes
hereof, "Property Taxes" shall mean all real property taxes and assessments or
         -------- -----
governmentally imposed fees or charges (and any tax levied wholly or partly in
lieu thereof) levied, assessed, confirmed, imposed or which have become a lien
against the Building (which for the purposes of defining "Property Taxes" shall
include the land underlying the Building), and "Operating Expenses" shall mean:
                                                ------------------
(1) all costs of management, operation, maintenance, and repair of the Building,
(2) the cost of all insurance maintained by Landlord with respect to the
Building and (3) the share allocable to the Building of dues and assessments
payable under any reciprocal easement or common area maintenance agreements or
declaration or by any owners' associations affecting the Building. Landlord
shall credit against Taxes otherwise payable by Tenant during any tax fiscal
year any tax increment reimbursements from the West End Community Improvement
District received by Landlord for the same period from secured roll real
property taxes attributable to the Building.

               (b)  In the event the Building is not separately assessed for tax
purposes, then the Property Taxes to be paid by Tenant shall be Tenant's
percentage share of the product obtained by multiplying the total of the real
property taxes and assessments levied against the tax parcel of which the
Building is a part, less the credit for tax increment reimbursements described
above, by a fraction, the numerator of which is the rentable area of the
Building and the denominator of which is total rentable area of all improvements
located within the tax parcel of which the Building is a part.

               (c)  Tenant shall pay to Landlord each month at the same time and
in the same manner as monthly Base Rent 1/12th of Landlord's estimate of
Property Taxes and Operating Expenses for the then current calendar year. Within
ninety (90) days after the close of each calendar year, or as soon after such
90-day period as practicable, Landlord shall deliver to Tenant a statement of
actual Property Taxes and Operating Expenses for such calendar year. If on the
basis of such statement Tenant owes an amount that is less than the estimated
payments for such calendar year previously made by Tenant, Landlord shall refund
such excess to Tenant. If on the basis of such statement Tenant owes an amount
that is more than the estimated payments for such calendar year previously made
by Tenant, Tenant shall pay the deficiency to Landlord within thirty (30) days
after delivery of the statement. The obligations of Landlord and Tenant under
this subparagraph with respect to the reconciliation between estimated payments
and actual Property Taxes and Operating Expenses for the last year of the term
shall survive the termination of the Lease.

     5.   Other Taxes. Tenant shall pay or reimburse Landlord for any taxes
          -----------
upon, measured by or reasonably attributable to the cost or value of Tenant's
equipment, furniture, fixtures, and other personal property located in the
premises or leasehold improvements made in or to the premises at Tenant's
expense; for any taxes, if any, measured by or reasonably attributable to Tenant
Improvements paid for by Landlord or Tenant in excess of $30.00 per square foot;
for any taxes, assessments, fees, or charges imposed by any public authority or
private community maintenance association upon or by reason of the development,
possession, use or occupancy of

                                       5
<PAGE>

the premises or the parking facilities used by Tenant in connection with the
premises; and for any gross receipts tax imposed with respect to the rental
payable hereunder.

     6.   Use.
          ---

               (a)  The premises shall be used and occupied by Tenant solely for
the use set forth in the Basic Lease Information. Tenant shall, at Tenant's
expense, comply promptly with all applicable statutes, ordinances, rules,
regulations, orders, and requirements in effect during the term regulating
Tenant's activities or the use by Tenant of the premises. Tenant shall not use
or permit the use of the premises in any manner that will tend to create waste
or a nuisance, or which shall tend unreasonably to disturb other tenants of the
Building or adjacent buildings, nor shall Tenant place or maintain any signs on
or visible from the exterior of the premises without Landlord's written consent,
or use any corridors, sidewalks, or other areas outside of the premises for
storage or any purpose other than access to the premises. Except as provided in
paragraph 6(b) below, Tenant shall not use, keep, or permit to be used or kept
on the premises any foul or noxious gas or substance, nor shall Tenant do or
permit to be done anything in and about the premises, either in connection with
activities hereunder expressly permitted or otherwise, which would cause a
cancellation of any policy of insurance (including fire insurance) maintained by
Landlord in connection with the premises or the Building or which would violate
the terms of any covenants, conditions, or restrictions affecting the Building
or the land on which it is located.

          (b)  Tenant shall strictly comply with all statutes, laws, ordinances,
rules, regulations, and precautions now or hereafter mandated or advised by any
federal, state, local or other governmental agency with respect to the use,
generation, storage, or disposal of hazardous, toxic, or radioactive materials
(collectively, "Hazardous Materials").  As herein used, Hazardous Materials
                -------------------
shall include, but not be limited to, those materials identified in Sections
66680 through 66685 of Title 22 of the California Code of Regulations, Division
4, Chapter 30, as amended from time to time, and those substances defined as
"hazardous substances," "hazardous materials," "hazardous wastes," "chemicals
known to cause cancer or reproductive toxicity," "radioactive materials," or
other similar designations in the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended, 42 U.S.C. Section 9601 et
seq., the Resource Conservation and Recovery Act, 42 U.S.C. Section 6901 et
seq., the Hazardous Materials Transportation Act, 49 U.S.C. Section 1801 et
seq., 33 U.S.C. Section 1251 et seq., 42 U.S.C. Section 300(f) et seq., 42
U.S.C. 7401 et seq., California Health and Safety Code Section 25249.5 et seq.,
California Water Code Section 13000 et seq., California Health and Safety Code
Section 39000 et seq. and any other governmental statutes, ordinances, rules,
regulations, and precautions adopted pursuant to the preceding laws or other
similar laws, regulations and guidelines now or hereafter in effect. Tenant
shall defend (with counsel approved by Landlord), indemnify and hold Landlord,
its trustees, employees and agents, any entity having a security interest in the
premises or the Building, and its and their employees and agents (collectively,
"Indemnitees") harmless from and against, and reimburse the Indemnitees for, all
 -----------
liabilities, claims, costs, damages, and depreciation of property value,
including all foreseeable and unforeseeable consequential damages, directly or
indirectly arising out of the use, generation, storage, or disposal of Hazardous
Materials by Tenant or any person claiming under Tenant, including, without
limitation, the cost of any required or necessary investigation, monitoring,
repair, cleanup, or detoxification and the preparation of any closure or

                                       6
<PAGE>

other required plans, whether such action is required or necessary prior to or
following the termination of this Lease, as well as penalties, fines and claims
for contribution to the full extent that such action is attributable, directly
or indirectly, to the use, generation, storage, or disposal of Hazardous
Materials by Tenant or any person claiming under Tenant. Neither the consent by
Landlord to the use, generation, storage, or disposal of Hazardous Materials nor
the strict compliance by Tenant with all statutes, laws, ordinances, rules,
regulations, and precautions pertaining to Hazardous Materials shall excuse
Tenant from Tenant's obligation of indemnification set forth above. Tenant's
obligations under this Paragraph 6 shall survive the expiration or termination
of this Lease.

     7.   Utilities.
          ---------

               (a)  Tenant shall pay for all water, sewer, gas, electricity,
heat, cooling, energy, telephone, refuse collection, alarm monitoring services,
and other utility-type services furnished to Tenant or the premises, together
with all related installation or connection charges or deposits. Wherever it is
practical to do so such services shall be separately metered or charged to
Tenant by the provider thereof and paid for directly by Tenant. To the extent
any of the foregoing services are provided by Landlord, Tenant shall reimburse
Landlord for all actual out-of-pocket costs incurred by Landlord in connection
with the provision of such services as billed by the provider thereof based on
Landlord's reasonable estimate of the level of Tenant's use or consumption of
such services. Landlord shall bill Tenant for such services as incurred and
payment shall be made by Tenant within ten (10) days after submittal of
Landlord's statement.

               (b)  Landlord shall not be in default hereunder or be liable for
any damages directly or indirectly resulting therefrom, and there shall not be
any rent abatement, by reason of any interruption or curtailment whatsoever in
utility services which is due to fire, accident, strike, governmental authority,
act of God or other causes beyond the reasonable control of Landlord or any
temporary interruption in such service which is necessary to the making of
alterations, repairs or improvements to the Buildings or any part of it.

     8.   Maintenance, Repairs and Alterations.
          -------------------------------------

               (a)  Subject to the provisions of Paragraph 10 below, and except
for damages caused by Tenant, its agents or invitees, Landlord shall keep in
good condition and repair the foundations and exterior walls and roof of the
Building and all common areas within the Building not leased to tenants. Tenant
expressly waives the benefits of any statute which would otherwise afford Tenant
the right to make repairs at Landlord's expense or to terminate this Lease
because of Landlord's failure to keep the premises or the Building in good
order, condition, and repair. Tenant has the right to seek other remedies at law
against Landlord.

               (b)  Tenant shall, at Tenant's expense, maintain the interior
portion of the premises (including, but not limited to, all plumbing and
electrical connections, outlets and lightbulbs) in good condition and repair. If
Tenant fails to do so, Landlord may, but shall not be required to, enter the
premises and put them in the same condition as upon the commencement of the
Lease term, and Landlord's out-of-pocket costs thereof shall automatically
become due and payable as additional rent. Tenant shall be responsible for the
provision, at its own expense, of appropriate janitorial service for the
premises. Tenant shall also cause to be maintained, at its

                                       7
<PAGE>

expense and in good operating condition and repair, all heat, ventilating, and
air conditioning equipment installed in the premises. Provided Tenant is in
default beyond cure periods, if Landlord so elects, Tenant shall retain the
services of Landlord or a maintenance company retained by it to perform
maintenance of Tenant's heating, ventilating and air conditioning equipment and
shall reimburse Landlord for the cost thereof upon demand. At the expiration of
the term Tenant shall deliver up possession of the premises in good condition
and repair, only ordinary wear and tear excepted.

               (c)  Tenant shall not, without Landlord's prior consent, make any
alterations, improvements, or additions in or about the premises.  In requesting
Landlord's consent, Tenant shall submit to Landlord complete drawings and
specifications describing such work and the identity of the proposed contractor.
As a condition to giving such consent, Landlord may, among other things, require
that Tenant remove any such alterations, improvements or additions at the
expiration of the term, and restore the premises to their prior condition.
Before commencing any work relating to alterations, additions, or improvements
affecting the premises, Tenant shall notify Landlord of the expected date of
commencement thereof and of the anticipated cost thereof, and shall furnish such
information as shall reasonably be requested by Landlord substantiating Tenant's
ability to pay for such work.  Landlord shall then have the right at any time
and from time to time to post and maintain on the premises such notices as
Landlord reasonably deems necessary to protect the premises and Landlord from
mechanics' liens or any other liens.  In any event, Tenant shall pay when due
all claims for labor or materials furnished to or for Tenant at or for use in
the premises.  Tenant shall not permit any mechanics' liens to be levied against
the premises for any labor or materials furnished to Tenant or claimed to have
been furnished to Tenant or to Tenant's agents or contractors in connection with
work of any character performed or claimed to have been performed on the
premises by or at the direction of Tenant.  All alterations, improvements, or
additions in or about the premises performed by or on behalf of Tenant shall be
done in a first-class, workmanlike manner, shall not unreasonably lessen the
value of the leasehold improvements in the premises, and shall be completed in
compliance with all applicable laws, ordinances, regulations, and orders of any
governmental authority having jurisdiction thereover, as well as the
requirements of insurers of the premises and the Building.  Upon Landlord's
request, Tenant shall remove any contractor, subcontractor, or material supplier
from the premises and the Building if the work or presence of such person or
entity results in labor disputes in or about the Building or the Marina Village
Project (the "Project"), or damage to the premises, Building or Project.  Unless
              -------
Landlord requires their removal as set forth above, all alterations,
improvements or additions which may be made on the premises shall become the
property of Landlord and remain upon and be surrendered with the premises at the
expiration of the term; provided, however, that Tenant's machinery, equipment
and trade fixtures, other than any which may be affixed to the premises so that
they cannot be removed without material damage to the premises, shall remain the
property of Tenant and may be removed by Tenant provided further Tenant shall be
responsible for repairing all damage to the premises caused by such removal.

     9.   Insurance and Indemnity.
          -----------------------

               (a)  Tenant shall obtain and maintain during the term of this
Lease comprehensive general liability insurance with combined single limit for
personal injury and property damage in a form and with carriers acceptable to
Landlord in an amount not less than $1,000,000, and

                                       8
<PAGE>

employer's liability and workers' compensation insurance as required by law.
Tenant's comprehensive general liability insurance policy shall be endorsed to
provide that (i) it may not be cancelled or altered in such a manner as
adversely to affect the coverage afforded thereby without thirty (30) days'
prior written notice to Landlord, (ii) Landlord is named as additional insured,
(iii) the insurer acknowledges acceptance of the mutual waiver of claims by
Landlord and Tenant pursuant to subparagraph (b) below, and (iv) such insurance
is primary with respect to Landlord and that any other insurance maintained by
Landlord is excess and noncontributing with such insurance. If, in the opinion
of Landlord's insurance adviser, based on a substantial increase in recovered
liability claims generally, the specified amounts of coverage are no longer
adequate, such coverage shall be appropriately increased. Prior to the
commencement of the term, Tenant shall deliver to Landlord a duplicate of such
policy or a certificate thereof to Landlord for retention by it, with
endorsements, and at least thirty (30) days prior to the expiration of such
policy or any renewal thereof, Tenant shall deliver to Landlord a replacement or
renewal binder, followed by duplicate policy or certificate within a reasonable
time thereafter. If Tenant fails to obtain such insurance or to furnish Landlord
any such duplicate policy or certificate as herein required, Landlord may, at
its election, without notice to Tenant and without any obligation to do so,
procure and maintain such coverage and Tenant shall reimburse Landlord on demand
as additional rent for any premium so paid by Landlord.

               (b)  Landlord hereby waives all claims against Tenant, and
Tenant's officers, directors, partners, employees, agents and representatives
for loss or damage to the extent that such loss or damage is insured against
under any valid and collectible insurance policy insuring Landlord or would have
been insured against but for any deductible amount under any such policy, and
Tenant waives all claims against Landlord including Landlord's officers,
directors, partners, employees, agents, and representatives for loss or damage
to the extent such loss or damage is insured against under any valid and
collectible insurance policy insuring Tenant or required to be maintained by
Tenant under this Lease, or would have been insured against but for any
deductible amount under any such policy.

               (c)  As this Lease does not involve the public interest and
insurance is available to Tenant which will protect it against such claims,
damage, injury or death, Tenant hereby waives all claims against Landlord for
damage to any property or injury to or death of any person in, upon or about the
premises or the Building arising at any time and from any cause. Tenant shall
hold Landlord harmless from and defend Landlord against all claims (except such
as arise from the sole negligence or willful misconduct of Landlord, its agents,
employees or contractors) (i) for damage to any property or injury to or death
of any person arising from the use of the premises by Tenant, or (ii) arising
from the negligence or willful misconduct of Tenant, its employees, agents, or
contractors in, upon or about those portions of the Building, other than the
premises. The foregoing indemnity obligation of Tenant shall include reasonable
attorneys' fees, investigation costs, and all other reasonable costs and
expenses incurred by Landlord from the first notice that any claim or demand is
to be made or may be made. The provisions of this Paragraph 9 shall survive the
termination of this Lease with respect to any damage, injury, or death occurring
prior to such termination.

                                       9
<PAGE>

     10.  Damage or Destruction.
          ---------------------

               (a)  If during the term the premises are totally or partially
destroyed, or any other portion of the Building is damaged in such a way that
Tenant's use of the premises is materially interfered with, from a risk which is
wholly covered by insurance, subject to the availability of insurance proceeds,
Landlord shall proceed with reasonable diligence to repair the damage or
destruction and this Lease shall not be terminated; provided, however, that if
in the opinion of Landlord's architect the work of repair cannot be completed in
one hundred and eighty (180) days Landlord may at its election terminate the
Lease by notice given to Tenant.

               (b)  If during the term the premises are totally or partially
destroyed, or any other portion of the Building is damaged in such away that
Tenant's use of the premises is materially interfered with, from a risk which is
not wholly covered by insurance, Landlord may at its election by notice given to
Tenant restore the premises or terminate this Lease.

               (c)  In case of destruction or damage which materially interferes
with Tenant's use of the premises, if this Lease is not terminated as above
provided, rent shall be abated during the period required for the work of repair
based upon the degree of interference with Tenant's use of the premises. Except
for abatement of rent, Tenant shall have no claim against Landlord for any loss
suffered by Tenant due to damage or destruction of the premises or any work of
repair undertaken as herein provided. Tenant expressly waives the provisions of
Sections 1932 and 1933(4) of the California Civil Code.

     11.  Eminent Domain. If all or any part of the premises shall be taken as a
          --------------
result of the exercise of power of eminent domain, this Lease shall terminate as
to the part so taken as of the date of taking, and in the case of a partial
taking, either Landlord or Tenant shall have the right to terminate this Lease
as to the balance of the premises by notice to the other within thirty (30) days
after such date if the portion of the premises taken shall be of such extent and
nature as substantially to handicap, impede or impair Tenant's use of the
balance of the premises for Tenant's purposes. In the event of any taking,
Landlord shall be entitled to any and all compensation, damages, income, rent,
awards, or any interest therein whatsoever which may be paid or made in
connection therewith, and Tenant shall have no claim against Landlord for the
value of any unexpired term of this Lease or otherwise. In the event of a
partial taking of the premises which does not result in a termination of this
Lease, the monthly rental thereafter to be paid shall be equitably reduced on a
square footage basis. Tenant has the right to seek a separate award.

     12.  Assignment and Subletting.
          -------------------------

               (a)  Tenant shall not assign this Lease or any interest herein or
sublet the premises or any part thereof without the prior consent of Landlord,
which consent shall not be unreasonably withheld; Tenant shall not hypothecate
this Lease or any interest herein or permit the use of the premises by any party
other than Tenant without the prior consent of Landlord, which consent may be
withheld by Landlord in its absolute discretion. This Lease shall not, nor shall
any interest herein, be assignable as to the interest of Tenant by operation of
law without the consent of Landlord. Any of the foregoing acts without such
consent shall be void and shall, at the option of Landlord, terminate this
Lease. In connection with each consent requested by Tenant, Tenant shall submit
to Landlord the terms of the proposed transaction, the identity of the

                                       10
<PAGE>

parties to the transaction, the proposed documentation for the transaction,
current financial statements of any proposed assignee or sublessee and all other
information reasonably requested by Landlord concerning the proposed transaction
and the parties involved therein.

               (b)  Without limiting the other instances in which it may be
reasonable for Landlord to withhold its consent to an assignment or subletting,
Landlord and Tenant acknowledge that it shall be reasonable for Landlord to
withhold its consent in the following instances:

                         (i)   if the proposed assignee or sublessee is a
governmental agency;

                         (ii)  if, in Landlord's reasonable judgment, the use of
the premises by the proposed assignee or sublessee would entail any alterations
which would lessen the value of the leasehold improvements in the premises, or
would require increased services by Landlord;

                         (iii) if, in Landlord's reasonable judgment, the
financial worth of the proposed assignee or sublessee does not meet the credit
standards applied by Landlord for other tenants under leases with comparable
terms;

                         (iv)  in the case of a subletting of less than the
entire premises, if the subletting would result in the division of the premises
into more than two subparcels, would create a subparcel of a configuration that
is not suitable for normal leasing purposes, or would require access to be
provided through space leased or held for lease to another tenant or
improvements to be made outside of the premises; or

                         (v)   if, at the time consent is requested or at any
time prior to the granting of consent, Tenant is in default under the Lease or
would be in default under the Lease but for the pendency of any grace or cure
period under Paragraph 13 below.

               (c)  If at any time or from time to time during the term of this
Lease Tenant desires to sublet all or any part of the premises, Tenant shall
give notice to Landlord setting forth the terms of the proposed subletting and
the space so proposed to be sublet. Landlord shall have the option, exercisable
by notice given to Tenant within twenty (20) days after Tenant's notice is
given, either to sublet from Tenant such space at the rental and other terms set
forth in Tenant's notice, or, if the proposed subletting is for the entire
premises for a sublet term ending within the last year of the term of this
Lease, to terminate this Lease. If Landlord does not exercise such option,
Tenant shall be free to sublet such space to any third party on the same terms
set forth in the notice given to Landlord, subject to obtaining Landlord's prior
consent as herein above provided.

               (d)  As used in this Paragraph 12, the term, "assign" or
                                                             ------
"assignment" shall include, without limitation, any sale, transfer, or other
 ----------
disposition of all or any position of Tenant's estate under this Lease, whether
voluntary or involuntary, and whether by operation of law or otherwise
including, any of the following:

                         (i)   If Tenant is a corporation: (A) any dissolution,
merger, consolidation, or other reorganization of Tenant or (B) a sale of more
than fifty percent (50%) of the value of the assets of Tenant or (C) if Tenant
is a corporation with fewer than 500

                                       11
<PAGE>

shareholders, sale or other transfer of a controlling percentage of the capital
stock of Tenant. The phrase "controlling percentage" means the ownership of, and
                             ----------------------
the right to vote, stocks possessing at least fifty percent (50%) of the total
combined voting power of all classes of Tenant's stock issues, outstanding and
permitted to vote for the election of directors;

                         (ii)  If Tenant is a trust the transfer of more than
fifty percent (50%) of the beneficial interest of Tenant, or the dissolution of
the trust;

                         (iii) If Tenant is a partnership or joint venture, the
withdrawal, or the transfer of the interest of any general partner or joint
venturer or the dissolution of the partnership or joint venture;

                         (iv)  If Tenant is composed of tenants-in-common, the
transfer of interest of any cotenants or the partition or dissolution of the
cotenancy.

               (e)  No sublessee (other than Landlord if it exercises its option
pursuant to subparagraph (c) above) shall have a right further to sublet, and
any assignment by a sublessee of its sublease shall be subject to Landlord's
prior consent in the same manner as if Tenant were entering into a new sublease.

               (f)  In the case of an assignment, one half of all sums or other
economic consideration received by Tenant as a result of such assignment shall
be paid to Landlord. In the event such consideration is received by Tenant in
installments, the portion of each installment to be paid to Landlord shall be
determined by multiplying the installment by a fraction, the numerator of which
is the total amount of the foregoing permitted deductions and the denominator of
which is the total consideration receivable by Tenant as a result of such
assignment.

               (g)  In the case of a subletting, one half of all sums or
economic consideration received by Tenant as a result of such subletting shall
be paid to Landlord after first deducting (i) the rental due hereunder, prorated
to reflect only rental allocable to the sublet portion of the premises, (ii) the
cost of leasehold improvements made to the sublet portion of the premises at
Tenant's cost, amortized over the term of this Lease except for leasehold
improvements made for the specific benefit of the sublessee, which shall be
amortized over the term of the sublease, and (iii) the cost of any real estate
commissions incurred in connection with such subletting, amortized over the term
of the sublease.

               (h)  Regardless of Landlord's consent, no subletting or
assignment shall release Tenant of Tenant's obligation or alter the primary
liability of Tenant to pay the rental and to perform all other obligations to be
performed by Tenant hereunder. The acceptance of rental by Landlord from any
other person shall not be deemed to be a waiver by Landlord of any provision
hereof Consent to one assignment or subletting shall not be deemed consent to
any subsequent assignment or subletting. In the event of default by any assignee
of Tenant or any successor of Tenant in the performance of any of the teems
hereof, Landlord may proceed directly against Tenant without the necessity of
exhausting remedies against such assignee or successor. Landlord may consent to
subsequent assignments or subletting of this Lease or amendments or
modifications to this Lease with assignees of Tenant, without notifying Tenant,
or any successor

                                       12
<PAGE>

of Tenant, and without obtaining its or their consent thereto and such action
shall not relieve Tenant of liability under this Lease.

               (i)  In the event Tenant shall assign or sublet the premises or
request the consent of Landlord to any assignment or subletting or if Tenant
shall request the consent of Landlord for any act that Tenant proposes to do,
then Tenant shall pay Landlord's reasonable attorneys' fees incurred in
connection therewith.

     13.  Default by Tenant.
          -----------------

               (a)  The following events shall constitute events of default
under this Lease:

                    (i)   a default by Tenant in the payment of any rent or
other sum payable hereunder for a period of three (3) days after the same is
due;

                    (ii)  a default by Tenant in the performance of any of the
other terms, covenants, agreements, or conditions contained herein and, if the
default is curable, the continuation of such default for a period of ten (10)
days after notice by Landlord or beyond the time reasonably necessary for cure
if the default is of the nature to require more than ten (10) days to remedy,
provided that if Tenant has defaulted in the performance of the same obligation
one or more times in any twelve-month period and notice of such default has been
given by Landlord in each instance, no cure period shall thereafter be
applicable hereunder;

                    (iii) the bankruptcy or insolvency of Tenant, any transfer
by Tenant in fraud of creditors, assignment by Tenant for the benefit of
creditors, or the commencement of any proceedings of any kind by or against
Tenant under any provision of the Federal Bankruptcy Act or under any other
insolvency, bankruptcy or reorganization act unless, in the event any such
proceedings are involuntary, Tenant is discharged from the same within sixty
(60) days thereafter; the appointment of a receiver for a substantial part of
the assets of Tenant; or the levy upon this Lease or any estate of Tenant
hereunder by any attachment or execution;

                    (iv)  the abandonment of the premises; and

                    (v)   a default by Tenant in the performance of any of the
terms, covenants, agreements, or conditions contained in any other lease or
agreement between Landlord and Tenant, including that certain Net Office-Tech
Lease dated as of January 15, 1998 between Landlord and Tenant for premises
located at 860 Atlantic Avenue, Alameda, California.

          (b)  Upon the occurrence of any event of default by Tenant hereunder,
Landlord may, at its option and without any further notice or demand.  in
addition to any other rights and remedies given hereunder or by law, do any of
the following:

                    (i)   Landlord shall have the right, so long as such default
continues, to give notice of termination to Tenant, and on the date specified in
such notice this Lease shall terminate.

                    (ii)  In the event of any such termination of this Lease,
Landlord may then or at any time thereafter, reenter the premises and remove
therefrom all persons and

                                       13
<PAGE>

property and again repossess and enjoy the premises, without prejudice to any
other remedies that Landlord may have by reason of Tenant's default or of such
termination.

                    (iii) In the event of any such termination of this Lease,
and in addition to any other rights and remedies Landlord may have, Landlord
shall have all of the rights and remedies of a landlord provided by Section
1951.2 of the California Civil Code. The amount of damages which Landlord may
recover in event of such termination shall include, without limitation, (i) the
worth at the time of award (computed by discounting such amount at the discount
rate of the Federal Reserve Bank of San Francisco at the time of award plus one
percent) of the amount by which the unpaid rent for balance of the term after
the time of award exceeds the amount of rental loss that Tenant proves could be
reasonably avoided, (ii) all reasonable legal expenses and other related costs
incurred by Landlord following Tenant's default, (iii) all costs incurred by
Landlord in restoring the premises to good order and condition, or in
remodeling, renovating or otherwise preparing the premises for reletting, and
(iv) all costs (including, without limitation, any brokerage commissions)
incurred by Landlord in reletting the premises.

                    (iv)  For the purpose of determining the unpaid rent in the
event of a termination of this Lease, or the rent due hereunder in the event of
a reletting of the premises, the monthly rent reserved in this Lease shall be
deemed to be the sum of the rental due under Paragraph 3 above and the amounts
last payable by Tenant pursuant to Paragraph 4 above.

                    (v)   After terminating this Lease, Landlord may remove any
and all personal property located in the premises and place such property in a
public or private warehouse or elsewhere at the sole cost and expense of Tenant.

          (c)  Even though Tenant has breached this Lease and abandoned the
premises, this Lease shall continue in effect for so long as Landlord does not
terminate Tenant's right to possession, and Landlord may enforce all its rights
and remedies under this Lease, including the right to recover rental as it
becomes due under this Lease. Acts of maintenance or preservation, efforts to
relet the premises, or the appointment of a receiver upon initiative of Landlord
to protect Landlord's interest under this Lease, shall not constitute a
termination of Tenant's right to possession.

          (d)  The remedies provided for in this Lease are in addition to any
other remedies available to Landlord at law or in equity, by statute or
otherwise.

     14.  Default by Landlord. Landlord shall not be in default unless Landlord
          -------------------
fails to perform obligations required of Landlord hereunder within a reasonable
time, but in no event later than thirty (30) days after notice by Tenant to
Landlord specifying wherein Landlord has failed to perform such obligation;
provided, however, that if the nature of Landlord's obligation is such that more
than thirty (30) days are required for performance, then Landlord shall not be
in default if Landlord commences performance within such 30-day period and
thereafter diligently prosecutes the same to completion.

     15.  Security Deposit. On execution of this Lease Tenant shall deposit with
          ----------------
Landlord the sum specified in the Basic Lease Information (the "Deposit").  The
                                                                -------
Deposit shall be held by Landlord as security for the performance by Tenant of
all of the provisions of this Lease.  If

                                       14
<PAGE>

Tenant fails to pay rent or other charges due hereunder, or otherwise defaults
with respect to any provisions of this Lease, Landlord may use, apply, or retain
all or any portion of the Deposit for the payment of any rent or other charge in
default, or the payment of any other sum to which Landlord may become obligated
by reason of Tenant's default, or to compensate Landlord for any loss or damage
which Landlord may suffer thereby. If Landlord so uses or applies all or any
portion of the Deposit, then within ten (10) days after demand therefor Tenant
shall Deposit cash with Landlord in an amount sufficient to restore the Deposit
to the full amount thereof, and Tenant's failure to do so shall be a material
breach of this Lease. Landlord shall not be required to keep the Deposit
separate from its general accounts. If Tenant performs all of Tenant's
obligations hereunder, the Deposit, or so much thereof as has not theretofore
been applied by Landlord, shall be returned, without payment of interest for its
use, to Tenant (or, at Landlord's option, to the last assignee, if any, of
Tenant's interest hereunder) at the expiration of the term hereof, and after
Tenant has vacated the premises. No trust relationship is created herein between
Landlord and Tenant with respect to the Deposit.

     16.  Estoppel Certificate.
          --------------------

               (a)  Tenant shall at any time upon not more than ten (10) days'
prior notice from Landlord execute, acknowledge and deliver to Landlord a
statement certifying (i) 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) (ii) the date to
which the rent, security deposit, and other sums payable hereunder have been
paid, (iii) acknowledging that there are not, to Tenant's knowledge, any uncured
defaults on the part of Landlord hereunder, or specifying such defaults, if any,
which are claimed, and (iv) such other matters as may reasonably be requested by
Landlord. Any such statement may be conclusively relied upon by any prospective
purchaser or encumbrancer of the Building.

               (b)  Tenant's failure to deliver such statement within such time
shall be conclusive upon Tenant, (i) that this Lease is in full force and
effect, without modification except as may be represented by Landlord, (ii) that
there are no uncured defaults in Landlord's performance, and (iii) that not more
than one month's rent has been paid in advance.

               (c)  If the Landlord desires to finance or refinance the
Building, Tenant agrees to deliver to any lender designated by Landlord such
financial statements of Tenant as may be reasonably required by such lender. All
such financial statements shall be received by Landlord in confidence and shall
be used for the purposes herein set forth.

     17.  Subordination. This Lease, at Landlord's option, shall subordinate to
          -------------
any ground lease, first mortgage, deed of trust, or any other hypothecation for
security now or hereafter placed upon the Building and to any and all advances
made on the security thereof and to all renewals, modifications, consolidations,
replacements and extensions thereof. Notwithstanding such subordination,
Tenant's right to quiet possession of the premises shall not be disturbed if
Tenant is not in default and so long as Tenant shall pay the rent and observe
and perform all of the provisions of this Lease, unless this Lease is otherwise
terminated pursuant to its terms. If any first mortgagee, trustee, or ground
lessor shall elect to have this Lease prior to the lien of its first mortgage,
deed of trust or ground lease, and shall give notice thereof to Tenant, this
Lease shall be deemed prior to such first mortgage, deed of trust, or ground
lease, whether this Lease is dated prior to or subsequent to the date of said
first mortgage, deed of trust or ground lease or the

                                       15
<PAGE>

date of recording thereof. If any first mortgage or deed of trust to which this
Lease is subordinate is foreclosed or a deed in lieu of foreclosure is given to
the first mortgagee or beneficiary, Tenant shall attorn to the purchaser at the
foreclosure sale or to the grantee under the deed in lieu of foreclosure; if any
ground lease to which this Lease is subordinate is terminated, Tenant shall
attorn to the ground lessor. Tenant agrees to execute any documents required to
effectuate such subordination or to make this Lease prior to the lien of any
first mortgage, deed of trust or ground lease, as the case may be, or to
evidence such attornment.

     18.  Attorneys' Fees. If, as a result of any breach or default in the
          ---------------
performance of any of the provisions of this Lease, Landlord uses the services
of any attorney in order to secure compliance with such provisions or recovered
damages therefor, or to terminate this Lease or evict Tenant, Tenant shall
reimburse Landlord for any and all attorneys' fees and expenses in such amount
as the court may adjudge reasonable, provided that if Tenant shall be the
prevailing party in any legal action brought by Landlord against Tenant, Tenant
will be entitled to recover any and all attorneys' fees and expenses in such
amount as the court may adjudge reasonable.

     19.  Non-Discrimination. Tenant covenants for itself; its heirs, executors,
          ------------------
administrators, and assigns, and all persons claiming under or through it, and
this Lease is made and accepted upon it subject to the condition that there
shall be no discrimination against or segregation of any person or group of
persons, on account of race. color, creed. religion, sex, marital status,
national origin, or ancestry in the leasing, subleasing, transferring, use,
occupancy, tenure, or enjoyment of the premises herein leased nor shall the
Tenant itself, or any person claiming under or through it, establish or permit
any such practice or practices of discrimination or segregation with reference
to the selection, location, number, use, or occupancy of tenants, subtenants, or
vendees in the premises.

     20.  Notices. All notices, consents, demands, and other communications from
          -------
one party to the other given pursuant to the terms of this Lease shall be in
writing and shall be deemed to have been fully given when deposited in the
United States mail, certified or registered, postage prepaid, and addressed as
follows: to Tenant at the address specified in the Basic Lease Information or to
such other place as Tenant may from time to time designate in a notice to
Landlord: or, to Landlord at the address specified in the Basic Lease
Information, or to such other place and with such other copies as Landlord may
from time to time designate in a notice to Tenant.

     21.  General Provisions.
          -------------------

               (a)  This Lease shall be governed by and construed in accordance
with the laws of the state of California.

               (b)  The invalidity of any provision of this Lease, as determined
by a court of competent jurisdiction, shall in no way affect the validity of any
other provision hereof

               (c)  This Lease contains all agreements of the parties with
respect to any matter mentioned herein and only may be modified in writing
signed by the parties.

               (d)  No waiver by Landlord of any provision hereof shall be
deemed a waiver of any other provision or of any subsequent breach by Tenant of
the same or any other provision. Landlord's consent to or approval of any act
shall not be deemed to render unnecessary the

                                       16
<PAGE>

obtaining of Landlord's consent to or approval of any subsequent act by Tenant.
The acceptance of rent hereunder by Landlord shall not be a waiver of any
preceding breach by Tenant of any provision hereof, other than the failure of
Tenant to pay the particular rent accepted, regardless of Landlord's knowledge
of such preceding breach at the time of acceptance of such rent.

               (e)  If Tenant remains in possession of the premises or any part
thereof after the expiration of the term with the consent of Landlord, such
occupancy shall be a tenancy from month to month at a rental in the amount of
two times the last month's rental during the term, plus all other charges
payable hereunder, and upon all of the terms hereof.

               (f)  Subject to the provisions of this Lease restricting
assignment or subletting by Tenant, this Lease shall bind the parties, their
personal representatives, successors, and assigns.

               (g)  Landlord and Landlord's agents shall have the right to enter
the premises at reasonable times for the purpose of inspecting the same, showing
the same to prospective purchasers, tenants, lenders and other interested
parties, and making such alterations, repairs, improvements, or additions to the
premises or to the Building as Landlord may deem necessary or desirable.
Landlord may at any time during the last one hundred twenty (120) days of the
term place on or about the premises any ordinary "For Lease" sign. Landlord's
access shall be subject to Tenant's security procedures, except in emergencies.

               (h)  Tenant shall not conduct any auction at the premises without
Landlord's prior consent.

               (i)  The voluntary or other surrender of this Lease by Tenant,
the mutual cancellation thereof or the termination of this Lease by Landlord as
a result of Tenant's default shall, at the option of Landlord, terminate all or
any existing subtenancies or may, at the option of Landlord, operate as an
assignment to Landlord of any or all of such subtenancies.

               (j)  If Tenant is a corporation, each individual executing this
Lease on behalf of Tenant represents and warrants that he is duly, authorized to
execute and deliver this Lease on behalf of the corporation in accordance with a
duly adopted resolution of the Board of Directors and that this Lease is binding
upon the corporation in accordance with its terms.

               (k)  The term "Landlord" as used herein means the then owner of
                              --------
the Building and in the event of a sale of the Building the selling owner shall
be automatically relieved of all obligations of Landlord hereunder, except for
acts or omissions of Landlord theretofore occurring.

               (l)  The term "day" as used herein means a calendar day.
                              ---

               (m)  The obligations of Landlord under this Lease do not
constitute personal obligations of the partners, directors, officers,
shareholders, or trustees of Landlord, Tenant shall look solely to Landlord and
its assets for the realization of any claims against Landlord and not to the
assets of any of the partners of Landlord, and Tenant expressly waives any and
all right to proceed against any of its partners or the officers, directors,
trustees, shareholders, agents, or employees of any of such partners, except to
the extent of their interest in Landlord.

                                       17
<PAGE>

               (n)  On request by Landlord, Tenant shall furnish Landlord with
satisfactory evidence of payment of Tenant's business personal property taxes
pertaining to the premises and deliver copies of such business personal property
tax bills to Landlord.

     22.  Exhibits. The exhibits and addendum, if any, specified in the Basic
          --------
Lease Information are attached to this Lease and by this reference made a part
hereof.

     IN WITNESS WHEREOF, the parties have executed this Lease on the respective
dates indicated below.

TENANT:                         LANDLORD:

XENOGEN CORPORATION,            ALAMEDA REAL ESTATE INVESTMENTS,
a California corporation        a California limited partnership

                                By:  Vintage Alameda Investments, LP
By: /s/ Pamela Reilly Contag         a California limited partnership
   -------------------------         operating general partner
Name:   Pamela Reilly Contag
     -----------------------         By:  Vintage Properties-Alameda Commercial,
Title:  CEO and President                 a California corporation,
      ----------------------              managing general partner

By:                                       By: /s/ Joseph R. Seiger
   -------------------------                 ---------------------------------
Name:                                     Name:   Joseph R. Seiger
     -----------------------                   -------------------------------
Title:                                    Title:  President
      ----------------------                    ------------------------------

Date of Execution                         Date of Execution
by Tenant:________________                by Landlord:________________________

                                       18
<PAGE>

                                   EXHIBIT B
                                   ---------

                                 MARINA VILLAGE

                      INITIAL IMPROVEMENT OF THE PREMISES.

     1.   If, within sixty (60) days following the commencement of the term,
Tenant discovers that any portion of the plumbing, heating, ventilating and air-
conditioning system serving the premises which plumbing and other systems are
necessary for the occupancy of the premises for normal office (as opposed to
fume hoods, animal storage, manufacturing or other special purposes) are not in
good working order and condition, it may so notify Landlord and Landlord shall
thereafter promptly cause such plumbing and other systems to be placed in good
operating condition and repair.

     2.   (a)  Landlord shall reimburse Tenant for up to $106,485 (the "TI
                                                                        --
Allowance") for its out-of-pocket costs incurred in replacing existing carpeting
---------
in the premises, painting the interior of the premises and for making other
alterations and improvements within the premises (the "Tenant Improvements");
                                                       -------------------
provided, however, that no portion of the TI Allowance will be funded by
Landlord with respect to the portion of the premises that is Suite 103 prior to
September 15, 2000 and only if the Deposit has been timely increased by Tenant
in accordance with requirements of Paragraph 15 of the Lease.  No portion of the
TI Allowance may be applied to pay for the costs of millwork or cabinetry which
may be removed by Tenant at the end of the term, furniture or trade equipment or
trade fixtures.  All alterations and improvements within the Premises shall be
subject to the requirements of Paragraph 8(c) of the Lease.  Landlord shall also
reimburse Tenant, and not as part of the TI Allowance for costs incurred by
Tenant in connection with the Tenant Improvements to remove Hazardous Materials
from the premises existing as of the commencement of the term.

          (b)  Landlord shall reimburse Tenant for its out-of-pocket costs
incurred in connection with Tenant Improvements within thirty (30) days of
Tenant's request provided that at the time of such payment:

               (i)   Tenant has delivered to Landlord copies of building permits
issued in connection with the Tenant Improvements indicating final inspection
has been approved;

               (ii)  Tenant has delivered to Landlord unconditional waivers and
releases of lien from all parties have established a right to lien, or evidence
that all applicable limitation periods for the filing of mechanics liens have
expired without any such liens having been filed;

               (iii) Tenant is not then in default under the Lease; and

               (iv)  Tenant delivering copies of invoices and other evidence,
reasonably acceptable to Landlord of costs incurred by Tenant.

                                       19
<PAGE>

                                  ADDENDUM TO
                                 MARINA VILLAGE
                            NET OFFICE - TECH LEASE

     THIS ADDENDUM TO MARINA VILLAGE NET OFFICE - TECH LEASE ("Addendum") shall
                                                               --------
constitute part of that certain Marina Village Net Office - Tech Lease dated as
of June 6, 2000 ("Lease") by and between ALAMEDA REAL ESTATE INVESTMENTS, a
                  -----
California limited partnership ("Landlord") and XENOGEN CORPORATION, a
                                 --------
California corporation ("Tenant"), for Premises identified as 2061 Challenger
                         ------
Drive, Suites 100, 101 and 103, Alameda, California, and the terms hereof shall
for all purposes be considered part of the Lease and supersede any provisions of
the Lease to the contrary.

     1.   Amendment of Paragraph 1:  Premises.  The following language is hereby
          -------------------------
added at the end of Paragraph 1 of the Lease:

               "During the term, Tenant shall have the right to use, on a non-
               exclusive basis and at no additional charge, automobile parking
               at the rate of a minimum of 3.4 spaces per 1,000 square feet of
               net rentable area of the premises. In addition, Tenant may
               install, at Tenant's expense, exterior signage identifying Tenant
               on the Building in compliance with the Marina Village signage
               program. Tenant acknowledges that two of the suites constituting
               the Premises are expected to be delivered to Tenant on the
               following dates: Suite 100 (approximately 13, 088 rsf) on
               November 1, 2000; and Suite 101 (approximately 5,329 rsf) on
               February 28, 2001. The foregoing expected delivery dates
               correspond with the termination dates of the leases with the
               current occupants within such suites. Landlord shall use
               commercially reasonable efforts to deliver such suites on such
               dates, but Tenant acknowledges that such delivery dates are
               subject to the vacation of the premises by the existing tenants.
               Tenant acknowledges and agrees that the actual delivery dates and
               availability of each suite for occupancy hereunder by Tenant may
               be delayed or accelerated based on factors beyond Landlord's
               control. In the event of a delay in delivery, rent for such suite
               shall abate until delivery shall have occurred. In the event that
               any part of the Premises has not been delivered to Tenant on or
               before July 1, 2001 for any reason whatsoever, then Tenant, by
               notice to Landlord prior to full delivery of the Premises, may
               terminate this Lease as to such part of the Premises not so
               delivered. Tenant agrees to accept delivery of each of the
               foregoing suites upon thirty (30) days' notice from Landlord.

     2.   Amendment of Paragraph 2: Term.
          ------------------------------

               (a)  The first sentence of Paragraph 2(a) is hereby deleted and
the following language is substituted in its place:

               "(a) The term of this Lease shall commence and, unless sooner
               terminated as hereinafter provided, shall end on the dates
               respectively specified in the Basic Lease Information, subject to
               Tenant's right to elect to have the term commence prior to June
               15, 2000."

                                       20
<PAGE>

               (b)  Paragraph 2(b) is hereby deleted and the following language
is substituted in its place:

               "(b) Tenant shall complete any Tenant Improvements to be
               constructed or installed in the Premises pursuant to Exhibit B
                                                                    ---------
               attached hereto. Tenant acknowledges and agrees that Landlord has
               no obligation to make any alterations or improvements to the
               Premises hereunder."

     3.   Amendment of Paragraph 3:  Rent.
          --------------------------------

               (a)  The third sentence of Paragraph 3(c) of the Lease is hereby
deleted and the following language is substituted in its place:

               "Accordingly, if any installments of rent or any other sums due
               from Tenant shall not be received by Landlord within three (3)
               days following the date due, then Tenant shall pay to Landlord a
               late charge equal to six percent (6%) of such overdue amount."

               (b)  The first sentence of Paragraph 3(d) of Lease is hereby
deleted and the following language is substituted in its place:

               "Any amount due to Landlord, if not paid when due, shall bear
               interest from the date due until the date paid at the rate of ten
               percent (10%) per annum."

     4.   Amendment of Paragraph 4:  Taxes and Operating Expenses.
          -------------------------------------------------------

               (a)  The following language is hereby added to the end of
Paragraph 4(a) of the Lease:

               "Notwithstanding the foregoing, "Property Taxes" shall not
                                                --------------
               include and Tenant shall not be required to pay any portion of
               any tax or assessment expense or any increase therein: (i) in
               excess of any installment of an assessment which otherwise would
               be required to be paid at such time; (ii) attributable to
               Landlord's net income, inheritance, gift, transfer, estate or
               estate income taxes; or (iii) the improvement of any portion of
               the Building for the sole use of other occupants not claiming
               under Tenant. "Operating Expenses" shall not include and Tenant
                              ------------------
               shall not have any obligation to perform or to pay for any of the
               following: (A) costs to operate, maintain or repair occasioned by
               the willful misconduct, gross negligence or action in violation
               of law by Landlord, its agents, employees or contractors; (B)
               costs of repair or replacement occasioned by casualty, other than
               deductibles for insured casualties other than earthquakes, or by
               the exercise of the power of eminent domain; (C) costs to correct
               any construction defect in the Building or law applicable to the
               Building as of the commencement of the term other than as
               occasioned by alterations or improvements made by or for Tenant;
               (D) costs incurred in connection with the presence of any
               Hazardous Materials as of the commencement of the term; (E)
               interest, charges and fees incurred on debts, other than
               assessments, or debt incurred in connection with the financing of
               Items which are permitted to be charged as Operating Expenses; or

                                       21
<PAGE>

               (F) costs which could properly be capitalized under generally-
               accepted accounting principles, except to the extent amortized
               over the useful life of the Item in question. Operating Costs
               shall only include the deductible amount for the repair or
               reconstruction of casualties covered by earthquake insurance in
               an amount not to exceed $50,000 (the "Earthquake Limit"), if the
                                                     ----------------
               casualty occurs during the first twelve (12) months of the term
               or during the first twelve (12) months of an Option Period (as
               defined in Paragraph 17 of the Addendum to this Lease), with the
               Earthquake Limit being reduced by $5,000 during each 12-month
               period thereafter. In addition, Operating Costs shall only
               include premiums for earthquake insurance in an amount not in
               excess of four (4) times the then-market rate premium for
               standard all-risk casualty insurance on the same property. In
               addition, Property Taxes and Operating Expenses shall be pro
               rated for any partial year in which the term shall commence or
               end. Any annual increase in property management fees which are
               included as Operating Expenses shall be limited to three percent
               (3%) of the amount incurred in the prior year."

               (b)  The third sentence of Paragraph 4(c). of the Lease is hereby
deleted and the following language is substituted in its place:

               "If on the basis of such statement, Tenant owes an amount that is
               less than the estimated payments for such calendar year
               previously made by Tenant, Landlord shall refund such excess to
               Tenant within thirty (30) days following delivery of such
               statement to Tenant."

     5.   Amendment of Paragraph 5.  The following language is  hereby added to
          ------------------------
paragraph 5 of the Lease, to read as follows:

               "At Tenant's request, and at no out of pocket cost to Landlord,
               Landlord shall cooperate with Tenant in any protest by Tenant of
               the assessment of property owned by, or improvements to the
               premises made by, Tenant."

     6.   Amendment of Paragraph 6:  Use.
          ------------------------------

               (a)  The third and fourth sentences of Paragraph 6(b) of the
Lease are hereby deleted and the following language is substituted in its place:

               "Tenant shall not cause, or allow anyone else to cause, any
               Hazardous Materials to be used, generated, stored or disposed of
               on or about the Premises or the Building in violation of any laws
               or regulations related to Hazardous Materials. Tenant shall
               defend (with counsel approved by Landlord) indemnify and hold
               Landlord, its and their partners, employees and agents and any
               entity having a security interest in the premises or the Building
               and its and their employees and agents (collectively,
               "Indemnitees") harmless from and against, and reimburse the
                -----------
               Indemnitees for, all liabilities, claims, costs, damages, and
               depreciation of property value, including foreseeable and
               unforeseeable consequential damages, directly or indirectly
               arising out of the use, generation, storage or disposal of
               Hazardous Materials by Tenant or any person employed by or under
               the control of

                                       22
<PAGE>

               Tenant, including without limitation, the cost of any required or
               necessary investigation, monitoring, repair, clean-up or
               detoxification and the preparation of any closure or other
               required plans, whether such action is required or necessary
               prior to or following termination or expiration of this Lease, as
               well as penalties, fines and claims for contribution to the full
               extent that such action is attributable, directly or indirectly,
               to the use, generation, storage or disposal of Hazardous
               Materials by Tenant or any person employed by or under the
               control of Tenant. In no event shall Tenant be liable to any of
               the Indemnities for the use, generation, storage or disposal of
               Hazardous Materials not caused by or resulting from Tenant or any
               person employed by or under the control of Tenant."

               (b)  The following language is hereby added as Paragraph 6(d) of
               the Lease:

               "(d) Notwithstanding anything in this Lease to the contrary,
               Tenant shall not be required to comply with or cause the premises
               to comply with any laws, rules or regulations regarding
               alterations or improvements unless compliance with any of the
               foregoing is necessitated solely due to the particular nature of
               Tenant's occupancy or Tenant's particular use of the Premises or
               in connection with any improvements or alterations to the
               Premises made by or for Tenant or those under its control."

     7.   Amendment of Paragraph 8:  Maintenance, Repairs and Alterations.  The
          ---------------------------------------------------------------
following language is hereby added at the end of Paragraph 8(b) of the Lease:

               "Tenant's obligations with respect to the maintenance of all
               heat, ventilating and air conditioning equipment installed in the
               premises shall extend to all trade fixtures and equipment which
               exist in the premises as of the commencement of the term. Tenant
               shall only pay for the costs of replacement of all or portions of
               the heating, ventilating and air conditioning system serving the
               premises or capital expenditures which are otherwise properly
               included as Operating Expenses and are amortized over the useful
               life of the item in question, together with interest at the prime
               or reference rate announced from time-to-time in the Wall Street
               Journal for short-term commercial loans, plus two percent (2%)
               per annum. Tenant's obligation to maintain trade fixtures and
               equipment in the premises as of the commencement of the term
               shall be limited to maintaining such trade fixtures and equipment
               in their condition and repair as of the commencement of the term.
               Further, Tenant's obligations with respect to the surrender of
               the premises shall be fulfilled if Tenant surrenders possession
               of the premises in the condition existing as of the commencement
               of the term, acts of God, casualties, condemnation, Hazardous
               Materials (other than those released, stored, emitted by Tenant),
               and alterations or other interior improvements which may be
               surrendered as of the end of the Lease, excepted."

     8.   Amendment of Paragraph 9:  Insurance and Indemnity.
          --------------------------------------------------

               (a)  The following language is hereby added at the end of
Paragraph 9(a) of the Lease:

                                       23
<PAGE>

               "Landlord shall maintain "all risk" property insurance insuring
               against risk of loss or damage to the Building for the full
               replacement cost thereof."

               (b)  The first clause of the first sentence of Paragraph 9(b) of
the Lease is hereby deleted and the following language is substituted in its
place:

               "(b) Notwithstanding anything in the Lease and without regard to
               the negligence or misconduct of the party to be released,
               Landlord hereby waives all claims against Tenant and Tenant's
               officers, directors, partners, employees, agents and
               representatives, for loss or damage to the extent that such loss
               or damage is insured against under any valid and collectible
               insurance policy insuring Landlord or required to be maintained
               by Landlord under this Lease, or would have been insured against
               but for any deductible amount under any such policy,"

               (c) The first phrase of the second sentence of Paragraph 9(c) of
the Lease is hereby deleted and the following language is substituted in its
place:

               "Tenant shall hold Landlord harmless from and defend Landlord
               against all claims (except such as arise from the gross
               negligence or willful misconduct of Landlord, its agents,
               employees or contractors)"

     9.   Amendment of Paragraph 10:  Damage or Destruction.
          -------------------------------------------------

               (a)  The final clause of Paragraph 10(a) of the Lease is hereby
deleted and the following language is substituted in its place:

               "provided, however, that if in the opinion of Landlord's
               architect the work of repair cannot be completed within one
               hundred and eighty (180) days, Landlord may at its election,
               terminate the Lease by notice given to Tenant."

          (b)  The following language is hereby added at the end of Paragraph
10(b) of the Lease:

               "If the premises are totally or partially destroyed and Landlord
               does not elect to terminate the Lease or is not entitled to
               terminate the Lease pursuant to its terms, then Tenant shall have
               the option to terminate the Lease if the premises cannot be
               restored within three hundred and sixty (360) days after the
               damage, by notice to Landlord given within fifteen (15) days
               following Landlord's notice to Tenant regarding the estimated
               time of repair. In addition, Tenant may terminate the Lease if
               such restoration or repair is not, in fact, substantially
               completed within three hundred and sixty (360) days following the
               event, by notice given to Landlord within fifteen (15) days after
               the end of such 360-day period but prior to such substantial
               completion. Notwithstanding anything in this Paragraph 10 to the
               contrary, Landlord shall not have the right to terminate the
               Lease if the total cost of repair or restoration is estimated to
               cost less than five percent (5%) of the replacement cost of the
               Building, excluding trade fixtures installed by Tenant."

                                       24
<PAGE>

     10.  Amendment of Paragraph 11:  Eminent Domain.  The following language is
          ------------------------------------------
hereby added at the end of Paragraph 11 of the Lease:

               "Notwithstanding the foregoing, Tenant shall be entitled to
               separately claim and prove, but not at the expense of the award
               otherwise payable to Landlord: (a) the unamortized value,
               allocable to the remainder of the term, of any improvements
               installed at Tenant's expense which are not removable; (b)
               Tenant's moving costs; (c) loss to Tenant's goodwill as a
               consequence of the condemnation; and (d) Tenant's trade
               fixtures."

     11.  Amendment of Paragraph 12:  Assignment and Subletting.
          -----------------------------------------------------

               (a)  The second clause of the first sentence of Paragraph 12(a)
of the Lease is hereby deleted and the following language is substituted in its
place:

               "Tenant shall not hypothecate this Lease or any interest herein
               or permit the use of the Premises by any party other than Tenant
               without the prior consent of Landlord, which consent may be
               withheld by Landlord in its reasonable discretion."

               (b)  The following language is hereby added at the end of
Paragraph 12(a) of the Lease:

               "Notwithstanding the foregoing, Tenant may, upon prior notice to
               Landlord accompanied by an explicit assumption of the Tenant's
               obligations under this Lease for the benefit of Landlord, but
               without Landlord's prior consent, sublet the premises or assign
               its interest in this Lease to (i) a subsidiary affiliate,
               division, or corporation controlling, controlled by or under
               common control with Tenant, (ii) a successor corporation related
               to Tenant by merger, consolidation, non-bankruptcy reorganization
               or government action, or (iii) a purchaser of substantially all
               of Tenant's assets as a going concern. A sale or transfer of
               Tenant's capital stock shall not be deemed an assignment,
               subletting or any other transfer of its interest in the Lease or
               in the premises; provided, however, that in the case of such
               purchase of Tenant's assets, the assignee has a tangible net
               worth at least equal to that of Tenant as of the commencement of
               the term."

               (c)  Paragraph 12(b)(4) of the Lease is hereby deleted in its
entirety.

               (d)  Paragraph 12(d)(1) of the Lease is hereby deleted in its
entirety.

               (e)  The first sentence of Paragraph 12(f) of the Lease is hereby
deleted and the following language is substituted in its place:

               "In the case of an assignment, one-half (1/2) of all sums or
               other economic consideration received by Tenant for its leasehold
               interest in the premises as a result of such assignment shall be
               paid to Landlord."

                                       25
<PAGE>

               (f)  Paragraph 12(g) of the Lease is hereby deleted and the
following language is substituted in its place:

               "(g) In the case of a subletting, one-half (1/2) of all sums or
               economic consideration received by Tenant as a result of such
               subletting shall be paid to Landlord after first deducting (i)
               the cost of leasehold improvements made to the sublet portion of
               the premises at Tenant's expense, amortized over the term of this
               Lease except for leasehold improvements made for the specific
               benefit of the sublessee, which shall be amortized over the term
               of the sublease, and (ii) the cost of any real estate commissions
               and other reasonable costs (including attorneys' fees) incurred
               in connection with such subletting, amortized over the term of
               the sublease."

     12.  Amendment of Paragraph 13: Default by Tenant. Paragraph 13(a)(2) of
          ---------------------------------------------
the Lease is hereby deleted and the following language is substituted in its
place:

               "default by Tenant in the performance of any of the other terms,
               covenants, agreements or conditions contained herein and, if the
               default is curable, the continuation of such default for a period
               of ten (10) days after notice by Landlord or beyond the time
               reasonably necessary for cure if the default is of the nature to
               require more than ten (10) days to remedy;

     13.  Amendment of Paragraph 14: Default by Landlord. The following language
          ----------------------------------------------
is hereby added at the end of Paragraph 14 of the Lease:

               "Following any such default by Landlord in its obligations to
               maintain the Building or the premises under this Lease, upon
               prior notice to Landlord, Tenant may perform such obligations and
               Landlord shall reimburse Tenant for Tenant's reasonable out-of-
               pocket costs incurred in connection with such performance."

     14.  Amendment of Paragraph 15:  Security Deposit.
          --------------------------------------------

               (a) The sixth sentence of Paragraph 15 of the Lease is hereby
deleted and the following language is substituted in its place:

               "The Deposit, or so much thereof as has not theretofore been
               applied by Landlord, shall be returned, without payment of
               interest for its use, to Tenant (or, at Landlord's option, to the
               last assignee, if any, of Tenant's interest hereunder) at the
               expiration of the term hereof, and after Tenant has vacated the
               premises."

               (b)  The following language is hereby added at the end of
Paragraph 15 of the Lease

               "The Deposit shall be increased on September 15, 2000 by way of
               Tenant's delivery to Landlord, as security for the faithful
               performance of all of Tenant's obligations under this Lease, of
               an irrevocable stand-by letter of credit (the "Letter of Credit")
                                                              ----------------
               for the account of Tenant and for the benefit of Landlord and any
               successor in interest to Landlord, issued by a National Banking
               Association

                                       26
<PAGE>

               member satisfactory to Landlord, and in such form as shall be
               acceptable to Landlord. The amount of the Letter of Credit shall
               be as follows:

                    (a)  If Tenant's free cash reserves, as reasonably
               determined by Landlord, as of September 1, 2000 are less than
               $25,000,000, the Letter of Credit shall be in an amount equal to
               Seven Hundred Seventy-five Thousand Dollars ($775,000).

                    (b)  If Tenant's free cash reserves, as reasonably
               determined by Landlord, as of September 1, 2000 are equal to or
               greater than $25,000,000 but less than $75,000,000, the Letter of
               Credit shall be in an amount equal to Five Hundred Eighty-one
               Thousand Two Hundred Fifty Dollars ($581,250).

                    (c)  If Tenant's free cash reserves, as reasonably
               determined by Landlord, are greater than $75,000,000, the Letter
               of Credit shall be in an amount equal to One Hundred Ninety-three
               Thousand Seven Hundred Fifty Dollars ($191,750).

                    (d)  If during the term of the Lease Xenogen completes four
               consecutive quarterly periods with positive cash flows, the
               Deposit will be reduced to $46,001 (one month rent @$2.16/sf)
               subject to any other special security deposit requirements
               related to Xenogen's specialized tenant improvements.

               Landlord shall have the right to terminate this Lease on thirty
               (30) days' notice to Tenant if Tenant shall fail to deliver the
               Letter of Credit to Landlord in accordance with this Paragraph 15
               on or before September 15, 2000. Landlord shall be entitled to
               draw upon the Letter of Credit from time to time for any of the
               following reasons: (i) upon or following the occurrence of any
               event of default under this Lease (A) to pay any amounts payable
               by Tenant to Landlord hereunder, and (B) to compensate Landlord
               for any expense, loss or damage incurred or suffered by Landlord
               in connection with the event of default; or (ii) if Tenant fails
               to give Landlord evidence of renewal of the Letter of Credit then
               in effect as provided below; or (iii) upon the expiration or
               earlier termination of the Lease, to pay any amount then due and
               payable by Tenant to Landlord. Landlord shall not draw upon the
               Letter of Credit in an amount in excess of the amount required to
               pay amounts or charges then due and payable by Tenant hereunder,
               or to compensate Landlord for any loss or damage which Landlord
               may suffer as a result of Tenant's default hereunder; provided,
               however, if the amount of any draw made in good faith by Landlord
               on the Letter of Credit exceeds such amounts, the making of such
               excess draw shall not constitute a breach of this Lease or of the
               terms of the Letter of Credit, and the balance of the cash
               proceeds drawn under the Letter of Credit, if any, shall be held
               by Landlord as additional security for the faithful performance
               of all of tenant's obligations under this Lease in accordance
               with this Paragraph 15. Tenant shall maintain the Letter of
               Credit until thirty (30) days after the later of (1) the Lease
               expiration date or (2) vacation of the Premises by Tenant and all
               parties claiming through Tenant. Tenant shall

                                       27
<PAGE>

               renew the Letter of Credit prior to its expiration or arrange for
               issuance of a new Letter of Credit in accordance with the terms
               hereof. If Tenant fails to give Landlord evidence of renewal of
               the Letter of Credit or issuance of anew Letter of Credit at
               least thirty (30) days prior to expiration of the Letter of
               Credit then in effect, Landlord shall be entitled to draw down
               the full amount of the Letter of Credit and the amount so drawn
               shall be treated as a Deposit hereunder. Landlord (and any
               subsequent transferee) may transfer the Letter of Credit to the
               purchaser of Landlord's interest in the Premises and, upon such
               transfer and the assumption by such transferee in writing or
               otherwise by operation of law of Landlord's obligations with
               respect thereto, Landlord shall be discharged from any further
               liability with respect to the Letter of Credit. If the Letter of
               Credit cannot be transferred, Landlord shall notify Tenant, and
               Tenant shall deliver a new Letter of Credit to the purchaser of
               Landlord's interest in the Premises and, if Tenant does not
               provide such new Letter of Credit within thirty (30) days after
               request from Landlord, Landlord may draw upon the full amount of
               the Letter of Credit."

     15.  Amendment of Paragraph 16:  Estoppel Certificate.  The first clause of
          ------------------------------------------------
the first sentence of Paragraph 16(a) of the Lease is hereby deleted and the
following language is substituted in its place:

               "Tenant shall, at any time within twenty (20) days after
               receiving notice from Landlord, execute, acknowledge and deliver
               to Landlord a statement certifying"

     16.  Amendment of Paragraph 17:  Subordination.  The following language is
          -----------------------------------------
hereby added at the end of Paragraph 17 of the Lease:

               "Notwithstanding the foregoing, within ninety (90) days following
               the date of this Lease, Landlord shall cause Teachers Insurance
               and Annuity Association, or its successor, as beneficiary of the
               deed of trust presently encumbering the Building, to execute and
               deliver a counterpart of a Recognition, Non-disturbance and
               Attornment Agreement in the form attached to the Addendum to this
               Lease, with such revisions as Tenant reasonably may request,
               which Agreement shall promptly be executed and delivered by
               Tenant. Tenant shall reimburse Landlord within thirty (30) days
               following Landlord's request for any out-of-pocket costs incurred
               by Landlord in connection with Tenant's negotiation of the form
               of such Recognition, Non-disturbance and Attornment Agreement."

     17.  Amendment of Paragraph 20: Notices. The first clause of Paragraph 20
          ----------------------------------
of the Lease is hereby deleted and the following language is substituted in its
place:

               "All notices, consents, demands and other communications from one
               party to the other given pursuant to the terms of this Lease
               shall be in writing and shall be deemed to have been fully given
               two (2) business days following deposit in the United States
               mail, certified or registered, postage prepaid and addressed as
               follows:"

                                       28
<PAGE>

     18.  Amendment of Paragraph 21:  General Provisions.
          ----------------------------------------------

               (a)  Paragraph 21(e) of the Lease is hereby deleted and the
following language is substituted in its place:

               "If Tenant remains in possession of the premises or any part
               thereof after the expiration of the term with the consent of
               Landlord, such occupancy shall be a tenancy from month to month
               at a rental in the amount of one hundred fifty percent (150%) of
               the last month's rental during the term, plus all other charges
               payable hereunder and upon all of the terms of the Lease."

               (b)  The first sentence of Paragraph 21(g) of the Lease is hereby
deleted and the following language is substituted in its place:

               "Landlord and Landlord's agents shall have the right to enter the
               premises at reasonable times upon at least twenty-four (24)
               hours' prior notice, except in emergencies, for the purpose of
               inspecting the same, showing the same to prospective purchasers,
               tenants, lenders and other interested parties, and making such
               alterations, repairs, improvements or additions to the premises
               or to the Building as Landlord may deem necessary or desirable."

               (c)  The following language is hereby added at the end of
Paragraph 21(k) of the Lease:

               "and liabilities accruing prior to such sale."

               (d)  The following language is hereby added as Paragraph 21(o) of
the Lease:

               "(o) Except as otherwise set forth, whenever this Lease requires
               an approval, consent, designation, determination, selection or
               judgment by either Landlord or Tenant, such approval, consent,
               designation, determination, selection or judgment and any
               conditions imposed thereby shall be reasonable and shall not be
               unreasonably withheld or delayed and, in exercising any right or
               remedy hereunder, each party shall at all times act reasonably
               and in good faith."

     19.  Option to Extend Term:
          ---------------------

               (a)  Tenant shall have one (1) option to extend the term of the
Lease for a five (5) year period (the "Option Period") with the Option Period
                                       -------------
commencing upon the expiration of the initial term of the Lease; provided,
however, such option shall be subject to the following conditions:

                         (i)  At the time the option is exercised, this Lease
shall be in full force and effect and Tenant shall not be in default hereunder,
and

                         (ii) The option must be exercised by notice given to
Landlord not earlier than twelve (12) months and not later than nine (9) months
prior to the then-scheduled expiration of the term of this Lease.

                                       29
<PAGE>

               (b)  In the event the option is timely and effectively exercised,
the term shall be extended for five (5) additional years, upon all of the terms
and conditions of the Lease; provided, however, that the Base Rent shall be the
then fair market rental value of the Premises, but in no event less than the
monthly rent for February, 2006.

                         (i)  For the purposes hereof, the fair market rental
value of the Premises shall be the monthly rental rate per square foot of
rentable area then prevailing for comparable improved space (without taking into
account the value of improvements made by Tenant at its cost) in the Project,
multiplied by the rentable area of the Premises. If Tenant in good faith
disputes Landlord's determination of fair market rental value, Tenant shall so
notify Landlord and the parties shall negotiate in good faith to resolve the
dispute. If such dispute is not resolved by negotiation between the parties
within thirty (30) days, then fair market rental value shall be determined by
appraisal. Tenant shall pay Base Rent when due based upon Landlord's
determination of fair market rental value, subject to retroactive adjustment
between the parties if the determination by appraisal is different from
Landlord's determination.

                         (ii) When fair market rental value is to be determined
by appraisal, within ten (10) days after the expiration of the 30-day
negotiation period, Landlord and Tenant shall each appoint as an appraiser, a
real estate appraiser with at least ten (10) years of experience in appraising
commercial real property in Alameda County, and give notice of such appointment
to the other. If either Landlord or Tenant shall fail to appoint an appraiser
within ten (10) days after receiving notice of the identity of the other party's
appointed appraiser, then the single appraiser appointed shall be the sole
appraiser and determine the fair market rental value of the Premises. In the
event each party appoints an appraiser, such appraisers shall, within thirty
(30) days after the appointment of the last of them to be appointed, complete
their determinations of fair market rental value and furnish the same to
Landlord and Tenant. If the low appraisal varies from the higher appraisal by
five percent (5%) or less, the fair market rental value shall be the average of
the two valuations. If the low appraisal varies from the high appraisal by more
than five percent (5%), the two appraisers shall, within ten (10) days after
submission of the last appraisal report, appoint a third appraiser who shall
meet the qualifications set forth in this paragraph. If the two appraisers shall
be unable to agree on the selection of a third appraiser in a timely manner then
either Landlord or Tenant may request such appointment by the presiding judge of
the Superior Court of Alameda County. The third appraiser, however selected,
shall be a person who has not previously acted in any capacity for or against
either party. Such third appraiser shall, within thirty (30) days after
appointment, make a determination of fair market rental value and submit an
appraisal report to Landlord and Tenant. The fair market rental value of the
Premises shall be as determined by the third appraiser, unless it is less than
the valuation set forth in the lower appraisal previously obtained, in which
case the valuation set forth in the lower prior appraisal shall be controlling,
or unless it is greater than the valuation set forth in the higher appraisal
previously obtained, in which case the valuation set forth in the higher prior
appraisal shall be controlling. All fees and costs incurred in connection with
the determination of fair market rental value by appraisal shall be paid one-
half by Landlord and one-half by Tenant. Prior to the commencement of the option
period, Tenant and Landlord shall execute an amendment to this Lease setting
forth the option period and revised Base Rent.

                                       30
<PAGE>

     20.  Right of First Offer. Tenant shall have a right of first offer to
          --------------------
lease Suite 102 (the "Offer Space") if it becomes available in the building
                      -----------
commonly identified as 2061 Challenger Drive if and when such space becomes
available. Tenant acknowledges and agrees that the Offer Space is currently
leased to Cell Genesys through April, 2007. Tenant's rights under this paragraph
shall be conditioned upon: (a) 2061 Challenger Drive continuing to be owned by
the same entity which is the Landlord under this Lease: (b) the absence of any
prior rights in favor of the present and any future tenants in 2061 Challenger
Drive, as such rights may exist or be granted in the future; and (c) Tenant not
being in default under this Lease. Subject to the foregoing, if and when the
Offer Space does become available, Landlord shall give notice to Tenant of the
availability of the Offer Space and the terms on which Landlord would be willing
to enter into a lease for such space with Tenant. In no event shall the Base
Rent per square foot payable with respect to the Offer Space be less than the
Base Rent per square foot payable with respect to the Premises at the time the
Offer Space becomes available. If Tenant, by notice to Landlord given within
five (5) business days following the giving of Landlord's notice, so elects, the
parties shall thereafter negotiate in good faith for ten (10) business days with
respect to the potential of leasing the Offer Space to Tenant. If by the end of
such 10-day period, Landlord and Tenant have not entered into a binding
agreement with respect to the lease of the Offer Space to Tenant, or if Tenant
initially does not give Landlord notice of its desire to enter into such
negotiations within the five-day business period set forth above, Landlord shall
thereafter be free to deal with the Offer Space without further reference to
Tenant, unless and until one (1) year or more thereafter the Offer Space again
becomes available.

     21.  Specialized Improvements.  Subject to the provisions of Paragraph 8(c)
          ------------------------
of the Lease and Landlord's election to require a separate, additional security
deposit hereunder, Tenant may install improvements in the Premises that relate
to its permitted uses hereunder, such as lab facilities, that are not ordinary
office use improvements (collectively, "Specialized Improvements").  Tenant
                                        ------------------------
shall have the right to remove the Specialized Improvements, at Tenant's sole
expense, at the expiration or termination of the Lease provided that Tenant
fully restores the Premises to their building standard, open configuration
condition, as existed prior to the installation of such Specialized
Improvements, including, without limitation, removing or capping utility supply
lines and waste return lines as directed by Landlord.  Landlord shall have the
option to require that Tenant deposit a separate, additional security deposit in
connection with the installation of any Specialized Improvements.  In
determining whether to exercise such option, Landlord shall consider the nature
of the Specialized Improvements, the amount of the Deposit then held pursuant to
Paragraph 15, and Tenant's financial condition at the time of Tenant's request
to install Specialized Improvements.  Any separate, additional security deposit
required by Landlord with respect to the Specialized Improvements shall be held
by Landlord as security for the performance of Tenant's obligations hereunder
with respect to removal of the Specialized Improvements and restoration of the
Premises, but shall otherwise be subject to the terms of Paragraph 15 of the
Lease.

                                       31
<PAGE>

     IN WITNESS WHEREOF, Landlord and Tenant have executed this Addendum as of
the date of the Lease.

TENANT:                         LANDLORD:

XENOGEN CORPORATION,            ALAMEDA REAL ESTATE INVESTMENTS,
a California corporation        a California limited partnership

                                By:  Vintage Alameda Investments, LP
By: /s/ Pamela Reilly Contag         a California limited partnership
   --------------------------        operating general partner
Name:   Pamela Reilly Contag
     ------------------------        By:  Vintage Properties-Alameda Commercial,
Title:  CEO and President                 a California corporation,
      -----------------------             managing general partner

By:
   --------------------------             By: /s/ Joseph R. Seiger
Name:                                        --------------------------------
     ------------------------             Name:   Joseph R. Seiger
Title:
      -----------------------             Title: President

                                       32

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