Document:

<PAGE>

                                                                   EXHIBIT 10.54

                           BAYSHORE CORPORATE CENTER
                                 OFFICE LEASE

                                    BETWEEN

                       ________________________________

                         CORNERSTONE PROPERTIES I, LLC

                                      AND

                                 AVANTGO, INC.

                       ________________________________

                                       1.
<PAGE>

                         CORNERSTONE PROPERTIES I, LLC
                         -----------------------------
                                LEASE "SUMMARY"
                                --------------

Lessor:                            CORNERSTONE PROPERTIES I, LLC A California
                                   Limited Liability Company Bayshore Corporate
                                   Center 1720 S. Amphlett Boulevard, Suite 110
                                   San Mateo, CA 94402
                                   650-574-2104

Lessee Name:                       AVANTGO, INC.
Premises Building/Suite:           1700 South Amhplett Blvd., Suite 200
                                   San Mateo, Ca 94402

Tenant Phone Number:               650/638-3399
Tenant Fax Number:                 650/638-3398

Tenant Contact:                    Felix Lin

Alternate Tenant Contact:          none

Billing Name and Address:          1700 South Amphlett Blvd., Suite 300
                                   San Mateo, CA 94402

Personal Guarantor(s):             none

Use:                               Software research and development

Rentable Area of Premises:         3505 RSF

Original Lease
Commencement Date:                 August 1, 1999

Lease Commencement Date:           August 1, 1999

Lease Expiration:                  March 31, 2002

Lease Term:                        Two Years and 7 months

Rent Schedule:
August 1, 1999 - July 31, 2000     $2.85/square foot     $ 9,989.00/month
August 1, 2000 - July 3l, 2001     $2.95/square foot     $10,340.00/month
August l, 2001 - March 31, 2002    $3.05/square foot     $10,690.00/month

Security Deposit:                  $10,690.00

$10,690.00 FOR THE SECURITY DEPOSIT WILL BE DUE UPON EXECUTION OF
THIS LEASE.

Tenant Improvements:
Costs paid by Lessor: n/a
Costs paid by Lessee: Any Requested Tenant Improvements

Tenant's Common Area
Expense Share and Base Year:       1.09%(332,000) 1999 BASE YEAR

Tenant's Minimum General
Liability Insurance:               $1,000,000.00 per occurrence
                                   $  500,000.00 per person, per occurrence
                                   $  100,000.00 property damage

<PAGE>

Additional Bldg/Suite
Tenant Occupies:                   none

Each reference in the Lease to the "Summary" shall mean the respective
information set forth above and shall be deemed to incorporate all of the terms
provided under the particular Lease paragraph pertaining to such information. To
the extent there is any conflict between the provisions hereof and any more
specific provision of this Lease, such more specific provision shall control.
<PAGE>

                             OFFICE BUILDING LEASE
                             ---------------------
                               TABLE OF CONTENTS
                               -----------------
<TABLE>
<CAPTION>
Article                                                           Page
---------                                                         ----
<S>                                                               <C>
 1.  PREMISES                                                       3
 2.  TERM                                                           3
 3.  RENT; ADDITIONAL CHARGES                                       3
 4.  ADDITIONAL CHARGES FOR EXPENSES AND REAL ESTATE TAXES          4
 5.  USE                                                            4
 6.  CONSTRUCTION OF PREMISES; BUILDING CHANGES                     5
 7.  ALTERATIONS                                                    5
 8.  REPAIRS AND MAINTENANCE                                        6
 9.  LIENS                                                          6
10.  COMPLIANCE WITH LAWS AND INSURANCE REQUIREMENTS                6
11.  PROTECTION OF LENDERS                                          7
12.  DAMAGE AND DESTRUCTION                                         7
13.  EMINENT DOMAIN                                                 9
14.  ASSIGNMENT AND SUBLETTING                                      9
15.  UTILITIES AND SERVICES                                        10
16.  DEFAULT                                                       10
17.  LIABILITY OF LANDLORD; INDEMNITY BY TENANT                    12
18.  INSURANCE                                                     13
19.  ACCESS TO PREMISES                                            14
20.  NOTICES                                                       14
21.  TENANT'S CERTIFICATE                                          15
22.  TAX ON TENANT'S PERSONAL PROPERTY                             15
23.  SECURITY DEPOSIT                                              15
24.  LANDLORD'S OPTION TO RELOCATE TENANT                          15
25.  GUARANTOR                                                     16
26.  SURRENDER OF LEASE PREMISES                                   16
27.  MISCELLANEOUS                                                 17

28.  SIGNATURE PAGE                                                19
</TABLE>

Exhibits:
--------

A    FLOOR PLAN(S)                                                 20
B    DEFINITIONS OF REAL ESTATE TAXES, BUILDING EXPENSES           21
     AND COMMON AREA EXPENSES
C    RULES AND REGULATIONS                                         23
D    PHONE AGREEMENT                                               26
E    COMMENCEMENT MEMORANDUM                                       27

                                      2.
<PAGE>

                                 OFFICE LEASE
                                 ------------

     THIS LEASE is entered into as of August 2, 1999, by and between CORNERSTONE
PROPERTIES I, LLC, a California Limited Liability Company ("Landlord"), and
AVANTGO, INC.("Tenant").

     Landlord and Tenant hereby agree as follows:

     1.   PREMISES
          --------

          Subject to the contents of this Lease, Landlord hereby leases to
Tenant and Tenant hereby leases from Landlord the premises described in the
Basic Lease Information Summary (the "Summary") (the "Premises") in the building
described in the Summary (the "Building"), as shown on the floor plan (s)
attached as Exhibit A to this Lease. The Building is part of an office complex
consisting of 1650-1730 S. Amphlett Blvd. (the "Complex"). All measurements of
area contained in this Lease are conclusively agreed to be correct and binding
upon the parties, even if a subsequent measurement of any one of these areas
determines that it is more or less than the amount of area reflected in the
Lease. Any such subsequent determination that the area is more or less than
shown in this Lease shall not result in a change in any of the computations of
rent, improvement allowances or other matters described in this Lease where area
is a factor.

     2.   TERM
          ----

          The term of this lease (the "Term") commences on the earlier of (a)
the Target Commencement Date; or (b) the date on which Tenant first occupies all
or any portion of the Premises. The dates on which the Term commences and
terminates pursuant to this Article 2 are herein called the "Commencement Date
and the "Expiration Date," respectively. If, for any reason, Landlord cannot
deliver possession of the Premises to Tenant on or prior to the Commencement
Date, this Lease shall not be void or voidable nor shall Landlord be liable to
Tenant for any loss or damage resulting therefrom. In such case, Tenant shall
not pay any rent and the Commencement Date shall not occur until such date as
Landlord can deliver the Premises, provided, however that if Landlord's failure
to deliver the Premises is attributable to any action or inaction by Tenant,
then the Commencement Date shall not be advanced to the date on which possession
of the Premises is delivered to Tenant and Landlord shall be entitled to full
performance by Tenant (including payment of rent) from the date the Premises
would have been ready for delivery to Tenant but for Tenant's action or
inaction.

     3.   RENT, ADDITIONAL CHARGES
          ------------------------

          3.1 Base Rent. Tenant will pay to Landlord during the Term the monthly
Base Rent set forth in the Summary (the "Base Rent") in consecutive monthly
installments on or before the first day of each calendar month, in advance, at
the address specified for Landlord in the Summary, or such other place as
Landlord may designate in writing, without any prior demand and without any
deductions or setoff. Upon execution of this Lease, Tenant shall pay to Landlord
the first month's Base Rent. If the Commencement Date occurs on a day other than
the first day of a calendar month, or the Expiration Date occurs on a day other
than the last day of a calendar month, then the rental for such fractional month
will be prorated based on a thirty (30) day month.

          3.2 Additional Charges. Tenant shall pay to Landlord all charges and
other amounts required to be paid by Tenant under this Lease (herein called
"Additional Charges") as additional rent at the place where the Base Rent is
payable. Landlord will have the same remedies for a default in the payment of
any Additional Charges as for a default in the payment of Base Rent. (Base Rent
and Additional Charges are sometimes collectively referred to herein as "rent.")

          3.3 Late Charge. If Tenant fails to pay any Base Rent or additional
Charges within five (5) days after the date the same is due and payable, such
unpaid amounts will be subject to a late payment

                                      3.
<PAGE>

charge equal to ten percent (10%) of the unpaid mounts in each instance. The
late payment charge has been agreed upon by Landlord and Tenant, after
negotiation, as a reasonable estimate of the additional administrative costs and
detriment that will be incurred by Landlord as a result of any such failure by
Tenant, the actual costs thereof being extremely difficult if not impossible to
determine. The late payment charge constitutes liquidated damages to compensate
Landlord for its damages resulting from such failure to pay and shall be paid to
Landlord together with such unpaid amounts.

     4.   ADDITIONAL CHARGES FOR EXPENSES AND REAL ESTATE TAXES
          -----------------------------------------------------

          4.1 Definition of Expenses. For purposes of this Article 4, the
following terms shall have the meanings set forth in this Section 4.1. "Tenant's
Building Percentage Share", Tenant's Common Area Expense percentage Share" and
"Base Year" shall be as set forth in the Summary. Landlord may adjust these
percentages as a result of any change in the rentable area of the Premises or
the total rentable area of the Building or the other building in the Complex.
"Computation Year" means each calendar year during the Term, including any
partial calendar year in which the Term may commence or terminate. "Real Estate
Taxes", "Building Expenses", "Insurance Expenses" and "Common Area Expenses" are
defined in Exhibit B to this Lease.
           ---------

          4.2 Payment of Charges. From the first day of the thirteenth month of
the Term through the Expiration Date, Tenant shall pay to Landlord as Additional
Charges (i) Tenant's Building Share of the total dollar increase, if any, in
Building Expenses attributable to each Computation Year over Building Expenses
for the Base Year, (ii) Tenant's Building Share of the total dollar increase, if
any, in Real Estate Taxes attributable to each Computation Year over Real Estate
Taxes for the Base Year, (iii) Tenant's Building Share of the total dollar
increase, if any, in Insurance Expenses attributable to each Computation Year
over Insurance Expenses for the Base Year and (iv) Tenant's Common Area Expense
Share of the total dollar increase, if any, in Common Area Expenses attributable
to each Computation Year over Common Area Expenses for the Base Year. During the
last month of each Computation Year or as soon thereafter as practicable,
Landlord shall give to Tenant notice of Landlord's estimate of the amounts
payable by Tenant for the following Computation Year. On or before the first day
of each month during the following Computation Year, Tenant shall pay to
Landlord one-twelfth (l/12th) of the estimated amounts, provided that until
Landlord gives such notice, Tenant shall continue to pay on the basis of the
prior year's estimate until the first day of the calendar month after Landlord
gives such notice. If at any time or times Landlord determines that the amounts
payable by Tenant for the current Computation Year will vary from its estimate
given to Tenant, Landlord, by notice to Tenant, may revise its estimate for the
Computation Year, and subsequent payments for the Computation year shall be
based upon the revised estimate. Following the end of each Computation Year,
Landlord shall deliver to Tenant a statement of amounts payable for the
Computation Year. If the statement shows an amount owing by Tenant that is less
than the payments for such Computation Year previously made by Tenant, and if no
Event of Default is outstanding, Landlord shall credit the amount to the next
payments of rent due. If the statement shows an amount owing by Tenant that is
more than the estimated payments for the Computation Year previously made by
Tenant, Tenant shall pay the deficiency to Landlord within thirty (30) days
after delivery of such statement. The respective obligations of Landlord and
Tenant under this Section 4.2 shall survive the Expiration Date. If the
Commencement Date is a day other than the first day of a Computation Year or the
Expiration Date is a day other than the last day of a Computation Year, the
adjustment in rent pursuant to this Section 4.2 for such Computation Year shall
be prorated based on a 365-day year.

     5.   USE
          ---

          5.1 Limitations. Tenant shall use and continuously occupy the Premises
solely for the use or uses specified in the Summary and for no other use or
purpose. Tenant shall take no action, nor permit any action to be taken, in or
about the Premises that will in any way increase the existing rate of or affect
any fire or other insurance upon the Building or any of its contents, or cause
cancellation of any insurance policy covering all or any part of the Building or
any of its contents, or which will in any way injure or interfere with the
rights of other tenants or occupants of the Building, nor shall Tenant use or
allow the Premises to be used for unlawful or objectionable purpose, nor cause,
maintain or permit any nuisance in, on or about the Premises, nor commit nor
suffer to be committed any waste in, on or upon the Premises. Tenant shall not
use or operate any equipment, machinery or apparatus within the Premises which
will injure, vibrate or shake the Premises or the Building, overload existing
electrical systems or other utilities or equipment servicing the Premises or
Building, or impair the efficient operation of the sprinkler system (if

                                      4.
<PAGE>

any) or the heating, ventilating and air conditioning equipment within or
servicing the Premises or the Building. Tenant shall not cause or permit any
Hazardous Materials to be brought upon, stored, used, generated or released or
disposed of on, under, from or about the Premises, Building or Complex
(including, without limitation, the soil and groundwater thereunder) without the
prior written consent of Landlord. As used herein, the term "Hazardous
Material," means any hazardous or toxic substance, material or waste which is or
becomes regulated by any local governmental authority, the State of California
or the United States Government. The term "Hazardous Material," includes,
without limitation, petroleum products, asbestos, PCB's, and any material or
substance which is (i) defined as hazardous or extremely hazardous pursuant to
Section 66160 of Title 26 of the California Code of Regulations, Division 22,
(ii) defined as a "hazardous waste" pursuant to Section 1004 of the Federal
Resource Conservation and Recovery Act, 42 U.S.C., Section 6901 et seq. (42
U.S.C. Section 6903), or (iii) defined as "hazardous substance" pursuant to
Section 101 of the Comprehensive Enviromental Response, Compensation and
Liability Act, 42 U.A.C., Section 9601 et seq. (42 U.S.C. 6901).

          5.2 Common Area. Tenant shall have a non-exclusive right to use the
Common Area, provided, however, that Tenant's use of the Common Area shall be
subject to such rules and regulations as Landlord shall make from time to time.
As used in this Lease, the term "Common Area" shall mean the area and
improvements designated by Landlord from time to time as "Common Area" for the
use and enjoyment of tenants of the Complex. Landlord reserves the right, from
time to time, to: (i) utilize portions of the Common Area for entertainment,
displays, product shows, the leasing of kiosks or such other uses as, in
Landlord's judgment, tend to attract the public, change the shape, size,
location and extent of improvements on the Common Area; (ii) eliminate or add
any improvements; and (iii) temporarily close any portion of the Common Areas
for repairs, remodeling and/or alteration, to prevent a public dedication or the
accrual of prescriptive rights, or for any other reason deemed sufficient by
Landlord.

     6.   CONSTRUCTION OF PREMISES; BUILDING CHANGES
          ------------------------------------------

          Landlord shall construct the Premises and perform the work and make
the installations in the Premises substantially as set forth in Exhibit "A" to
                                                                -----------
this Lease (the "floor plan"). Landlord reserves the right, at any time and from
time to time, to make alterations, additions, repairs or improvements to or in
or to decrease the size or area of all or any part of the Building, the fixtures
and equipment therein and the areas outside the' Building, and the Common Area,
and to change the arrangement and/or location of entrances or passageways,
doors, corridors, elevators, stairs, toilets and other public parts of the
Building, provided that any such alterations or additions shall not materially
diminish the quality or quantity of services being provided to the Premises or
adversely affect the functional utilization of the Premises.

     7.   ALTERATIONS
          -----------

          7.1 Tenant's Trade Fixtures. During the Term of this Lease, Tenant may
install Tenant's trade fixtures which may be removed without material injury to
the Premises on the Premises without the prior consent of Landlord. All Tenant's
trade fixtures shall remain Tenant's property. Tenant's trade fixtures shall not
include the initial Tenant Improvements paid for with the funds of Landlord nor
any improvements thereafter made to the Premises by Landlord at any time with
Landlord's Funds.

          7.2 Consent Requirement for Alterations. Tenant shall make no
alterations, additions or improvements (collectively, "Alterations")  to the
                                                       -----------
Premises or any part thereof without obtaining the prior written consent of
Landlord. Such consent may be granted or withheld in Landlord's sole and
absolute discretion. Landlord may impose as a condition to such consent such
requirements as Landlord may deem necessary, in its sole and absolute discretion
including, without limitation: (i) that Landlord be furnished with working
drawings before work commences; (ii) that performance and labor and material
payment bonds be furnished; (iii) that Landlord approve the contractor by whom
the work is to be performed; (iv) that adequate course of construction insurance
be in place and the Landlord is named as an additional insured under the
contractor's liability and property damage policies; and (v) that Landlord's
instructions relating to the manner in which the work is to be done and the
times during which it is to be accomplished be complied with. All such
alterations, additions or improvements must be done in compliance with all
applicable laws, in a good and workmanlike manner and diligently prosecuted to
completion. Tenant shall deliver to Landlord upon commencement of such work, a
copy of the building permit with respect thereto. All such work shall be
performed so as not to obstruct the access to the Premises of any other tenant
in the

                                      5.
<PAGE>

Building or Complex. Should Tenant make any alterations without Landlord's prior
written consent, Landlord shall have the right, in addition to and without
limitation of any right or remedy Landlord may have under this Lease, at law or
in equity, to require the Tenant to remove all or some of the alterations at
Tenant's sole cost and restore the Premises to the same condition as existed
prior to undertaking the alterations. Tenant shall notify Landlord in writing at
least ten (10) days prior to the commencement of any such work in or about the
Premises and Landlord shall have the right at any time and from time to time to
post and maintain notices of non-responsibility in or about the Premises.

          7.3 Possession. All Tenant's Alterations shall remain the property of
Tenant during the Term but shall not be altered or removed from the Premises. At
the expiration or sooner termination of the Term, all Tenant's Alterations shall
be surrendered to Landlord and shall then become Landlord's property, and
Landlord shall have no obligation to reimburse Tenant for all or any portion of
the value or cost thereof; provided, however, that if Landlord requires Tenant
to remove any Tenant's Alterations, Tenant shall so remove such Tenant's
Alterations, and Tenant shall restore the Premises to the condition which
existed prior to the installation of such Tenant's Alterations, prior to the
expiration or sooner termination of the Term.

     8.   REPAIRS AND MAINTENANCE
          -----------------------

          8.1 Tenant's Obligations. By occupying the Premises, Tenant accepts
the Premises as being in the condition in which Landlord is obligated to deliver
the Premises under the terms of this Lease. Tenant shall, at all times during
the Term, and at Tenant's sole expense, keep and maintain all of the Premises in
good order, condition and repair, including replacement where necessary. Tenant
shall at all times during the Term, and at Tenant's sole expense, keep and
maintain the Premises and every part thereof in good order, condition and
repair. Tenant's obligation shall include, without limitations, the following:
all plumbing and sewage facilities within the Premises (including, without
limitations, sinks, facuets, toilets and drains) and all ducts, pipes, vents,
and other parts of the HVAC or plumbing systems within the Premsises; all
fixtures, interior walls, floors, carpets and ceilings within the Premises; all
electrical facilities and equipment within the Premises (including, without
limitations, all lighting fixtures, lamps, bulbs, tubes, fans, vents, exhaust
equipment and systems, wires and conduits); and all gas facilities and
equipment within the Premises (including, without limitations, all conduits and
pipes. Tenant shall at the end of the Term surrender the Premises to Landlord in
the same condition as when received, except for ordinary wear and tear and
Alterations. Landlord has no obligation and has made no promise to alter,
remodel, improve, repair, decorate or paint all or any part of the Premises, the
Building or the Common Area except as specifically set forth in the Lease.

          8.2 Landlord's Obligations. Landlord shall repair and maintain the
structural portions of the Building, the Building Systems and the Common Area.
If the necessity for such maintenance and repairs is in any way caused by the
act, neglect, fault, or omission of Tenant, its agents, servants, employees or
invitees, Tenant shall pay promptly to Landlord the reasonable cost of such
maintenance and repairs. Landlord shall not be liable for any failure to make
any such repairs or to perform any such maintenance unless Landlord receives
notice of the need for such repairs or maintenance from Tenant and fails to make
such repairs or perform such maintenance for a reasonable period of time
following such notice by Tenant. Rent shall not abate nor shall Landlord be
liable as a result of any injury to or interference with Tenant's business
arising from the making of any repairs, or the performance of any maintenance,
in or to any portion of the Building, the Premises or the Common Area, excepting
the negligence or willful misconduct of Landlord, Agents, servants, employees,
licensees or contractors.

"As used herein, the term "Building Systems" shall mean all systems and
equipment (including, without limitations, plumbing, HVAC, electrical,
fire/life safety, elevator, and security systems) that serve ther entire
Building or portions of the Building other than simply the respective premises
of the tenants of the Building."

          8.3 Tenant's Failure to Repair. If Tenant refuses or neglects to
repair and maintain the Premises as required hereunder to the reasonable
satisfaction of Landlord, Landlord at any time following ten (10) days from the
date on which Landlord shall make a written demand on Tenant to effect such
repair and/or maintanance, may enter upon

                                      6.
<PAGE>

     9.   LIENS
          -----

          Tenant shall keep the Premises and the Building free from any liens
arising out of any work performed, material furnished or obligations incurred by
or for Tenant. In the event that Tenant shall not, within ten (10) days
following the imposition of any such lien, cause the lien to be released of
record by payment or posting of a proper bond, Landlord shall have in addition
to all other remedies provided herein and by law the right but not the
obligation to cause same to be released by such means as it shall deem proper,
including payment of the claim giving rise to such lien. All such sums paid by
Landlord and all expenses incurred by it in connection therewith (including
without limitation reasonable counsel fees) shall be payable to Landlord by
Tenant upon demand. Landlord shall have the right at all times to post and keep
posted on the Premises any notices permitted or required by law or that Landlord
shall deem proper for the protection of Landlord, the Premises, and the
Building, from mechanics' and material men's liens. Tenant shall give to
Landlord at least five (5) business days' prior written notice of commencement
of any repair or construction on the Premises.

     10.  COMPLIANCE WITH LAWS AND INSURANCE REQUIREMENTS
          -----------------------------------------------

          Tenant, at Tenant's cost and expense, and irrespective of the cost of
compliance, shall comply with all laws, orders and regulations of federal,
state, county and municipal authorities relating to the Premises or the use or
occupancy thereof, and with all rules, orders, regulations or requirements of
the American Insurance Association (formerly the National Board of Fire
Underwriters) and with any similar body that shall hereafter perform the
function of such Association, except that Tenant shall not be required to make
any structural Alterations in order to comply unless such Alterations shall be
necessitated by Tenant's Alterations or Trade Fixtures, by Tenant's particular
use of the Premises, by Tenant's application for any permit or governmental
approval, and/or by the acts, omissions or negligence of Tenant or its servants,
employees, contractors, agents, visitors or licensees.

     11.  PROTECTION OF LENDERS
          ---------------------

          11.1 Subordination. Without the necessity of any additional document,
this Lease shall be the subject and subordinate at all times to: (a) all
reciprocal easement agreements and all ground leases or underlying leases which
may now exist or hereafter be executed affecting the Building, the land on which
the Building is located or the Common Area, or any of the foregoing, and (b) the
lien of any mortgage or deed of trust which may now exist or hereafter be
executed in any amount for which the Building, land on which the Building is
located, ground leases or underlying leases, or Landlord's interest or estate in
any of said items, is specified as security. Notwithstanding the foregoing,
Landlord shall have the right to subordinate or cause to be subordinated to this
Lease any of the items referred to in clause (a) or (b) above. Tenant shall
execute and deliver, upon demand by Landlord and in the form requested by
Landlord, any additional documents evidencing the priority or subordination of
this Lease with respect to any such ground leases, underlying leases, reciprocal
easement agreements or similar documents or instruments, or with respect to the
lien of any such mortgage or deed of trust and containing such matters as
lenders customarily and reasonably require in connection with such agreements,
including, provisions that the lender will not be liable for: (i) the return of
any security deposit unless the lender receives it from Landlord and (ii) any
defaults on the part of Landlord occurring prior to the time lender takes
possession. Tenant's failure to execute any such document within ten (10) days
after written demand therefor shall constitute an event of Tenant's default by
Tenant under this Lease.

          11.2 Attornment. If Landlord's interest in the Property is acquired by
any ground Landlord, beneficiary under a deed of trust, mortgagee, or purchaser
at a foreclosure sale, Tenant shall attorn to the transferee of or successor to
Landlord's interest in the Property and recognize such transferee or successor
as Landlord under this Lease. Tenant waives the protection of any statute or
rule of law which gives or purports to give Tenant any right to terminate this
Lease or surrender possession of the Property upon the transfer of Landlord's
interests.

     12.  DAMAGE AND DESTRUCTION
          ----------------------

          12.1 Definition of Terms. For the purposes of this Lease, the term:
(a) "Insured Casualty" means damage to or destruction of the Premises from a
cause actually insured against, for which the

                                      7.
<PAGE>

insurance proceeds paid or made available to Landlord are sufficient to rebuild
or restore the Premises under then-existing building codes to the condition
existing immediately prior to the damage or destruction; and (b) "Uninsured
Casualty" means damage to or destruction of the Premises from a cause not
actually insured against, or from a cause actually insured against but for which
the insurance proceeds paid or made available to Landlord are for any reason
insufficient to rebuild or restore the Premises under then-existing building
codes to the condition existing immediately prior to the damage or destruction,
or from a cause actually insured against but for which the insurance proceeds
are not paid or made available to Landlord within twelve (12) months of the
event of damage or destruction.

     12.2 Insured Casualty.

          (a) In the event of an Insured Casualty where the extent of damage or
destruction is less than twenty-five percent (25%) of the then full replacement
cost of the Premises or the Building, Landlord shall rebuild or restore the
Premises or the Building substantially to the condition existing immediately
prior to the damage or destruction, provided that there exist no governmental
codes or regulations that would interfere with Landlord's ability to so rebuild
or restore.

          (b) In the event of an Insured Casualty where the extent of damage or
destruction is equal to or greater than twenty-five percent (25%) of the then
full replacement cost of the Premises or the Building, Landlord may rebuild or
restore the Premises or the Building substantially to the condition existing
immediately prior to the damage or destruction, or terminate this Lease.
Landlord shall notify Tenant in writing within thirty (30) days from the event
of damage or destruction of Landlord's election to either rebuild or restore the
Premises or terminate this Lease.

     12.3 Uninsured Casualty. In the event of an Uninsured Casualty, Landlord
may (i) rebuild or restore the Premises as soon as reasonably possible at
Landlord's expense (unless the damage or destruction was caused by a negligent
or willful act of Tenant, in which event Tenant shall pay all costs of
rebuilding or restoring), in which event this Lease shall continue in full force
and effect or (ii) terminate this Lease, in which event Landlord shall give
written notice to Tenant within thirty (30) days after the event of damage or
destruction of Landlord's election to terminate this Lease as of the date of the
event of damage or destruction, and if the damage or destruction was caused by a
negligent or willful act of Tenant, Tenant shall be liable therefor to Landlord.
Notwithstanding the foregoing, Landlord shall have no right to terminate this
Lease with respect to an Uninsured Casualty if the cost of rebuilding or
restoring the damage caused thereby is equal to or less than Two Hundred Fifty
Thousand Dollars ($250,000).

     12.4 Tenant's Election. Notwithstanding anything to the contrary contained
in this Article 12, Tenant may elect to terminate this Lease in the event the
Premises are damaged or destroyed and, in the reasonable opinion of Landlord's
architect or construction consultants, the restoration of the Premises cannot be
substantially completed within one hundred eighty (180) days after the event of
damage or destruction. Tenant's election shall be made by written notice to
Landlord within ten (10) days after Tenant receives from Landlord the estimate
of the time needed to complete repair or restoration of the Premises. If Tenant
does not deliver said notice within said ten (10) day period, Tenant may not
later terminate this Lease even if substantial completion of the rebuilding or
restoration occurs subsequent to said one hundred eighty (180) day period,
provided that Landlord is proceeding with diligence to rebuild or restore the
Premises. If Tenant delivers said notice within said ten (10) day period, this
Lease shall terminate as of the date of the event of damage or destruction.

     12.5 Continuance of Lease. If Landlord is required or elects to rebuild or
restore the Premises pursuant to this Article 12, this Lease shall remain in
effect and Tenant shall have no claim against Landlord for compensation for
inconvenience or loss business during any period of repair or restoration.

     12.6 Damage or Destruction Near End of Lease Term. Notwithstanding anything
to the contrary contained in this Article 12, in the event the Premises are
damaged or destroyed in whole in part (regardless of the extent of damage) from
any cause during the last twelve (12) months of the Lease Term, Landlord may, at
Landlord's option, terminate this Lease as of the date of the event of damage or
destruction by giving written notice to Tenant of Landlord's election to do so
within thirty (30) days after the event of such damage or destruction. For
purposes of this Section 12.6, if Tenant has been granted an option to extend or
renew the Lease Term pursuant to another provision of this Lease, then the
damage or destruction shall be deemed to have occurred during the last twelve
(12) months of the Lease Term if

                                      8.
<PAGE>

Tenant fails to exercise its option to extend or renew within twenty (20) days
of the event of damage or destruction.

          12.7  Termination of Lease. If the Lease is terminated pursuant to
this Article 12, the current Rentals shall be proportionately reduced during the
period following the event of damage or destruction until the date on which
Tenant surrenders the Premises, based upon the extent to which the damage or
destruction interferes with Tenant's business conducted in the Premises, as
reasonably determined by Landlord, to the extent such loss is covered as an
insured peril by the insurance carried by Landlord, and to the extent the
resulting loss of income is covered by rental income or other insurance carried
by Landlord.

          12.8  Abatement of Rentals. If the Premises are to be rebuilt or
restored pursuant to this Article 12, the then current Rentals shall be
proportionately reduced during the period of repair or restoration, based upon
the extent to which the making of repairs interferes with Tenant's business
conducted in the Premises, as reasonably determined by Landlord. In the event
Tenant reasonably disputes Landlord's determination regarding Rentals in Section
12.7 above and/or in the preceding sentence, then Tenant shall, within thirty
(30) days following written notice to Tenant of such determination by Landlord,
have the right to send Landlord written notice objecting to such determination
and requesting that Landlord and Tenant determine by arbitration the extent to
which Rentals should be proportionately reduced during the period described in
Section 12.7 above or the period of repair or restoration, which arbitration
shall be carried out pursuant to the rules and procedures of the American
Arbitration Association. All costs and expenses of any such arbitration shall be
shared equally by Landlord and Tenant. The determination of any such arbitration
shall be binding upon Landlord and Tenant.

          12.9  Liability for Personal Property. In no event shall Landlord have
any liability for, nor shall it be required to repair or restore, any injury or
damage to any improvements, alterations or additions to the Premises made by
Tenant, trade fixtures, equipment, merchandise, furniture, or any other property
installed by Tenant or at the expense of Tenant. If Landlord or Tenant do not
elect to terminate this Lease pursuant to this Article 12, Tenant shall be
obligated to promptly rebuild or restore the same to the condition existing
immediately prior to the damage or destruction.

          12.10 Waiver of Civil Code Remedies. Landlord and Tenant acknowledge
that the rights and obligations of the parties upon damage or destruction of the
Premises are as set forth herein; therefore Tenant hereby expressly waives any
rights to terminate this Lease upon damage or destruction of the Premises,
except as specifically provided by this Lease, including without limitation any
rights pursuant to the provisions of Subdivision 2 of Section 1932 and
Subdivision 4 of Section 1933 of the California Civil Code, as amended from time
to time, and the provisions of any similar law hereinafter enacted, which
provisions relate to the termination of the hiring of a thing upon its
substantial damage or destruction.

     13.  EMINENT DOMAIN
          --------------

          If all or any part of the Premises shall be taken as a result of the
exercise of the power of eminent domain or any transfer in lieu thereof, 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 written notice to the
other within thirty (30) days after such date; provided, however, a condition to
Tenant's right to terminate shall be that Tenant's use of the balance of the
Premises is substantially handicapped, impeded or impaired by the taking. If any
material part of the building shall be taken, Landlord shall have the right to
terminate this Lease by written notice to Tenant within thirty (30) days of the
date of taking. 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 the Landlord for the value of any unexpired term of this
Lease or otherwise; provided, Landlord shall have no claim to any portion of the
award that is specifically allocable to Tenant's relocation expenses or the
interruption of or damage to Tenant's business. In the event of a partial taking
of the Premises which does not result in a termination of this Lease, the Base
Rent and Additional Charges thereafter to be paid shall be equitably reduced.

                                      9.
<PAGE>

     14.  ASSIGNMENT AND SUBLETTING
          -------------------------

          14.1 In General. Tenant shall not directly or indirectly, voluntarily
or by operation of law, sell, assign, encumber, pledge or otherwise transfer or
hypothecate its interest in or rights with respect to the Premises or Tenant's
leasehold estate hereunder (collectively, "Assignment"), or permit all or any
portion of the Premises to be occupied by anyone by other than Tenant or sublet
all or any portion of the Premises or transfer a portion of its interest in or
rights with respect to Tenant's leasehold estate hereunder (collectively,
"Sublease") without Landlord's prior consent in each instance.

          14.2 Notice to Landlord. If Tenant desires at any time to enter in an
Assignment or a Sublease, Tenant shall first give notice to Landlord of its
desire to do so, which notice shall contain (a) the name and address of the
proposed assignee or subtenant, (b) the nature of the proposed assignee's or
subtenant's business to be carried on in the Premises, (c) the terms and
provisions of the proposed Assignment or Sublease. In addition thereto, Tenant
shall furnish to Landlord such financial information as Landlord may reasonably
request concerning the proposed assignee or subtenant.

          14.3 Landlord's Option. At any time within fifteen (15) days after
Landlord's receipt of the notice specified in Section 14.2, Landlord may by
notice to Tenant elect to (a) terminate this Lease as to the portion (including
all) of the Premises that is specified in Tenant's notice, with a proportionate
abatement in the Base Rent, (b) consent to the Sublease or Assignment, or (c)
disapprove the Sublease or Assignment; provided, however, if the Landlord elects
not to exercise the option described in (a) above, Landlord shall not
unreasonably withhold its consent to the Assignment or Sublease. Tenant shall
pay as additional rent, Landlord's reasonable attorneys' fees incurred in
connection with the review of any proposed Assignment or Sublease. Tenant agrees
to pay Landlord the amount by which all sums payable to Tenant in connection
with such Assignment or Sublease exceed the total of(a) Base Rent payable by
Tenant to Landlord hereunder, (b) reasonable leasing commission incurred by
Tenant in connection therewith, and (c) the cost of any Alterations reasonably
incurred in connection therewith. If Landlord consents to the Sublease or
Assignment within such fifteen (15) day period, Tenant may thereafter within
sixty (60) days after Landlord's consent enter into such Assignment or Sublease
with such approved assignee or subtenant upon the terms and conditions set forth
in the notice furnished by Tenant to Landlord pursuant to Section 14.2. No
Assignment or Sublease shall be binding on Landlord until Tenant delivers an
executed copy of such Assignment or Sublease to Landlord.

          14.4 No Release. No consent by Landlord to any Assignment or Sublease
by Tenant shall relieve Tenant of any obligation to be performed by Tenant under
this Lease, whether arising before or after the Assignment or Sublease. The
consent by Landlord to any Assignment or Sublease shall not relieve Tenant from
the obligation to obtain Landlord's express consent to any other Assignment or
Sublease. Any Assignment or Sublease that fails to comply with this Article 14
shall be void and, at the option of Landlord, shall constitute an Event of
Default by Tenant under this Lease. The acceptance of Base Rent or Additional
Charges by Landlord from a proposed assignee or subleasee shall not constitute
consent to such Assignment or Sublease by Landlord.

          14.5 Affiliates. Occupancy of all or part of the Premises by a parent,
subsidiary or affiliated companies of Tenant or Tenant's parent or Tenant's
subsidiary shall not be deemed an assignment or subletting provided that such
parent, subsidiary or affiliated companies were not formed as a subterfuge to
avoid the obligation of this Article 14.

     15.  UTILITIES AND SERVICES
          ----------------------

          15.1 Landlord's Obligations. Landlord agrees to furnish to the
Premises, subject to the rules and regulations of the Building, (a) at all
times, electricity for normal lighting and fractional horsepower office machines
in an amount not to exceed .025 KWH per square foot per normal business day,
nonattended freight and passenger elevator service, and water for lavatory and
drinking purposes, and (b) from 7:00 a.m. to 6:00 p.m. Monday through Friday,
except for generally recognized business holidays in San Mateo, California, heat
and air-conditioning required in Landlord's judgment for the comfortable use and
occupation of the Premises. Landlord may reduce elevator service on evenings,
weekends and holidays. Landlord shall provide sufficient janitorial service for
general office use, as reasonably

                                      10.
<PAGE>

determined by Landlord. Landlord shall not be liable for, and Tenant shall not
be entitled to, any reduction of Base Rent by reason of (x) the installation,
use of or interruption of use of any equipment in connection with the furnishing
of any of the foregoing services (y) the failure to furnish or delay in
furnishing any of the foregoing services when such failure is caused by
accident, breakage, repairs, strikes, lockouts or other labor disturbances or
labor disputes of any character, or by any other cause, similar or dissimilar,
beyond the reasonable control of Landlord or by the making of any repairs or
improvements to the Premises or to the Building or any portion of either, or (z)
the limitation, curtailment, rationing or restrictions on use of water,
electricity, gas or any other utility servicing the Premises or the Building by
any utility or governmental agency. If Tenant requests additional or after-hours
heating or air conditioning, Landlord shall provide such service provided that
Tenant pays Landlord's reasonable charge for such services. Tenant further
agrees to cooperate fully at all times with Landlord and to abide by all
regulations and requirements which Landlord may prescribe (including, without
limitation, maintaining all window coverings in the Premises closed whenever the
system is in operation) for the proper function and control of the air
conditioning system.

          15.2 Restrictions. Tenant shall not use any apparatus or device in the
Premises using in excess of 120 volts, that will in any way increase the amount
of electricity usually furnished or supplied for the use of the Premises as
general office space; nor connect with electric current, except through existing
electrical outlets in the Premises, any apparatus or device, for the purpose of
using electric current. If the Tenant shall require water or electric current in
excess of the amount usually furnished or supplied for the use of the Premises
as general office space, Tenant shall first procure the prior consent of
Landlord to the use of such excess water or electric current, which consent
Landlord may refuse in its sole discretion. Landlord may condition its consent
upon Tenant's agreement to reimburse Landlord monthly for the excess cost
thereof, based upon an estimate agreed upon by Landlord and Tenant, or, if the
parties fail to agree, as established by an independent licensed engineer.

     16.  DEFAULT
          -------

          16.1 Events of Tenant's Default. Tenant shall be in default of its
obligations under this Lease if any of the following events occurs (an "Event of
Tenant's Default"):

               (a) Tenant shall have failed to pay Base Rent or Additional
Charges when due, and such failure is not cured within three (3) days after
delivery of written notice from Landlord specifying such failure to pay; or

               (b) Tenant shall have failed to perform any term, covenant, or
condition of this Lease except those requiring the payment of Base Rent or
Additional Charges, and Tenant shall have failed to cure such breach within ten
(10) days after written notice from Landlord specifying the nature of such
breach where such breach could reasonably be cured within said ten (10) day
period, or if such breach could not be reasonably cured within said ten (10) day
period, Tenant shall have failed to commence such cure within said ten (10) day
period and thereafter continue with due diligence to prosecute such cure to
completion within such time period as is reasonably needed but not to exceed
thirty (30) days from the date of Landlord's notice; or

               (c) Tenant shall have sublet the Premises or assigned its
interest in the Lease in violation of the provisions contained in Section 14; or

               (d) Tenant shall have abandoned the Premises or left the Premises
substantially vacant; or

               (e) The occurrence of the following: (i) the making by Tenant of
any general arrangements or assignments for the benefit of creditors; (ii)
Tenant becomes a "debtor" as defined in 11 U.S.C. Section 101 or any successor
statute thereto (unless, in the case of a petition filed against Tenant, the
same is dismissed within 60 days); (iii) the appointment of a trustee or
receiver to take possession of substantially all of Tenant's assets located at
the Premises or of Tenant's interest in this Lease, where possession is not
restored to Tenant within thirty (30) days; or (iv) the attachment, execution or
other judicial seizure of substantially all of Tenant's assets located at the
Premises or of Tenant's interest in this Lease, where such seizure is not
discharged within thirty (30) days; provided, however, in the event that any

                                      11.
<PAGE>

provision of this Section 16.1 (e) is contrary to any applicable Law, such
provision shall be of no force or effect; or

               (f) Tenant shall have failed to deliver documents required of
Tenant pursuant to Section 11 or 21 within the time periods specified therein.

The notice periods provided for in this Section 16.1 are intended to satisfy any
and all notice requirements imposed on Landlord by law (including, without
limitation, California Code of Civil Procedure Section 1161) and are not in
addition to any such requirements.

          16.2 Landlord's Remedies. If an Event of Tenant's Default occurs,
Landlord shall have the following remedies in addition to all other rights and
remedies provided by any Law or otherwise provided in this Lease, to which
Landlord may resort cumulatively or in the alternative:

               (a) Landlord shall have the remedy described in Civil Code
Section 1951.4, which provides that, when a tenant has the right to sublet or
assign (subject only to reasonable limitations), the Landlord may continue the
lease in effect after the tenant's breach and abandonment and recover rent as
its become due. Accordingly, if Landlord does not elect to terminate this Lease
on account of an Event of Tenant's Default, Landlord may enforce all of
Landlords rights and remedies under this Lease, including the right to recover
all Rent due under this Lease as it becomes due.

               (b) Landlord may terminate Tenant's right to possession of the
Premises at any time by giving written notice to that effect, and relet the
Premises or any part thereof. Tenant shall be liable immediately to Landlord
for all costs Landlord incurs in relating the Premises of any part thereof,
including, without limitation, broaker's commisions, expenses of cleaning and
redecorating the Premises required by the releting and like costs. Reletting may
be for a period shorter of longer than the remaining term of this Lease. No act
by Landlord other than giving written notice to Tenant shall terminate this
Lease. Acts of maintenance, efforts to reler the Premises or the appointment of
a receiver on Landlord's initiative to protect Landlord's interest under this
Lease shall not constitute a termination:

                   (1) The worth at the time of award of the amount by which the
unpaid Rent for the balance of the term after the time of award exceeds the
amount of such rental loss that Tenant proves could be reasonably avoided,
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 (1%); and

                   (2) Any other amount necessary to compensate Landlord for all
detriment proximately caused by Tenant's failure to perform Tenant's obligations
under this Lease, or which in the ordinary course of things would be likely to
result therefrom, including the following: (i) expenses for cleaning, repairing
or restoring the Premises; (ii) expenses for altering, remodeling or otherwise
improving the Premises for the purpose of reletting, including installation of
leasehold improvements (whether such installation be funded by a reduction of
rent, direct payment or allowance to a new tenant, or otherwise); (iii) broker's
fees, advertising costs and other expenses of reletting the Premises; (iv) costs
of carrying the Premises, such as taxes, insurance premiums, utilities and
security precautions; (v) expenses in retaking possession of the Premises; and
(vi) attorneys' fees and court costs incurred by Landlord in retaking possession
of the Premises and in releasing the Premises or otherwise incurred as a result
of Tenant's default.

               (c) Nothing in this Section 16.2 shall limit Landlord's right to
indemnification from Tenant as provided in Sections 17.3. Any notice given by
Landlord in order to satisfy the requirements of this Section 16.2 shall also
satisfy the notice requirements of California Code of Civil Procedure Section
1161 regarding unlawful detainer proceedings.

          16.3 Waiver. One party's consent to or approval of any act by the
other party requiring the first party's consent or approval shall not be deemed
to waive or render unnecessary the first party's consent to or approval of any
subsequent similar act by the other party. The receipt by Landlord of any rent,
payment, interest or late charge with or without knowledge of the breach of any
other provision hereof shall not be deemed a waiver of any such breach unless
such waiver is in writing and signed by Landlord. No delay or omission in the
exercise of any right or remedy accruing to either party upon any breach by the

                                      12.
<PAGE>

other party under this Lease shall impair such right or remedy or be construed
as a waiver of any such breach theretofore or thereafter occurring. The waiver
by either party of any breach of any provision of this Lease shall not be deemed
to be a waiver of any subsequent breach of the same or of any other provisions
herein contained.

           16.4  Limitation on Exercise of Rights. At any time that an Event of
Tenant's Default has occurred and remains uncured, (i) Landlord may deny or
withhold any consent or approval requested of it by Tenant which Landlord would
otherwise be obligated to give; and (ii) Tenant may not exercise any option to
extend, right to terminate this Lease, or other right granted to it by this
Lease which would otherwise be available to it.

           16.5  Waiver by Tenant of Certain Remedies. Tenant waives the
provisions of Sections 1932(1), 1941 and 1942 of the California Civil Code and
any similar or successor law regarding Tenant's right to terminate this Lease or
to make repairs and deduct the expenses of such repairs from the rent due under
this Lease. Tenant hereby waives any right of redemption or relief from
forfeiture under the laws of the State of California, or under any other present
or future law, including the provisions of Sections 1174 and 1179 of the
California Code of Civil Procedure.

           16.6  Remedies Cumulative. All rights, privileges and remedies of the
parties are cumulative and not alternative or exclusive to the extent permitted
by law except as otherwise provided herein.

           16.7  Landlord's Default. Landlord shall ot be deemed to be in
default in the performance of any obligation required to be performed by it
hereunder unless and until it has failed to perform such obligation within
thirty (30) days after receipt of written notice by Tenant to Landlord
specifiying the nature of such that more than thirty (30) days are required for
its performance, then Landlord shall not be deemed to be in default if it shall
commence sucj [erfpr,amce within such thirty (30) day period and thereafter
diligently prosecute the same to completion.

      17.  LIABILITY OF LANDLORD; INDEMNITY BY TENANT
           ------------------------------------------

           17.1  Limitation on Landlord's Liability. Landlord shall not be
liable to Tenant, nor shall Tenant be entitled to terminate this Lease or to any
abatement of Rent, for any injury to Tenant or any parties affiliated with
Tenant, damage to the property of Tenant or any parties affiliated with Tenant,
or loss to Tenant's business resulting from any cause, including without
limitation any: (i) failure, interruption or installation of any HVAC or other
utility system or service; (ii) failure to furnish or delay in furnishing any
utilities or services when such failure or delay is caused by fire or other
peril, the elements, labor disturbances of any character, or any other accidents
or other conditions beyond the reasonable control of Landlord; (iii) limitation,
curtailment, rationing or restriction on the use of water or electricity, gas or
any other form of energy or any services or utility serving the Complex; (iv)
vandalism or forcible entry by unauthorized persons or the criminal act of any
person; or (v) penetration of water into or onto any portion of the Building
through roof leaks or otherwise. Notwithstanding the foregoing but subject to
Sections 17.2 and 18.3, Landlord shall be liable for any such injury, damage or
loss which is proximately caused by Landlord's willful misconduct or gross
negligence of which Landlord has actual notice and a reasonable opportunity to
cure but which it fails to so cure.

           17.2. Limitation on Tenant's Recourse. If Landlord is a corporation,
trust, partnership, joint venture, unincorporated association or other form of
business entity: (i) the obligations of Landlord shall not constitute personal
obligations of the officers, directors, trustees, partners, joint ventures,
members, owners, stockholders, or other principals or representatives of such
business entity; and (ii) Tenant shall not have recourse to the assets of such
officers, directors, trustees, partners, joint ventures, members, owners,
stockholders, principals or representatives except to the extent of their
interest in the Premises. Notwithstanding anything to the contrary in this
Lease, Tenant shall have recourse only to the interest of Landlord in the
Premises for the satisfaction of each and every remedy of Tenant in the event of
default by Landlord hereunder; such exculpation of personal liability is
absolute and without exception whatever

           17.3  Indemnification of Landlord. Tenant shall hold harmless,
indemnify, protect and defend Landlord, and its employees, agents, contractors,
directors, partners, shareholders, officers, advisors, consultants and lenders,
with legal counsel satisfactory to Landlord from all liability, penalties,
losses,

                                      13.
<PAGE>

damages, costs, expenses (including attorneys' fees and court costs), causes of
action, claims and/or judgments arising by reason of any death, bodily injury,
personal injury or property damage resulting from (i) any cause or causes
whatsoever (other than the willful misconduct or gross negligence of Landlord of
which Landlord has had notice and a reasonable time to cure, but which Landlord
has failed to cure) occurring in or about or resulting from an occurrence in or
about the Premises, the Complex or associated parking areas and walkways during
the Lease Term; (ii) the negligence or willful misconduct of Tenant or any party
affiliated with Tenant, wherever the same may occur; or (iii) an Event of
Tenant's Default. The provisions of this Section 17.3 shall survive the
expiration or sooner termination of this Lease.

          17.4 Notice of Claim or Suit. Tenant shall promptly notify Landlord of
any claim, action, proceeding or suit instituted or threatened against Tenant of
which Tenant received notice or of which Tenant acquires knowledge and which
names Landlord as a party thereto.

          17.5 Waiver of Jury Trial. Landlord and Tenant each acknowledges that
it is aware of and has had the advice of counsel of its choice with respect to
its rights to trial by jury, and each party does hereby expressly and knowingly
waive and release all such rights to trial by jury in any action, proceeding or
counterclaim brought by either party hereto against the other (and/or against
its officers, directors, employees, agents, or subsidiary or affiliated
entities) on any matters whatsoever arising out of or in any way connected with
this Lease, Tenant's use of occupancy of the Premises, and/or any claim of
injury or damage.

          17.6 Sale of Premises. In the event of any sale or transfer of the
Premises, the seller, transferor or assignor shall be and hereby is entirely
freed and relieved of all agreements, covenants and obligations of Landlord
thereafter to be performed and it shall be deemed and construed without further
agreement between the parties or their successors in interest or between the
parties and the purchaser, transferee or assignee on any such sale, transfer or
assignment that such purchaser, transferee or assignee has assumed and agreed to
carry out any and all agreements, covenants and obligations of Landlord
hereunder.

      18. INSURANCE
          ---------

          18.1 Tenant's Insurance. Tenant shall procure at its cost and expense
and keep in effect during the Term broad form comprehensive general liability
insurance, including, without limitation, contractual liability for Tenant's
indemnity obligation contained in Section 17 and specific coverage of risks
arising out of any activities of Tenant pursuant to Articles 7 and 8, with a
combined single limit of liability in an amount equal to the amount set forth in
the Summary. Such coverage shall be in a comprehensive general liability form
with at least the following endorsements to the extent such endorsements are
generally available: (i) deleting any employee exclusion on personal injury
coverage, (ii) including employees as additional insureds, (iii) providing for
blanket contractual coverage and broad form property damage coverage, (iv)
deleting any liquor liability exclusions, and (v) providing for coverage of
employees' automobile non ownership liability. Such insurance shall name
Landlord and any other party designated by Landlord as an additional insured,
shall be carried by companies licensed to do business in California and which
have a general policy holders' rating of not less than "A" and a financial
rating of not less than Class "X" as set forth in the most current issue of
Best's Insurance Guide", shall specifically include the liability assumed
hereunder by Tenant, shall provide that it is primary insurance and not in
excess over or contributory with any other valid, existing and applicable
insurance covering the same loss carried by Landlord or any other party, shall
provide for severability of interests, shall further provide that an act or
omission of one of the named insiders which would void or otherwise reduce
coverage shall not reduce or void the coverage as to any insured, shall afford
coverage for all claims based on acts, omissions, injury or damage which
occurred or arose (or the onset of which occurred or arose) in whole or part
during the policy period, and shall provide that Landlord will receive thirty
(30) days' written notice from the insurer prior to any cancellation or change
of coverage. Tenant shall deliver policies of such insurance or certificates
thereof to Landlord on or before the Commencement Date, and thereafter at least
thirty (30) days before the expiration dates of expiring policies; and in the
event Tenant shall fail to procure such insurance, or to deliver such policies
or certificates, Landlord may, at its option, procure same for the account of
Tenant, and the cost thereof shall be paid to Landlord within five (5) days
after delivery to Tenant of bills therefore. Tenant shall be responsible, at its
cost and expense, for separately insuring Tenant's property. The amounts of such
insurance shall be subject to adjustment from time to time as requested by
Landlord based upon Landlord's determination of the amount of such insurance
generally required for comparable tenants,

                                      14.
<PAGE>

premises and buildings in the general geographic location of the Building or
required by a lender with an interest in the Building.

          18.2 Landlord's Insurance. Landlord shall maintain all risk property
insurance covering the estimated replacement cost of the Building. Landlord may,
but is not obligated to, maintain such other insurance and additional coverages
as it may deem necessary, including, but not limited to, commercial liability
insurance and rent loss insurance. The cost of such insurance to Landlord shall
be deemed an Insurance cost. The Building may be included in a blanket policy
(in which case the cost of such insurance allocable to the Building wilt be
determined by Landlord based upon the insurer's cost calculations).

          18.3 Waiver of Subrogation. Notwithstanding anything to the contrary
contained herein, to the extent of insurance proceeds received with respect to
the loss, Landlord and Tenant each hereby waives any right of recovery against
the other party and against any other party maintaining a policy of insurance
with respect to the Building or any portion thereof or the contents of any of
the same, for any loss or damage maintained by such other party with respect to
the Building, or the Premises or any portion thereof or the contents of the same
or any operation therein, whether or not such a loss is caused by the fault or
negligence of such other party.

      19. ACCESS TO PREMISES
          ------------------

          Landlord, its agents and representatives shall have the right to enter
the Premises at all reasonable times and, except in cases of emergency, after
giving Tenant reasonable notice for any purpose deemed necessary or desirable by
Landlord. Rent shall not abate as a result thereof. Landlord shall use
reasonable efforts to minimize any interference with Tenant's use of the
Premises for its normal business purposes. Tenant hereby waives any claim for
damages for any injury or inconvenience to or interference with Tenant's
business, any loss of occupancy or quiet enjoyment of the Premises or any other
loss occasioned thereby excepting the negligence or willful misconduct of
Landlord, agents, servants, employees, licensees or contractors. No entry by
Landlord under any circumstances shall be construed or deemed to be a forcible
or unlawful entry into or a detainer of, the Premises, or an eviction, actual or
constructive, of Tenant from the Premises or any portion thereof. Tenant
acknowledges that in the event the Lease is not renewed, that the Landlord shall
have the right to show prospective tenants the Leased premises during the last
ninety (90) days of the Lease term without prior notice to Tenant.

      20. NOTICES
          -------

          Notices or other communications under this Lease shall be effective
only if given in writing, sent by certified mail, by facsimile telecopy or by
courier service with a return receipt requested or delivered personally: (a) to
Tenant (i) at Tenant's address set forth in the Summary, if sent prior to
Tenant's taking possession of the Premises, or (ii) at the Premises, if sent
subsequent to Tenant's taking possession of the Premises, or (b) to Landlord at
Landlord's address set forth in the Summary, or (c) to either Landlord or Tenant
at such other address as either Landlord or Tenant may designate as its new
address for such purpose by notice given to the other in accordance with the
provisions of this Article. A notice shall be deemed to have been given (i) on
the third (3rd) business day after mailing of such notice was deposited in the
United States mail, postage prepaid, addressed to the party at the foregoing
address, (ii) when delivered if given by personal delivery; and in all other
cases when actually received at the address for notices set forth above.

      21. TENANT'S CERTIFICATE
          --------------------

          Tenant, at any time and from time to time upon not less than ten (10)
day's prior written notice from Landlord, will execute, acknowledge and deliver
to Landlord a certificate stating that this Lease is in full force and effect,
specifying the dates to which rent has been paid thereunder and certifying to
such other matters as Landlord may reasonably request. Any such certificate may
be relied upon by Landlord and by any prospective purchaser or mortgagee
considering the purchase of or a loan on all or any part of the Building or any
interest therein.

                                      15.
<PAGE>

      22. TAX ON TENANT'S PERSONAL PROPERTY
          ---------------------------------

          At least ten (10) days prior to delinquency, Tenant shall pay all
taxes levied or assessed upon Tenant's Property and shall deliver satisfactory
evidence of such payment to Landlord, If, as determined by Landlord, the
assessed value of Landlord's property is increased by the inclusion therein of a
value placed upon Tenant's Property, Tenant shall promptly pay such increased
amount to Landlord.

      23. SECURITY DEPOSIT
          ----------------

          Upon execution of this Lease, Tenant shall pay to Landlord, Tenant's
security deposit for the faithful performance of all terms, covenants and
conditions of this Lease in the amount specified in the Summary. Landlord may
apply any part of the security deposit to: (i) remedy any default by Tenant in
the payment of rent; (ii) repair damage to the Premises caused by Tenant; (iii)
clean the Premises upon termination of the Lease; and (iv) remedy any other
default of Tenant to the extent provided by Law. Tenant hereby waives the
restriction contained in California Civil Code Section 1950.7. Should Landlord
use any portion of the security deposit, Tenant shall forthwith replenish the
security deposit to the original amount. If Tenant shall fully and faithfully
perform every provision of this Lease, the remaining balance of the security
deposit, if any, shall be returned to Tenant (or, at Landlord's option, to the
last assignee of Tenant's interest hereunder) within thirty (30) days after the
Expiration Date. In the event of termination of Landlord's interest in this
Lease, Landlord may transfer the security deposit to Landlord's successor in
interest and, upon such transfer, Landlord shall be relieved of any and all
liability for or obligation with respect to the security deposit. Landlord shall
not be deemed a Trustee of the Security Deposit, may use the Security Deposit in
Landlord's business, one shall not be required to segregate it from its general
accounts.

     24. LANDLORD'S OPTION TO RELOCATE TENANT
         ------------------------------------

         24.1 Substituted Premises. Landlord may relocate Tenant to any other
space in the Complex at any time during the term of this Lease provided that:
(i) Landlord provides Tenant with prior written notice thereof ("Relocation
Notice") at least thirty (30) days in advance; and (ii) the square footage of
space to which Tenant is relocated ("Relocation Premises") equals or exceeds the
square footage of the Premises. In the event that Landlord delivers a Relocation
Notice to Tenant, Tenant shall deliver to Landlord within two (2) business days
of receipt thereof written notice ("Confirmation Notice") to Landlord confirming
Tenant's receipt of the Relocation Notice and acknowledging the relocation of
the Premises to the Relocation Premises. In the event that Landlord exercises
its right to move Tenant to a Relocation Premises, Landlord shall, at Landlord's
sole cost and expense, (a) construct tenant improvements in the Relocation
Premises which are substantially similar to the configuration of the tenant
improvements in the Premises, taking any differences in configuration between
the Premises and Relocation Premises into account; and (b) move Tenant's
inventory, furniture and personal property to the Relocation Premises.

Tenant shall provide Landlord with the current inventory or printing which is to
be replaced. All printing to be done by a printer chosen by Bayshore Corporate
Center. During the period of time commencing upon Tenant's receipt of the
Relocation Notice and ending upon Tenant's receipt of the Completion Notice (as
defined below), Tenant shall continue to conduct its business in the Premises to
the maximum extent possible. In no event shall Tenant be entitled to, and Tenant
hereby waives, any claim for abatement of Rent, loss of profits or any other
amount due to Landlord's relocation of Tenant to the Relocation Premises.

          24.1a Overhead Costs. Landlord shall, at Landlords sole expense, pay
the expense of preparing the relocation premises to (a) a similar construction
of current premises, (b) moving of tenants inventory, furniture and personal
property, (c) relocation of telephone system, computer systems and wiring, and
(d) cost of replacement stationary and other associated printing upon Tenant
providing inventory of current stationary, and (e) any other reasonably
associated fees.

          24.2 Amendment. In the event that Landlord relocates Tenant pursuant
to this Section 24, Tenant's occupancy of the Relocation Premises shall be upon
all of the same terms and conditions (including rent) that applied to the
Premises. If requested by landlord, Tenant shall promptly execute an amendment
to the Lease confirming the relocation of Tenant to the Relocation Premises and
showing the floor plan therefor.

                                      16.
<PAGE>

            24.3 Landlord's Termination Right. In the event that Tenant shall
fail to either: (i) deliver to Landlord the Confirmation Notice when due; (ii)
surrender the Premises upon receipt of the Completion Notice; or (iii) commence
business at the Relocation Premises at the end of the Move-In Period, Landlord
may immediately terminate this Lease and all of the obligations and liabilities
of Landlord hereunder upon written notice thereof to Tenant and, thereafter,
Landlord shall have all rights and remedies under the Lease and applicable Law.

      25.   GUARANTOR
            ---------

            The obligations of Tenant under this Lease shall be guaranteed in
their entirety by the Guarantor described on the "Summary Page" of the Basic
Lease Provisions. If Guarantor is or becomes bankrupt or insolvent, makes an
assignment for the benefit or creditors, or institutes or is the subject of any
proceeding under the Bankruptcy Act or other similar law for the protection of
creditors (or, if Guarantor is a partnership or consists of more than one person
or entity, if any partner of the partnership or such other person or entity is
or becomes bankrupt or insolvent, institutes any such proceeding, or makes an
assignment for the benefit or creditors), then Landlord shall have the option to
terminate this Lease upon thirty (30) days written notice unless Tenant, within
such thirty (30) day period, provides Landlord with either (i) a substitute or
additional guarantor satisfactory to Landlord and any Lender, or (ii) adequate
assurance of the performance of each and every obligation of Tenant hereunder,
satisfactory to Landlord and such Lender; provided, however, that no such
termination of this Lease shall become effective without the prior written
consent of such Lender.

      26.   SURRENDER OF LEASED PREMISES
            ----------------------------

            26.1 Tenant shall, at least ninety (90) days before the last day of
the term hereof, give to Landlord a written notice of intention to surrender the
leased premises on that date, but nothing contained herein shall be construed as
an extension of the term hereof or as consent of Landlord to any holding over by
Tenant. At the end of the term or any renewal thereof or other sooner
termination of this Lease, Tenant will peaceably deliver up to the Landlords
possession of the leased premises, together with all improvements or additions
upon or belonging to the same, by whosoever made, in the same condition as
received, or first installed, ordinary wear and tear and damage by fire,
earthquake, act of God or the elements alone excepted. Tenant may, upon the
termination of this Lease, remove, at Tenants sole cost, all trade fixtures
installed by Tenant, title to which shall be in Tenant until such termination,
repairing any damage to the leased caused by such removal. Any of Tenants
personal property and trade fixtures not removed by Tenant at the end of the
term or other sooner termination of this Lease shall be deemed abandoned by the
Tenant if Landlord so elects, and Landlord shall remove, store and disposing of
Tenants abandoned personal property and trade fixtures. Tenant shall indemnify
Landlord against any loss or liability resulting from delay by Tenant in so
surrendering the leased premises, including without limitation, any claims made
by any succeeding Tenant founded on such delay. The voluntary or other surrender
of this lease by Tenant, or a mutual cancellation thereof, shall not work a
merger, and shall, at the option of Landlord, terminate all or any existing
subleases or subtenancies, or may, at the option of Landlord, operate as an
assignment to it of any or all such subleases or subtenancies.

            26.2 If Tenant does not give Landlord ninety (90) days written
notice then Tenant will be obligated to pay rent ninety (90) days from when
written notice is given, unless the space has been leased to a new Tenant. In
the event Landlord leases the space to a new Tenant during the ninety (90) day
period, then Tenant will be released from the Lease obligation as of the date of
commencement of the new Lease.

      27.   MISCELLANEOUS
            -------------

            27.1 The words "Landlord" and "Tenant" as used herein shall include
the plural as well as the singular. If there is more than one Tenant, the
obligations under this Lease imposed on Tenant shall be joint and several. The
captions preceding the articles of this Lease have been inserted solely as a
matter of convenience and such captions in no way define or limit the scope or
intent of any provision of this Lease.

            27.2 The terms, covenants and conditions contained in this Lease
shall bind and inure to the benefit of Landlord and Tenant and, except as
otherwise provided herein, their respective personal representatives and
successors and assigns: provided, however, that upon the sale, assignment or
transfer by

                                      17.
<PAGE>

Landlord named herein (or by any subsequent landlord) of its interest in the
Building as owner or Tenant, including any transfer by operation of law,
Landlord (or such subsequent landlord) shall be relieved from all subsequent
obligations and liabilities arising under this Lease subsequent to such sale,
assignment or transfer.

          27.3 Any provision of this Lease which shall prove to be invalid,
void, illegal or unenforceable shall in no way affect, impair or invalidate any
other provisions of this Lease, and such provisions and this Lease shall remain
in full force and effect.

          27.4 This Lease shall be construed and enforced in accordance with the
laws of the State of California.

          27.5 This instrument, including the exhibits hereto, which are made a
part of this Lease, contains the entire agreement between the parties and all
prior negotiations and agreements are merged herein. Tenant hereby acknowledges
that neither Landlord nor Landlord's agents have made any representations or
warranties with respect to the Premises, the Building or this Lease except as
expressly set forth herein.

          27.6 In the event of any action or proceeding brought by either party
against the other under this Lease, the prevailing party shall be entitled to
recover all costs and expenses, including its attorneys' fees, in such action or
proceeding in such amount as the court may adjudge reasonable. The prevailing
party shall be determined by the court based upon an assessment of which party's
major arguments made or positions taken in the proceedings could fairly be said
to have prevailed over the other party's major arguments or positions on major
disputed issues in the court's or arbitrator's decision. If Landlord or Tenant,
through no fault of its own, is named as defendant in any suit brought against
Landlord or Tenant in connection with or in any way arising out of this Lease or
Tenant's use of occupancy of the Premises, Landlord or Tenant shall pay
Landlord's or Tenant's costs and expenses, including, without limitation,
reasonable attorneys fees, incurred in such suit or action.

          27.7 If Landlord is unable to fulfill or is delayed in fulfilling any
of Landlord's obligations under this Lease, by reason of acts of God, accidents,
repairs, labor disputes, inability to obtain utilities or materials or by any
other reason beyond Landlord's reasonable control, then no such inability or
delay by Landlord shall constitute an actual or constructive eviction, in whole
or in part, or entitle Tenant to any abatement or diminution of Base Rent or
Additional Charges, or relieve Tenant from any of its obligations under this
Lease, or impose any liability upon Landlord or its agents by reason of
inconvenience, annoyance, interruption, injury or loss to or interference with
Tenant's business or use and occupancy or quiet enjoyment of the Premises or any
loss or damage occasioned thereby. Tenant hereby waives and releases any right
to terminate this Lease under Section 1932 (1) of the California Civil Code or
any similar law, statute or ordinance now or hereafter in effect, provided
Landlord make all reasonable efforts within a timely manner to assist Tenant in
relocating to suitable space within the project.

          27.8 If Tenant shall retain possession of the Premises or any part
thereof without Landlord's consent following the expiration or sooner
termination of this Lease for any reason, then Tenant shall pay to Landlord one
hundred and seventy-five percent (175%) of the Base Rent in effect immediately
prior to the date of such expiration or termination, subject to adjustment as
provided in Article 4.

          27.9 In the event of any default by Landlord hereunder, Tenant shall
look only to Landlord's interest in the Building and the land on which the
Building is located for the satisfaction of Tenant's remedies; and no other
property or assets of Landlord or any partner, member, officer or director
thereof, disclosed or undisclosed, shall be subject to levy, execution or other
enforcement procedure for the satisfaction of Tenant's remedies under or with
respect to this Lease.

          27.10 Time is of the essence of this Lease and each and all of its
provisions in which performance is a factor.

          27.11 Tenant shall faithfully observe and comply with the rules and
regulations attached to this Lease as Exhibit C and all modifications thereof
                                      ---------
and additions thereto from time to time put into effect by Landlord (the "Rules
and Regulations"). Landlord shall have no duty to enforce the Rules and

                                      18.
<PAGE>

Regulations by any other tenant or occupant. In the event of any conflict
between the terms and conditions of this Lease and the Terms and conditions of
the Rules and Regulations, this Lease shall control.

          27.12 If Tenant signs this Lease as a corporation or a partnership,
each of the persons executing this Lease on behalf of Tenant does hereby
covenant and warrant that Tenant is a duly authorized and existing entity, that
Tenant has full right and authority to enter into this Lease, and that each and
both of the persons signing on behalf of Tenant are authorized to do so. Upon
Landlord's request, Tenant shall provide Landlord with evidence reasonably
satisfactory to Landlord confirming the foregoing covenants and warranties.

          27.13 Upon Tenant's paying the Base Rent and Additional Charges and
observing and performing all of the provisions of this Lease, Tenant shall be
entitled to the quiet enjoyment of the Premises for the entire Term, subject to
the provisions of this Lease.

          27.14 Tenant covenants and agrees that no diminution of light or view
by any structure that may hereafter be erected (whether or not by Landlord)
shall entitle Tenant to any reduction of the Base Rent or Additional Charges
under this Lease, result in any liability of Landlord to Tenant, or in any other
way affect this Lease or Tenant's obligations hereunder.

          27.15 Parking: Throughout the term hereof, Tenant shall have the right
to use for its employees parking space as available in the parking areas in and
about the Building. The parking areas shall be used on a non-exclusive basis
with other Tenants of the Building. Parking for Tenants invitees shall be
available in said parking areas on a non-exclusive, first-come, first-served
basis with invitees of other Tenant of the Building.

          27.16 ADA Compliance: Landlord will be responsible for any work
required to bring the premises into ADA compliance.

                                      19.
<PAGE>

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

LANDLORD:                CORNERSTONE PROPERTIES I, LLC

Dated: 8/5/99            By: /s/ Steve Kaufman
       ------                -----------------
                         Name: Steve Kaufman

TENANT:                  AVANTGO, INC.

Dated: 8/5/99            By: /s/ Hans Upson
       ------                --------------
                         Name: Hans Upson

                                      20.
<PAGE>

                                                       Bayshore Corporate Center

                                   EXHIBIT B
                                   ---------

                      DEFINITIONS OF REAL ESTATE TAXES,
                             BUILDING EXPENSES AND
                             COMMON AREA EXPENSES

       "Real Estate Taxes" means all taxes, assessments and charges levied upon
or with respect to the Building or any personal property of Landlord used in the
operation thereof, or Landlord's interest in the Building or such personal
property. Real Estate Taxes shall include, without limitation, all general real
property taxes and general and special assessments, charges, fees, or
assessments for transit, housing, police, fire or other governmental services or
purported benefits to the Building or the occupants thereof, service payments in
lieu of taxes, and any tax, fee or excise on the act of entering into this Lease
or any other lease of space in the Building, or on the use or occupancy of the
Building or any part thereof, or on the rent payable under any lease or in
connection with the business of renting space in the Building, that now or
hereafter levied or assessed against Landlord by the United States of America,
the State of California or any political subdivision thereof, public
corporation, district, or any other political or public entity, and shall also
include any other tax, fee or other excise, however described, that may be
levied or assessed as a substitute for, or as an additional to, in whole or in
part, any other Real Estate Taxes whether or not now customary or in the
contemplation of the parties. Real Estate Taxes shall not include franchise,
transfer, inheritance, or capital stock taxes or income taxes, measured by the
net income of Landlord from all sources unless, due to a change in the method of
taxation, any of such taxes is levied or assessed against Landlord as a
substitute for, or as an addition to, in whole or in part, any other tax that
would otherwise constitute a Real Estate Tax. Real Estate Taxes shall also
include reasonable legal fees, costs, and disbursements incurred in connection
with proceedings to contest, determine, or reduce Real Estate Taxes.

       "Building Expenses" means the total cost and expenses paid or incurred by
Landlord in connection with the management, operation, maintenance and repair of
the Buildings, including without limitation: (i) the cost of air conditioning,
electricity, steam, water, heating, mechanical, telephone, utilities (ii) the
cost of repairs, replacements and all labor and material costs related thereto,
and the cost of general maintenance, cleaning and service contracts and the cost
of all supplies, tools and equipment required in connection therewith, (iii)
wages, salaries, payroll taxes and other labor costs and employee benefits, (iv)
management fees, (v) fees, charges and other costs of all independent
contractors engaged by Landlord, (vi) accounting and legal expenses, (vii)
security protection, (viii) depreciation on personal property, including,
without limitation, carpeting in public corridor and common areas and window
coverings provided by Landlord, (ix) the fair market rental value of all offices
in the Building for the property manager and related management and operations
personnel, (x) the cost of any capital improvements made in the building after
completion of its construction as a labor saving or energy saving device or to
effect other economics in the operation or maintenance of the Building, or made
to the Building after the date of this Lease that are required under any
governmental law or regulations that was not applicable to the Building at the
time that permits for the construction thereof were obtained such cost to be
amortized over such reasonable period as Landlord shall determine, together with
interest on the unamortized balance at the rate of ten percent (10%) per annum
or such higher rate as may have been paid by Landlord on funds borrowed for the
purpose of construction such capital improvements, (xi) the cost of contesting
the validity or applicability of any governmental enactments which may affect
operating expenses, (xii) maintenance and repair of the roof of the building and
the structural parts of the Building, (xiii) fees for licenses and permits
required for the operation of the Building and Common Area and (xiv) any other
expenses of any kind whatsoever reasonably incurred in connection with the
management, operation, maintenance and repair of the Building (other than Real
Estate Taxes, Insurance expenses and any services for which Landlord is
separately and directly reimbursed by tenant or other tenants in the Building).
Building Expenses of a variable nature shall be adjusted to reflect ninety-five
(95%) occupancy of the Building during any period in which the Building is not
at least ninety-five (95%) occupied; provided, however, no such adjustment shall
result in an inequitable allocation of Building Expenses to Tenant.

       "Common Area Expenses" means the total cost and expenses paid or incurred
 by Landlord in connection with the management, operation and maintenance of the
 Common Area (as defined in Section 5.2), including without limitation each of
 those items specified under "Building Expenses" to the extent applicable to the
 Common Area.

<PAGE>

                                                       Bayshore Corporate Center

       "Insurance Expenses" shall mean all premiums and costs and expenses for
all policies of insurance which may be obtained by Landlord in its discretion
for (a) the Premises, Building and the Common Areas of the Complex, or any
blanket policies which include the Building or Complex, covering damage thereto
and loss of rents caused by fire and other perils Landlord elects to cover,
including, without limitation, coverage for earthquakes and floods, (b)
commercial general liability insurance for the benefit of Landlord and its
designees and (c) such other coverage required by any lender or which Landlord
elects to obtain for the Premises, Building or Common Areas of the Complex,
including, without limitation, coverage for environmental liability and losses.
Notwithstanding anything to the contrary, Landlord reserves the right to adjust
the Base Insurance Costs if such Base Insurance costs including coverage's for
perils not required or elected to be insured by Landlord in the future.

                                       23
<PAGE>

                                                       Bayshore Corporate Center

                                   EXHIBIT C
                                   ---------

                             RULES AND REGULATIONS                   INITIAL
                                                                     STAMP

 1. No sign, placard, picture, advertisement, name or notice shall be inscribed,
displayed or printed or affixed to any part of the outside or inside of the
Building/Office Complex or the leased premises without the prior written consent
of Landlord and Landlord shall have the right to remove any such sign, placard,
picture, advertisement, name or notice without notice to and at the expense of
Tenant.
         All approved signs or lettering on doors shall be printed, painted,
affixed or inscribed at the expense of Tenant by a person approved of by
Landlord.
         Tenant shall not place anything or allow anything to be placed near the
glass of any window, door, partition or wall which may appear unsightly from
outside the leased premises; provided, however, that Landlord may furnish and
install a Building standard window covering at all exterior windows. Tenant
shall not without prior written consent of Landlord cover or otherwise sunscreen
any window.
2.  Landlord shall approve in writing, prior to installation, the method of
attachment of any objects affixed to walls, ceilings or doors.
3.  The bulletin board or directory of the Building/Office Complex will be
provided exclusively for the display of the name and location of Tenant only and
Landlord reserves the right to exclude any other names therefrom.
4.  The sidewalks, halls, passages, exits, entrances, elevators and stairways
shall not be obstructed by Tenant or used by Tenant for any purpose other than
ingress and egress from the leased premises. The halls, passages, exits,
entrances, elevators, stairways, balconies and roof are not for the use of the
general public and the Landlord shall in all cases retain the right to control
and prevent access thereto by all persons whose presence in the judgment of the
Landlord shall be prejudicial to the safety, character, reputation and interests
of the Building/Office Complex and its Tenants, provided that nothing herein
contained shall be construed to prevent such access to persons with whom the
Tenant normally deals in the ordinary course of Tenant's business unless such
persons are engaged in illegal activities. No Tenant and no employees or
invitees of any Tenant shall go upon the roof of the Building/Office Complex.
5.  Locks-No additional locks or bolts of any kind shall be placed upon any of
the doors or windows by Tenant, nor shall any changes be made in existing locks
or the mechanisms thereof without the prior written consent of the Landlord.
Tenant must, upon the termination of Tenant's tenancy, restore to Landlord all
keys of storage, offices and toilet rooms either furnished to or otherwise
procured by Tenant and in the event of the loss of any keys so furnished Tenant
shall pay to Landlord the costs thereof or of changing the lock or locks opened
by lost keys if Landlord deems it necessary to make a change.
6.  The toilet rooms, urinals, wash bowls and other apparatus shall not be used
for any purpose other than that for which they were constructed and no foreign
substance of any kind whatsoever shall be thrown therein and the expense of any
breakage, stoppage or damage resulting from the violation of this rule shall be
borne by the Tenant who, or whose employees or invitees, shall have caused it.
7.  Tenant shall not overload the floor of the leased premises or mark, drive
nails, screw or drill into the partitions, woodwork or plaster or in any way
deface the leased premises or any part thereof. No boring, cutting or stringing
of wires shall be permitted except with the prior written consent of the
Landlord and as the Landlord may direct.
8.  No furniture, freight or equipment of any kind shall be brought into the
Building/Office Complex without the consent of Landlord and all moving of the
same into or out of the Building/Office Complex shall be done at such time and
in such manner as Landlord shall designate. Landlord shall have the right to
prescribe the weight, size and position of all safes and other heavy equipment
brought into the Building/Office Complex and also the times and manner of moving
the same in and out of the Building/Office Complex. Safes or other heavy objects
shall, if considered necessary by Landlord, stand on wood strips of such
thickness as is necessary to properly distribute the weight. Landlord will not
be responsible for loss of or damage to any such safe or property from any cause
and all damage done to the Building/Office Complex by moving or maintaining any
such safe or other property shall be repaired at the expense of the Tenant.
There shall not be used in any space, or in the public halls of the
Building/Office Complex, either by any Tenant or others, any hand trucks except
those equipped with rubber tires and side guards.
9.  Janitorial Service-Tenant shall not employ any person or persons for the
purpose of cleaning the leased premises without the consent of Landlord.
Landlord shall be in no way responsible to Tenant for any loss of property from
the leased premises, however occurring, or for any damage done to the effects of
Tenant by the Janitorial Service or any of Landlord's employees, or by any other
person. Janitorial

                                      24.
<PAGE>

                                                       Bayshore Corporate Center

service will not include the cleaning of carpets and rugs, other than vacuuming.
Tenant shall not cause unnecessary labor by reason of Tenant's carelessness and
indifference in the preservation of good order and cleanliness.
10.   Tenant shall not use, keep or permit to be used any food or noxious gas or
substance in the leased premises, or permit or suffer the leased premises to be
occupied or used in a manner offensive or objectionable to the Landlord or other
occupants of the Building/Office Complex by reason of noise, odors, and/or
vibrations, or interfere in any way with other Tenants or those having business
therein nor shall any animals or birds be brought in or kept in or about the
leased premises or the BOC. No Tenant shall make or permit to be made any
unseemly or disturbing noises or disturb or interfere with occupants of this or
neighboring Buildings or leased premises or those having business with them
whether by the use of any musical instrument, radio, phonograph, unusual noise,
or in any other way. No Tenant shall throw anything out of door or down the
passageways. No trash shall be put in the common areas before 5:00 p.m.
11.   The leased premises shall not be used for manufacturing or for the storage
of merchandise except as such storage may be incidental to the use of the leased
premises for general office purposes. No Tenant shall occupy or permit any
portion of his leased premises for anything other than general office purposes.
No Tenant shall occupy or permit any portion of his leased premises to be
occupied as an office for the manufacture or sale of liquor, narcotics, or
tobacco in any form, or as a medical office, or as a barber shop or manicure
shop. The leased premises shall not be used for lodging or sleeping or for any
illegal purposes.
12.   Tenant shall not use or keep in the leased premises or the Building/Office
Complex any kerosene, gasoline, or inflammable or combustible fluid or material.
13.   Landlord will direct electricians as to where and how telephone and
telegraph wires are to be introduced. No boring or cutting for wires will be
allowed without the consent of Landlord. The location of telephones, call boxes
and other office equipment affixed to the leased premises shall be subject to
the approval of the Landlord.
14.   Installation of Floor Coverings-No Tenant shall lay linoleum or other
similar floor covering so that the same shall be affixed to the floor of the
leased premises in any manner except by a paste, or other material, which may
easily be removed with water, the use of cement or other similar adhesive
materials being expressly prohibited. The method of affixing any such linoleum
or other similar floor covering to the floor, as well as the method of affixing
carpets or rugs to the lease premises, shall be subject to approval by Landlord.
The expense of repairs any damage resulting from a violation of this rule shall
be borne by Tenant by whom, or by whose agents, employees, or visitors, the
damage shall have been caused.
15.   Carpet/Floor Protection-Tenant shall provide and use chair pad and carpet
protectors at all desk and furniture locations.
16.   No furniture, packaging supplies, equipment or merchandise will be
received in the Building/Office Complex or carried up or down in the elevators
except between such hours and in such elevators as shall be designated by
Landlord.
17.   On Saturdays, Sundays and legal holidays and on other days between the
hours of 7:00 p.m. and 7:00 a.m. the following day, access to the
Building/Office Complex, or the halls, corridors, elevators or stairways in the
Building/Office Complex or to the leased premises may be refused unless the
person seeking access is known to the person or employee of the Building/Office
Complex in charge and has a pass or is property identified. The Landlord shall
in no case be liable for damages for any error with regard to the admission to
or exclusion from the Building/Office Complex of any person. In case of
invasion, mob, riot, public excitement, or other commotion, the Landlord
reserves right to prevent access to the Building/Office Complex during the
continuance of the same by closing the doors or otherwise, for the safety of the
Tenants and protection of property in the Building/Office Complex. The Landlord
reserves the right to close and keep locked all entrance and exit doors of the
Building/Office Complex on Saturdays, Sundays and legal holidays and other days
between the hours of 7:00 p.m. and 7:00 a.m., and during such further hours as
Landlord may deem advisable for the adequate protection of said Building/Office
Complex and the property of its Tenants.
18.   All entrance doors in the leased premises shall be left locked when the
leased premises are not in use, and all doors opening to public corridors shall
be kept closed except for normal ingress and egress from the leased premises.
19.   Landlord reserves the right to exclude or expel from the Building/Office
Complex any person who, in the judgment of Landlord, is intoxicated or under the
influence of liquor or drugs, or who shall in any manner do any act in violation
of any of the rules and regulations of the Building/Office Complex.

                                      25.
<PAGE>

                                                       Bayshore Corporate Center

20.  Employees of Landlord shall not perform any work or do anything outside of
their regular duties unless under special instructions from the Landlord, and no
employee will admit any person (Tenant or otherwise) to any office without
specific instruction from the Landlord.
21.  No vending machine or machines of any description shall be installed,
maintained or operated upon the lease premises without the prior written consent
of the Landlord.
22.  Landlord shall have the right, exersiable without notice and without
liability to Tenant, to change the name and the street address of the
Building/Office Complex of which the leased premises are a part.
23.  Tenant agrees that it shall comply with all fire and security regulations
that may be issued from time to time by Landlord and Tenant also shall provide
Landlord with the name of a designated responsible employee to represent Tenant
in all matters pertaining to such fire or security regulations.
24.  Landlord  reserves the right by written notice to Tenant to rescind,  alter
or waive any rule or regulation at any time prescribed for the Building/Office
Complex and its Tenants.
25.  Tenant shall not disturb, solicit or canvass any occupant of the
Building/Office Complex and shall cooperate to prevent the same.
26.  Without the prior written consent of Landlord, Tenant shall not use the
name of the Building/Office Complex in connection with or in promoting or
advertising the business of the Tenant except as Tenants address.
27.  Landlord shall furnish reasonable amounts of heating and air conditioning
during the hours of 7:00 a.m. to 6:00 p.m., Monday through Friday. In the event
                                                                   ------------
Tenant requires heating and air conditioning during off hours. Saturdays,
-------------------------------------------------------------------------
Sundays or holidays, there will be a $10.00 per unit, per hour charge. Tenants
---------------------------------------------------------------------
off hours usage will be billed monthly. Landlord and Tenant shall mutually agree
upon an estimated usage prior to Lease commencement. Tenant will be billed
monthly on this estimated amount and any changes will be adjusted on the end of
the year.
28.  Energy Conservation Measures - Tenant shall abide by all energy
conservation measures employed by Landlord, including but not limited to
requirements that lights be extinguished upon leaving the leased premises and
that draperies by closed at times specified by Landlord. Tenant shall not use
any method of heating or air conditioning other than that supplied by Landlord.
29.  Equipment Defects - Tenant shall give Landlord prompt notice of any
accidents to or defects in the water pipes, gas pipes, electric lights and
fixtures, heating apparatus, or any other service equipment.
30.  Parking - Vehicles are to park in properly marked spaces only. Under no
circumstances are vehicles to (a) back in, (b) park in space reserved for other
Tenants, (c) park in driveways, (d) park in front of entrances the
Building/Office Complex, (e) park in unmarked areas, (f) park in loading zones,
(g) park in two or more spaces, (h) park for over 48 hours without registering
the vehicle, in writing, with the Landlord or (i) park in areas reserved the
handicapped. Landlord shall have the right to cause improperly parked cars to be
towed at the owners expense.

                                      26.
<PAGE>

                                                       Bayshore Corporate Center

                                   EXHIBIT D
                                   ---------

                                PHONE AGREEMENT

Tenant's phone service will be provided through Cornerstone Properties I, LLC as
a condition of the Lease under the below General Terms and Conditions.

The attached Letter of Agency is to be signed and returned with this lease.

GENERAL TERMS AND CONDITIONS

A.  SUBSCRIBER RESPONSIBILITY: Subscriber assumes the responsibility for all
usage of the service, for all fees, charges, and taxes thereof, and for all the
use and security of subscriber's services rendered prior to notification of
misuse of authorization codes.

B.  PAYMENT TERMS: Subscriber agrees to remit payment for all services provided,
including taxes as applicable, upon receipt of invoice. Cornerstone Properties
I, LLC reserves the right to interrupt service to subscriber for late payments
of fees, charges, and taxes. Should subscriber fail to pay its bills in a timely
manner as required by this agreement, Cornerstone Properties I, LLC has the
right to terminate subscriber's use of their service on two (2) days written
notice. Subscriber also agrees to reimburse Cornerstone Properties I, LLC for
all reasonable expenses including reasonable attorneys' fees for expenses to
Cornerstone Properties I, LLC in the collection of past due balances.

C.  MISCELLANEOUS:
        1. In no event shall Cornerstone Properties I, LLC be liable for any
special, consequential, punitive or incidental damages, including loss of use,
profit, revenue or goodwill. Cornerstone Properties I, LLC shall not be liable
for any failure of performance due to causes and/or circumstances beyond its
control, nor shall Cornerstone Properties I, LLC be liable for any act or
omission for any other company furnishing any portion of service to subscriber,
any equipment supplied to subscriber (i.e. T1.5 channel banks, etc.) by
Cornerstone Properties I, LLC or any other supplier of equipment to subscriber
(under warranty, service agreement, or otherwise), or any network service
contracted by subscriber or Cornerstone Properties I, LLC. Subscriber
acknowledges and understand that the applicable tariff rates are subject to
change.
        2. This writing is intended by the parties as a final expression of
their agreement and as a complete and exclusive statement for the terms thereof.
The parties shall not be bound by any agent's or employee's representation,
promise, or inducement not set forth in this agreement.
        3. Except as set forth in clause 2, this agreement shall remain in
effect until revoked in writing on ten (10) days notice.
        4. This agreement is not effective until it is approved and signed by
Cornerstone Properties I, LLC and shall be governed and controlled by the laws
of the State of California.
        5. Should any provision of this agreement be found to be void or
unenforceable, it shall not affect the viability or enforceability of the other
provisions.
        6. This agreement shall be binding on, and, inure to the benefits of the
parties successors, assigns, heirs and beneficiaries.
        7. If Subscriber leases telephones, the Subscriber will be responsible
for any physical damage or loss of telephones.
        8. There are no ongoing service or maintenance fees associated with this
service.

LANDLORD:                                        CORNERSTONE PROPERTIES I, LLC

Date:    8/5/99                                  By: /s/ Steve Kaufman
     ------------------                             ----------------------------
                                                 Name: Steve Kaufman

TENANT:                                          AVANTGO, INC.

Dated:   8/5/99                                  By: /s/ [ILLEGIBLE]^^
      -----------------                             --------------------
                                                 Name:  [ILLEGIBLE]^^

                                      27.
<PAGE>

                                                       Bayshore Corporate Center

                                   EXHIBIT E
                                   ---------

                            COMMENCEMENT MEMORANDUM

       With respect to that certain Lease between AVANTGO, INC., as Tenant, and
CORNERSTONE PROPERTIES I, LLC, A California Limited Liability Company, as
Landlord, dated August 2, 1999, (the "Lease"), please be advised that the
Commencement Date with respect to 3503 RSF of space located in Building 1700,
Suite 200, San Mateo, California 94402.

        1.The Commencement Date for the entire Premises covered by this Lease is
          August 1, 1999.
        2.The Expiration Date for the entire Premises covered by this Lease is
          March 31, 2002.

        IN WITNESS WHEREOF, this Notice of Commencement Date is executed this___
day of_______________, 19__________.

LANDLORD:                          CORNERSTONE PROPERTIES I, LLC

                                   By: /s/ Steve Kaufman
                                      -------------------------
                                   Name:   Steve Kaufman

TENANT:                            AVANTGO, INC.

                                   By: /s/ [ILLEGIBLE]
                                      --------------------------
                                   Name:   [ILLEGIBLE]

                                       28.<PAGE>

                                                                   EXHIBIT 10.55

                                   NET LEASE
                            BASIC LEASE INFORMATION

DATE:               March 31, 2000
                          --
LANDLORD:           The Multi-Employer Property Trust, a trust organized under
                    12 C.F.R. Section 9.18

TENANT:             AvantGo, Inc., a Delaware corporation

PREMISES:           The entire rentable area of the building located at 25901
                    Industrial Blvd., Hayward,California ("Building E"), and the
                    entire rentable area of the building located at 25881
                    Industrial Blvd., Hayward, California ("Building F"), each
                    as shown on Exhibit A attached hereto. Landlord and Tenant
                    stipulate that for all purposes of this Lease the Building E
                    Premises contains 36,932 rentable square feet and the
                    Building F Premises contains 51,449 rentable square feet.

PROPERTY:           Mt. Eden Business Park, Hayward, California

USE:                General office, administrative, light manufacturing and
                    warehousing purposes.

TERM:               Approximately seven (7) years

ESTIMATED COMMENCEMENT DATE:          August 1, 2000

INITIAL BASE RENT:                    $141,410.00 ($1.60 per rentable sq. ft.
                                      per month)

TENANT'S PERCENTAGE SHARE:            100% (Building E Premises)
                                      100% (Building F Premises)

SECURITY DEPOSIT:                     $3,250,000.00 Letter of Credit

BROKERS:     Colliers Parish International Inc. (representing Landlord)
             Cornish & Carey Commercial (representing Tenant)

ADDRESS FOR NOTICES:  Landlord:       The Multi-Employer Property Trust
                                      c/o Riggs & Company
                                      808 17th Street N.W.
                                      Washington, D.C. 20006
                                      Attn: Patrick O. Mayberry

                      Tenant:         AvantGo, Inc.
                                      1700 South Amphlett Blvd., Suite 300
                                      San Mateo, CA 94402

  After Commencement Date:            To Tenant at the Premises, Attn: Tom
                                      Hunter

LANDLORD'S CONTRIBUTION
TO TENANT IMPROVEMENTS:               $2,209,525.00

LANDLORD'S INITIALS:/s/[illegible]^   TENANT'S INITIAL'S:/s/[illegible]^
                   ----------------                      ----------------
<PAGE>

TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                         Page
                                                         ----
<S>                                                      <C>
   1.  Premises.                                            1
   2.  Term.                                                1
   3.  Rent                                                 2
   4.  Base Rent                                            3
   5.  Operating Expenses                                   3
   6.  Proration of Rent                                    6
   7.  Tenant Improvements                                  7
   8.  Use of the Premises                                  7
   9.  Alterations                                          9
  10.  Repairs                                             10
  11.  Damage or Destruction                               10
  12.  Eminent Domain                                      11
  13.  Indemnity and Insurance                             12
  14.  Assignment or Sublet                                14
  15.  Default                                             17
  16.  Landlord's Right to Perform Tenant's Covenants      18
  17.  Letter of Credit                                    19
  18.  Surrender of Premises                               20
  19.  Holding Over                                        21
  20.  Access to Premises                                  21
  21.  Signs                                               21
  22.  Subordination                                       22
  23.  Transfer of the Property                            23
  24.  Estoppel Certificates; Financial Statements         23
  25.  Mortgagee Protection                                23
  26.  Attorneys' Fees                                     24
  27.  Brokers                                             24
  28.  Parking                                             24
  29.  Utilities and Services                              24
  30.  Intentionally Deleted                               25
  31.  Acceptance                                          25
  32.  Use of Building Name                                25
  33.  Recording                                           25
  34.  Quitclaim                                           25
  35.  Notices                                             25
  36.  Landlord's Exculpation                              26
  37.  Additional Structures                               26
  38.  Consents and Approvals                              26
  39.  General                                             26
</TABLE>

EXHIBIT "A": Premises Designation
EXHIBIT "A-1": Property Site Plan
EXHIBIT "B": Tenant Improvements
EXHIBIT "C": Commencement Date Memorandum
EXHIBIT "D": Rules and Regulations
EXHIBIT "E": Form of Tenant Estoppel Certificate
<PAGE>

                                   NET LEASE

  THIS LEASE, which is effective as of the date set forth in the Basic Lease
Information, is entered by Landlord and Tenant, as set forth in the Basic Lease
Information. Terms which are capitalized in this Lease shall have the meanings
set forth in the Basic Lease Information or as otherwise defined in this Lease.

1.    Premises.
      --------

  Landlord leases to Tenant, and Tenant leases from Landlord, the Premises
described in the Basic Lease Information (as shown on Exhibit A), together with
                                                      ---------
the right in common to use the Common Areas. The Common Areas shall mean the
areas and facilities within the land shown on Exhibit A-1 (the "Land") and
within all buildings and improvements now or hereafter located on the Land, in
each case to the extent provided and designated by Landlord for the general use,
convenience or benefit of Tenant and other tenants and occupants of the Property
(e.g., restrooms; janitorial, telephone and electrical closets; sidewalks;
 ---
driveways, public lobbies, entrances and stairs; and unreserved parking areas).
So long as the entire rentable area of any building on the Land is contained in
the Premises, such building shall not have any Common Areas. The Common Areas
shall include the Cultural Center delineated on Exhibit A-1 (the "Cultural
                                                -----------
Center"); provided, however, that Landlord may from time to time prescribe rules
and regulations for use of and access to the Cultural Center by Tenant and other
tenants of the Property. Without limitation of the provisions of any such rules
and regulations, Tenant acknowledges that (i) no tenant of the Property
(including Tenant) shall have exclusive rights to use the Cultural Center, (ii)
some or all of the tenants of the Property (including Tenant) may be excluded
from use of the Cultural Center from time to time to accommodate use of the
Cultural Center for special events, (iii) access to the Cultural Center shall be
restricted by means of a locked gate or other apparatus after normal business
hours, as prescribed from time to time by Landlord. Landlord reserves the right
to make changes to the Common Areas. Building E and Building F are each referred
to herein as a "Building" and are collectively referred to herein as the
"Buildings". The Buildings and such other buildings and improvements now or
hereafter located on the Land, together with the Land and the Common Areas, are
collectively referred to in this Lease as the "Property" or the "Real Property".

2.    Term.
      ----

  a.  Lease Term. The term of this Lease (the "Term") shall commence on the
      ----------
Commencement Date (as defined in Subsection 2.b.) and, unless terminated on an
earlier date in accordance with the terms of this Lease, shall end on the date
(the "Expiration Date") that is the last day of the calendar month in which
occurs the seventh (7th) annual anniversary of the Commencement Date. Tenant
acknowledges that on the Commencement Date, the Term, and Tenant's obligation to
pay Base Rent and Operating Expenses pursuant to Sections 4 and 5, respectively,
shall commence as to the entire Premises, notwithstanding that the Tenant
Improvements in the Building E Premises shall not have been Substantially
Completed by such date and that Tenant is unable to use the Building E Premises
for the conduct of its business by such date.

  b.  Commencement Date. The "Commencement Date" of this Lease shall be the
      -----------------
earliest to occur of the following: (i) the date that the Tenant Improvements
(as defined in Exhibit B attached hereto) in the Building F Premises have been
               ---------
Substantially Completed and Landlord provides written notice thereof to Tenant;
(ii) the date Tenant occupies the Building F Premises or the Building E Premises
or any portion of either for the conduct of business; or (iii) the date the
Commencement Date would have occurred but for Tenant Delay. For all purposes of
this Lease, Tenant shall be deemed to have taken occupancy of the entire
Premises upon the Commencement Date.

  "Substantial Completion of the Tenant Improvements" shall be deemed to have
occurred when the Tenant

                                       1
<PAGE>

Improvements have been completed in accordance with the Final Plans (as defined
in Exhibit B), subject only to the completion or correction of Punch List Items.
   ---------
Tenant shall be responsible, at its sole cost and expense, for obtaining any
permits required by reason of Tenant's particular use of the Premises
(including, without limitation, permits for any Hazardous Materials used in
connection therewith) (collectively, the "Special Use Permits"), and in no event
shall Substantial Completion of the Tenant Improvements require that the Special
Use Permits have been obtained. "Punch List Items" shall mean incomplete or
defective work or materials in the Tenant Improvements which do not materially
impair Tenant's use of the Premises for the conduct of Tenant's business
therein. "Tenant Delay" means any delay in completion of the Tenant Improvements
caused or requested by Tenant, including any such delay caused by (I) any
Changes (as defined in Exhibit B attached hereto) to the Tenant Improvements
                       ---------
requested by Tenant (including any proposed Changes that are not ultimately
approved or made), (II) Tenant's interference with the construction of the
Tenant Improvements (including any early entry into the Premises, whether or not
approved by Landlord), (III) Tenant's failure to promptly respond to inquiries
regarding the construction of the Tenant Improvements or to promptly make any
selection of materials, finishes or colors, (IV) Tenant's failure to approve or
reasonably disapprove any plans or specifications or costs or budgets or other
items within the time period set forth on Exhibit B for the same, (V) Tenant's
                                          ---------
failure to furnish any information to Landlord within the time period set forth
on Exhibit B for the same, (VI) Tenant's request that the Tenant Improvements
   ---------
include special materials, finishes or installations or other so-called "long
lead" items, or (VII) the Special Use Permits, or any requirement that the same
be obtained.

  Landlord shall endeavor in good faith to notify Tenant in writing of any
Tenant Delay (identifying the nature of the Tenant Delay) as soon as reasonably
practicable after Landlord becomes actually aware of such Tenant Delay, together
with Landlord's then good faith estimate of the probable duration of such Tenant
Delay.

  c.   Premises Not Delivered. If, for any reason, the Commencement Date does
       ----------------------
not occur by the Estimated Commencement Date, the failure shall not affect the
validity of this Lease, or the obligations of Tenant under this Lease, and
Landlord shall not be subject to any liability. Notwithstanding the foregoing,
in the event that the Commencement Date does not occur by December 1, 2000, as
such date shall be extended for delays caused by Tenant Delay or Force Majeure
(such date, as so extended, the "Trigger Date"), then Tenant shall have the
right to terminate this Lease (as to all of the Premises only) by notice to
Landlord given, if at all, within ten (10) days after the Trigger Date. For
purposes of this Lease, "Force Majeure" shall mean strikes, lock-outs, labor
disputes, shortages of material or labor, fire, earthquake, flood or other
casualty, acts of God or any other cause (other than financial inability) beyond
the reasonable control of Landlord.

  d.   Commencement Date Memorandum. When the Commencement Date is determined,
       ----------------------------
the parties shall execute a Commencement Date Memorandum, in the form attached
hereto as Exhibit C, setting forth the Commencement Date and the Expiration
          ---------
Date.

  e.   Early Entry. If Tenant is permitted by Landlord to enter the Premises
       -----------
prior to the Commencement Date for the purpose of fixturing or any purpose other
than the conduct of Tenant's business, the entry shall be subject to all the
terms and provisions of this Lease, except that Tenant's obligation to pay Base
Rent and Operating Expenses shall not commence until the Commencement Date.
Without limitation, in no event will Landlord consent to such early access if
Landlord shall reasonably determine that the same might delay or interfere with
Landlord's construction of the Tenant Improvements, or increase the cost of the
Tenant Improvements.

3.     Rent.
       ----
                                       2
<PAGE>

  As used in this Lease, the term "Rent" shall include: (i) the Base Rent; (ii)
Operating Expenses payable by Tenant pursuant to Section 5 below; and (iii) all
other amounts which Tenant is obligated to pay under the terms of this Lease.
All amounts of money payable by Tenant to Landlord shall be paid without prior
notice or demand, deduction or offset. If any installment of Base Rent is not
paid by Tenant by the fifth (5th) day of the month, or if any payment of
Operating Expenses or any other amount payable by Tenant is not paid within five
(5) days of the due date thereof, Tenant shall pay to Landlord a late payment
charge equal to five percent (5%) of the amount of the delinquent amount, in
addition to the amount of Rent then owing, regardless of whether a notice of
default or notice of termination has been given by Landlord. In addition to the
five percent (5%) late charge, any Base Rent, Operating Expenses or other
amounts owing hereunder which are not paid within five (5) days after the date
they are due shall thereafter bear interest at the rate ("Interest Rate") which
is the lesser of eighteen percent (18%) per annum or the maximum rate permitted
by applicable law.

4.     Base Rent.
       ---------

  a.   Initial Base Rent. Commencing on the Commencement Date, and thereafter on
       -----------------
the first day of each calendar month of the Term, Tenant shall pay monthly base
rent ("Base Rent") for the entire Premises to Landlord (or other entity
designated by Landlord), in advance, at Landlord's address for notices (as set
forth in the Basic Lease Information) or at such other address as Landlord may
designate. The initial Base Rent shall be the amount set forth in the Basic
Lease Information. Base Rent payable hereunder for the first full calendar month
after Tenant's obligation to pay Base Rent commences shall be paid upon Tenant's
execution of this Lease.

  b.   Base Rent Adjustment. Effective as of each annual anniversary of the
       --------------------
Commencement Date, the Base Rent payable by Tenant for the Premises shall
increase to one-hundred four percent (104%) of the Base Rent then in effect for
the Premises (without taking into account any temporary rental abatements then
in effect).

5.     Operating Expenses.
       ------------------

  a.   Operating Expenses. Tenant shall pay Tenant's Percentage Share of
       ------------------
Operating Expenses incurred by Landlord during each calendar year falling in
whole or in part during the Term.

  b.   Operating Expenses. The term "Operating Expenses" shall include all
       ------------------
reasonable expenses and costs of every kind and nature, except as provided in
the next paragraph, which Landlord shall pay or become obligated to pay because
of or in connection with the ownership, management, administration, maintenance,
repair and operation of the Premises, the Buildings, the Common Areas, and the
balance of the Property, to the extent allocable, as reasonably determined by
Landlord, to the Buildings in which the Premises is located. Operating Expenses
shall include, without limitation, the following: (i) all impositions relating
to the Real Property, including Real Property Taxes (as defined in Section
5.d.); (ii) premiums for insurance relating to the Real Property, including as
set forth in Sections 13.b., 13.d. and 13.i., and insurance deductibles paid by
Landlord; (iii) wages, salaries, bonuses and expenses and benefits (including
hospitalization, medical, surgical, retirement plan, pension plan, union dues,
life insurance, including group life insurance, welfare and other fringe
benefits, and vacation, holidays and other paid absence benefits, and costs of
uniforms) of all on-site and off-site employees of Landlord or its agents, at
the rank of property manager or below, engaged in operation, management,
administration, maintenance, repair and security of the Real Property,
including, without limitation, administrative, management and accounting
personnel and the individual(s) responsible for management of the Property, and
payroll, social security, workers' compensation, unemployment and similar taxes
with respect to such employees of Landlord or its agents, and the cost of
providing disability or other benefits imposed by law or otherwise, with respect
to such

                                       3
<PAGE>

employees; (iv) costs of all supplies, materials and equipment rentals used in
operations; (v) all maintenance, janitorial, security and service costs; (vi) a
management fee not to exceed 5% of all gross revenues from the Real Property,
including revenues attributable to Tenant's and other tenants' payments of
Operating Expenses; (vii) legal and accounting expenses, including the cost of
audits by certified public accountants; (viii) all repair, painting and
maintenance costs relating to the Real Property and its Common Areas, including
sidewalks, landscaping, service areas, mechanical rooms, parking areas,
driveways and Building exteriors; (ix) all charges for heat, water, gas, steam,
fuel, electricity and other utilities used or consumed in the Buildings and
Common Areas; (x) costs of repairs, replacements, and general maintenance to and
of the Building Systems and the Base Building Components (as such terms are
defined in Sections 9.a. and 10.a.; respectively, below); (xi) the costs of
capital improvements, capital replacements, capital repairs, capital equipment,
and capital tools and devices installed or paid for by Landlord and intended to
reduce other Operating Expenses or required to comply with Legal Requirements
(as defined in Section 8.c. below) or intended for the protection of the health
and safety of the occupants of the Property; and (xii) Landlord's costs of
maintaining the Cultural Center, which costs shall be deemed, for purposes of
this Lease, the sum of $60,000.00, as such sum shall be increased on January 30,
1999 and each January 30th thereafter (each, an "Adjustment Date"), by the
percentage increase in the Index over the one (1) year period ending on the date
on which the Index is published in the month immediately preceding the
Adjustment Date. With respect to any costs included in Operating Expenses under
clause (x) which are capital expenditures, as determined by Landlord in
accordance with generally accepted accounting principles consistently applied,
and with respect to the costs of items included in Operating Expenses under
clause (xi), such costs shall be amortized over a period determined by Landlord,
together with interest on the unamortized balance at a rate per annum equal to
three (3) percentage points over the Treasury Rate charged at the time such item
is constructed or acquired, or at such higher rate as may have been paid by
Landlord on funds borrowed for the purpose of acquiring or constructing such
item, but in either case not more than the maximum rate permitted by law at the
time such item is acquired or constructed. As used herein, "Treasury Rate" means
the six-month United States treasury bill rate in effect from time to time by
the San Francisco Main Office of Bank of America, NA (or any successor bank
thereto), or if there is no such rate, the rate quoted by such bank in pricing
ninety day commercial loans to substantial commercial borrowers.

     The term "Index" as used herein shall mean the Consumer Price Index for All
Urban Consumers (1982-84 = 100) San Francisco-Oakland-San Jose, California, All
Items, published by the Bureau of Labor Statistics of the U.S. Department of
Labor. If the Bureau of Labor Statistics ceases to publish the above Index, or
if the above Index is otherwise renamed, discontinued or superseded, the parties
agree that the Bureau of Labor Statistics or any successor governmental agency
thereto will be the sole judge of the comparability of successive indexes, but
if no succeeding index is published, the calculations under this Lease based on
the Index shall be made using the most closely comparable statistics on the
purchasing power of the consumer dollar as published by a responsible financial
authority and selected by Landlord.

     Operating Expenses shall not include the following: (i) depreciation on the
Buildings or other buildings located on the Land, or equipment or systems
therein; (ii) debt service; (iii) rental under any ground or underlying lease;
(iv) attorneys' fees and expenses incurred in connection with lease negotiations
or disputes with past, current or prospective Building tenants; (v) the cost of
decorating, improving for tenant occupancy, painting or redecorating portions of
the Buildings or other buildings located on the Land to be demised to tenants;
(vi) advertising expenses; (vii) costs reimbursed by insurance proceeds; (viii)
real estate broker's or other leasing commissions; or (viii) costs allocable to
the Common Areas in any of the buildings on the Land in which no portion of the
Premises is located.

     The parties agree that statements in this Lease to the effect that Landlord
is to perform certain of its obligations hereunder at its own or sole cost
and/or expense shall not be interpreted as excluding any cost from Operating
Expenses if such cost is an Operating Expense pursuant to the terms of this
Section 5.b.

                                       4
<PAGE>

  c.   Monthly Increments; Adjustment. Promptly following the commencement of
       ------------------------------
the Term and prior to the commencement of each subsequent calendar year (or as
soon thereafter as practicable), Landlord shall estimate the Operating Expenses
payable by Tenant for such calendar year pursuant to this Section. Tenant shall
pay to Landlord, on the first day of each month, in advance, one-twelfth (1/12)
of Landlord's estimated amount. If at any time during the course of the year
Landlord determines that the Operating Expenses payable by Tenant will vary from
the then estimated amount, by notice to Tenant Landlord may revise the amount
payable by Tenant during the balance of the calendar year such that the total
estimated additional amount due from Tenant for such calendar year is paid by
Tenant during the balance of the calendar year in equal monthly amounts. Within
ninety (90) days (or as soon thereafter as practicable) after the close of each
calendar year, Landlord shall provide Tenant with a statement to account for any
difference between the actual and the estimated Operating Expenses for the
previous year. Landlord's annual statement shall be final and binding upon
Landlord and Tenant unless, within ninety (90) days after delivery thereof to
Tenant, Landlord shall revise or Tenant shall contest any item therein by
written notice to the other, specifying each item revised or contested and the
reason therefor. Notwithstanding the foregoing, the Real Property Taxes included
in any such annual statement may be modified by any subsequent adjustment or
retroactive application of Real Property Taxes affecting the calculation of
Operating Expenses. If Tenant has overpaid the amount of Operating Expenses
owing pursuant to this Section, Landlord shall credit the overpayment against
Tenant's next payments due under this Section 5. If Tenant has underpaid the
amount of Operating Expenses owing pursuant to this Section, Tenant shall pay
the amount of the underpayment to Landlord within thirty (30) days after
Tenant's receipt of Landlord's statement. If the rentable area of either
Building is not fully occupied during any calendar year, Operating Expenses for
such calendar year for such Building shall be adjusted to equal Landlord's
reasonable estimate of the Operating Expenses which would have been incurred
during such calendar year if the total rentable area of such Building were
occupied.

  d.  Definition of Real Property Taxes. The term "Real Property Taxes" shall
      ---------------------------------
mean any ordinary or extraordinary form of assessment or special assessment,
license fee, rent tax, levy, penalty (if a result of Tenant's delinquency), or
tax (other than net income, estate, succession, inheritance, transfer or
franchise taxes), imposed by any authority having the direct or indirect power
to tax, or by any city, county, state or federal government for any maintenance
or improvement or other district or division thereof. The term shall include all
transit charges, housing fund assessments, real estate taxes and all other taxes
relating to the Premises, Buildings and/or Property, all other taxes which may
be levied in lieu of real estate taxes, all assessments, assessment bonds,
levies, fees, and other governmental charges (including, but not limited to,
charges for traffic facilities, improvements, child care, water services studies
and improvements, and fire services studies and improvements) for amounts
necessary to be expended because of governmental orders, whether general or
special, ordinary or extraordinary, unforeseen as well as foreseen, of any kind
and nature for public improvement, services, benefits or any other purposes
which are assessed, levied, confirmed imposed or become a lien upon the
Premises, Buildings or Property or become payable during the Term.

  e.   Acknowledgment of Parties. It is acknowledged by Landlord and Tenant that
       -------------------------
Proposition 13 was adopted by the voters of the State of California in the June,
1978 election, and that assessments, taxes, fees, levies and charges may be
imposed by governmental agencies for such purposes as fire protection, street,
sidewalk, road, utility construction and maintenance, refuse removal and for
other governmental services which formerly may have been provided without charge
to property owners or occupants. It is the intention of the parties that all new
and increased assessments, taxes, fees, levies and charges due to Proposition 13
or any other cause are to be included within the definition of Real Property
Taxes for purposes of this Lease.

  f.   Taxes on Tenant Improvements and Personal Property. Notwithstanding any
       --------------------------------------------------
other provision hereof, Tenant shall pay the full amount of any increase in Real
Property Taxes during the Term resulting from any and all Alterations (as
defined in Section 9.a. below) of any kind whatsoever placed in, on or about

                                       5
<PAGE>

the Premises for the benefit of, at the request of, or by Tenant. Tenant shall
pay, prior to delinquency, all taxes assessed or levied against Tenant's
personal property, equipment, furniture or fixtures (collectively, "Personal
Property") in, on or about the Premises. When possible, Tenant shall cause its
Personal Property to be assessed and billed separately from the real or personal
property of Landlord. Tenant recognizes that pursuant to Section 107.6 of the
California Revenue and Taxation Code Tenant's possessory interest under this
Lease may be subject to property taxation based on the full cash value, as
defined in Sections 110 and 110.1 of the California Revenue and Taxation Code.

  g.   Fiscal Year. Landlord shall have the right to account and bill for
       -----------
Operating Expenses on the basis of a fiscal year, rather than a calendar year as
set forth above, and to revise such fiscal year from time to time, provided that
Landlord follows generally accepted accounting principles consistently applied
in connection therewith.

  h.   Net Lease. This shall be a Net Lease and Base Rent shall be paid to
       ---------
Landlord absolutely net of all costs and expenses except as expressly herein
provided. The provisions for Tenant's payment of Tenant's Percentage Share of
Operating Expenses are intended to pass on to Tenant and reimburse Landlord for
Tenant's Percentage Share of all costs and expenses associated with the Real
Property, except as expressly provided in this Lease.

  i.   Tenant's Audit Right. Tenant shall have the right to cause a reputable
       --------------------
nationally recognized accounting firm to audit Landlord's books and records
pertaining to Operating Expenses for the immediately prior calendar year,
provided that Tenant notifies Landlord in writing of Tenant's intention to
exercise such audit right within ninety (90) days after receipt of the relevant
annual statement described in Section 5.c., actually begins such audit within
thirty (30) days after such notice from Tenant (but in no event earlier than ten
(10) Business Days (as defined below) after such notice) and diligently pursues
such audit to completion. Landlord agrees to make available to Tenant's
auditors, at the Buildings or at Landlord's office in the State of California,
the books and records relevant to the audit for review and copying, but such
books and records may not be removed from Landlord's location. Tenant shall
promptly deliver to Landlord a copy of the report or other documentation
prepared by Tenant's auditors upon completion of the audit. Tenant shall bear
all costs of such audit, except that, if the audit (as conducted and certified
by Tenant's nationally recognized accounting firm) shows an aggregate
overstatement of Operating Expenses of more than five percent (5%), and
Landlord's auditors concur in such findings (or, in the absence of such
concurrence, such overstatement is ultimately confirmed by dispute resolution),
then Landlord shall bear Tenant's costs of the audit, such payment to be made by
Landlord within thirty (30) days of Landlord's receipt of the invoice (with
reasonably satisfactory supporting documentation) for such costs. If the agreed
or confirmed audit shows an underpayment of Operating Expenses by Tenant, Tenant
shall pay to Landlord, within thirty (30) days after the audit is agreed to or
confirmed, the amount owed to Landlord, and, if the agreed or confirmed audit
shows an overpayment of Operating Expenses by Tenant, Landlord shall reimburse
Tenant for such overpayment within thirty (30) days after the audit is agreed to
or confirmed. As used in this Lease, a "Business Day" is Monday through Friday,
excluding state or federal holidays.

6.   Proration of Rent. If the Commencement Date is not the first day of a
     -----------------
calendar month, or if the end of the Term is not the last day of a calendar
month, Base Rent payable by Tenant pursuant to Section 4, and Operating Expenses
payable by Tenant pursuant to Section 5, shall be prorated on a daily basis
(based upon a thirty (30) day month) for such fractional month. If any date on
which Base Rent is to be adjusted hereunder is not the first day of a calendar
month, Base Rent payable by Tenant pursuant to Section 4 for such calendar month
shall be prorated on a daily basis (based on the number of days in such month)
to take into account the differing Base Rent rates. The termination of this
Lease shall not affect the obligations of Landlord and Tenant pursuant to
Section 5.c. which are to be performed after the termination.

                                       6
<PAGE>

7.     Tenant improvements.   Landlord agrees to construct within the Premises
       -------------------
certain improvements to the Premises ("Tenant Improvements") pursuant to the
terms of Exhibit B. Subject to completion of the Tenant Improvements, if any,
         ---------
and to Landlord's obligations set forth below in this Section 7, the Premises
shall be delivered to Tenant in its then "as-is" condition, and Landlord shall
not have any obligation to make or pay for any alterations, additions,
improvements or repairs to prepare the Premises for Tenant's occupancy. The
foregoing is not intended to diminish Landlord's repair and maintenance
obligations pursuant to other provisions of this Lease. Within fifteen (15) days
after Substantial Completion of the Tenant Improvements, but prior to Tenant
moving any of its furniture, fixtures or equipment into the Premises, upon
either party's request Landlord and Tenant shall together conduct an inspection
of the Premises and prepare a list of the Punch List Items any items of the
Tenant Improvements that are not in conformity with the Tenant Improvements as
required by the terms of this Lease. Landlord shall use its good faith efforts
to correct all such items within a reasonable period of time following
preparation of such list. In addition, within thirty (30) days following
preparation of such list, upon either party's request Landlord and Tenant shall
conduct a second inspection of the Premises and prepare a second list with
respect to any items that were not adequately completed from the first list and
any items that were not reasonably discoverable during the first inspection.
Landlord shall use its good faith efforts to correct any items listed on the
second list within a reasonable period of time following preparation of such
list. During the term of this Lease, Landlord shall use its good faith efforts
to enforce any warranty claims with respect to the construction of the Tenant
Improvements.

8.     Use of the Premises.
       -------------------

  a.   Use. The Premises shall be used solely for the use set forth in the Basic
       ---
Lease Information and for no other use or purpose. Tenant shall not do or suffer
or permit anything to be done in or about the Premises or the Real Property
which will in any way obstruct or interfere with the rights of other tenants or
occupants of the Buildings or injure or annoy them, or use or suffer or permit
the Premises to be used for any immoral, unlawful or objectionable purpose, nor
shall Tenant cause, maintain, suffer or permit any nuisance in, on or about the
Premises or the Real Property. Without limiting the foregoing, Tenant shall not
permit any odors, smoke, dust, gas, substances, noise or vibration to emanate
from the Premises, and no loudspeakers or other similar device which can be
heard outside the Premises shall, without the prior written approval of
Landlord, be used in or about the Premises. Tenant shall not commit or suffer to
be committed any waste in, to or about the Premises. Tenant agrees not to employ
any person, entity or contractor for any Alterations in the Premises or for
moving Tenant's equipment and furnishings in, out or around the Premises whose
presence may give rise to a labor or other disturbance in a Building or the
balance of the Property and, if necessary to prevent such a disturbance in a
particular situation, Landlord may require Tenant to employ union labor for the
work.

  b.   Rules and Regulations; CC&R's. Tenant shall comply with the Rules and
       -----------------------------
Regulations attached hereto as Exhibit D, as the same may be modified from time
                               ---------
to time by Landlord upon prior notice to Tenant (the "Rules"). In addition,
Tenant shall comply with any covenants, conditions and restrictions ("CC&R's")
applicable to the Real Property, and all rules, regulations and restrictions
imposed by any association formed pursuant to the CC&R's, in each case to the
extent Landlord has delivered a copy thereof to Tenant and the same are not in
conflict with the provisions of this Lease.

  c.   Compliance. Tenant shall not permit the Premises to be used in violation
       ----------
of or in conflict with, and at its sole cost and expense shall promptly comply
with, all laws, statutes, ordinances and governmental rules, regulations or
requirements now in force or which hereinafter may be in force, with the
requirements of any board of fire underwriters or other similar board now or
hereafter constituted, with any direction or occupancy certificate issued
pursuant to any law by any public officer or officers, as well as the provisions
of all recorded documents affecting the Premises (all of the foregoing,
collectively, "Legal Requirements"),

                                       7
<PAGE>

insofar as any thereof relate to or affect the condition, use or occupancy of
the Premises, and Tenant shall perform all work to the Premises and other
portions of the Real Property required to effect such compliance (or, at
Landlord's election, Landlord may perform such work at Tenant's expense).
Notwithstanding the foregoing, Tenant's foregoing compliance obligations shall
not include any obligations necessitated by Landlord's failure to complete the
Tenant Improvements in accordance with all applicable Legal Requirements or by
the failure of the Base Building Components to be in compliance with all
applicable Legal Requirements as of the Commencement Date. The judgement of any
court of competent jurisdiction or the admission of Tenant in any actions
against Tenant, whether Landlord be a party thereto or not, that Tenant has so
violated any such law, statute, ordinance, rule, regulation or requirement,
shall be conclusive of such violation as between Landlord or Tenant.

  d.   Hazardous Materials. Tenant shall not cause or permit the storage, use,
       -------------------
generation, release, handling or disposal (collectively, "Handling") of any
Hazardous Materials (as defined below), in, on, or about the Premises or the
Real Property by Tenant or any agents, employees, contractors, licensees,
subtenants, customers, guests or invitees of Tenant (collectively with Tenant,
"Tenant Parties"), except that Tenant shall be permitted to use in the Premises
in a normal and customary manner normal quantities of office supplies or
products (such as copier fluids or cleaning supplies) customarily used in the
conduct of general business office activities ("Common Office Chemicals"),
provided that the Handling of such Common Office Chemicals shall comply at all
times with all Legal Requirements, including Hazardous Materials Laws (as
defined below). Upon Landlord's request from time to time, Tenant shall provide
to Landlord a complete written inventory of all Hazardous Materials which Tenant
anticipates using or storing on, or discharging from, the Premises along with
copies of all reports, permits and business plans filed with any federal, state,
local or other governmental agency. Tenant shall update the inventory as
frequently as required to reflect any material changes to the items required to
be disclosed therein. Tenant shall be solely responsible for and shall
indemnify, defend and hold Landlord and all other Indemnitees (as defined in
Section 13.a. below), harmless from and against all Claims (as defined in
Section 13.a. below), arising out of or in connection with, or otherwise
relating to (i) any Handling of Hazardous Materials by any Tenant Party or
Tenant's breach of its obligations hereunder, or (ii) any removal, cleanup, or
restoration work and materials necessary to return the Real Property or any
other property of whatever nature located on the Real Property to their
condition existing prior to the Handling of Hazardous Materials in, on or about
the Premises by any Tenant Party. Tenant's foregoing indemnity shall not apply
to the extent of Claims arising solely by reason of Hazardous Materials
conditions existing upon the Premises or the Real Property as of the date of
this Lease. Tenant shall promptly provide Landlord with copies of all notices
received by it, including, without limitation, any notice of violations, notice
of responsibility or demand for action from any federal, state or local
authority or official in connection with the presence of Hazardous Materials in
or about the Premises or any other portion of the Property. In the event of any
release of Hazardous Materials upon the Premises or any other portion of the
Property, or upon adjacent lands, if caused by Tenant or any other Tenant Party,
Tenant shall promptly remedy the problem in accordance with all applicable Legal
Requirements. For purposes of this Lease, "Hazardous Materials" means any
explosive, radioactive materials, hazardous wastes, or hazardous substances,
including without limitation asbestos containing materials, PCB's, CFC's, or
substances defined as "hazardous substances" in the Comprehensive Environmental
Response, Compensation and Liability Act of 1980, as amended, 42 U.S.C. Section
9601-9657; the Hazardous Materials Transportation Act of 1975, 49 U.S.C. Section
1801-1812; the Resource Conservation and Recovery Act of 1976, 42 U.S.C. Section
6901-6987; or any other Legal Requirement regulating, relating to, or imposing
liability or standards of conduct concerning any such materials or substances
now or at any time hereafter in effect (collectively, "Hazardous Materials
Laws"). Tenant's obligations under this Section 8.d. shall survive the
expiration or other termination of this Lease.

  e.   Quiet Enjoyment. If, and so long as, Tenant pays the Rent and keeps,
       ---------------
observes and performs each and every term, covenant and condition of this Lease
on the part or on behalf of Tenant to be kept, observed

                                       8
<PAGE>

and performed, Tenant shall peaceably and quietly enjoy the Premises throughout
the Term without hindrance by Landlord or any person lawfully claiming through
or under Landlord, subject to the provisions of this Lease (including, without
limitation, the provisions of Section 22 below and the prior rights of Ground
Lessors and Holders).

9.     Alterations.
       -----------

  a.   Alterations. Tenant shall not make any alteration, addition or
       -----------
improvement in, to or upon the Premises ("Alteration") without the prior written
consent of Landlord in each instance, which consent shall not be unreasonably
withheld with respect to proposed Alterations which (i) are not structural in
nature, (ii) do not affect the Base Building Components, (iii) are, in
Landlord's opinion, compatible with the Building and the balance of the Real
Property and the Building's mechanical, plumbing, electrical,
heating/ventilation/air conditioning, communication, security and fire and other
life safety systems (collectively, the "Building Systems"), and (iv) in
Landlord's opinion will not interfere with the use and occupancy of any other
portion of the Building or the Real Property by any other tenant or permitted
occupant thereof. Tenant shall give Landlord not less than ten (10) days' prior
written notice of any Alteration Tenant desires to make. Any Alterations as to
which Landlord shall consent shall be made only by contractors approved in
advance, in writing by Landlord, which approval shall not be unreasonably
withheld; provided, however, that Landlord may, in its sole discretion, specify
the engineers and contractors to perform any work relating to or affecting the
Building Systems or the Base Building Components. Tenant shall comply with all
Legal Requirements applicable to each Alteration and shall deliver to Landlord a
complete set of "as built" plans and specifications for each Alteration. Any
work to the balance of the Building or Real Property related to or affected or
triggered by Tenant's Alterations shall be performed by Tenant at Tenant's
expense (or, at Landlord's election, Landlord may perform such work at Tenant's
expense). Tenant shall be solely responsible for maintenance and repair of all
Alterations made by Tenant. Tenant shall pay Landlord on demand (whether prior
to or during the course of construction) an amount (the "Alteration Fee") equal
to five percent (5%) of the total cost of each Alteration (and for purposes of
calculating the Alteration Fee, such cost shall include architectural and
engineering fees, but shall not include permit fees) as compensation to Landlord
for miscellaneous costs incurred by Landlord in connection with the Alteration.
In addition, Tenant shall reimburse Landlord for all third party fees paid by
Landlord in connection with reviewing the proposed Alterations (whether or not
the proposed Alterations are ultimately approved by Landlord or made by Tenant),
including, without limitation, Landlord's architectural and engineering fees.
All Alterations shall be performed diligently and in a first-class workmanlike
manner and in accordance with plans and specifications approved by Landlord, and
shall comply with Landlord's construction procedures and requirements for the
Building (including Landlord's reasonable requirements relating to insurance and
contractor qualifications and scheduling of the work).

  b.   Liens. If, because of any act or omission of Tenant or anyone claiming
       -----
by, through, or under Tenant, any mechanic's lien or other lien is filed against
the Premises or any other portion of the Real Property or against other property
of Landlord (whether or not the lien is valid or enforceable), Tenant shall, at
its own expense, cause it to be discharged of record within a reasonable time,
not to exceed twenty (20) days, after the date of the filing. In addition,
Tenant shall defend and indemnify Landlord and hold it harmless from any and all
Claims resulting from the lien. Without limitation of Landlord's other remedies,
Landlord shall have the rights under Section 16 below if any such lien is not
timely discharged by Tenant.

  c.   Ownership of Alterations. All Alterations shall immediately become
       ------------------------
Landlord's property. Except as provided in Section 9.d., Landlord may require
Tenant, at Tenant's sole expense and by the end of the Term, to remove any
Alterations and to restore the Premises to its condition prior to the
Alteration.

  d.   Request Regarding Removal Obligation. At the time that Tenant requests
       ------------------------------------
Landlord's consent to

                                       9
<PAGE>

any Alteration, Tenant may request that Landlord notify Tenant if Landlord will
require Tenant, at Tenant's sole expense, to remove any or all of the Alteration
by the end of the Term, and to restore the Premises to its condition prior to
the Alteration. Unless Landlord shall have expressly agreed in writing not to
require such removal and restoration, Landlord's election right under Section
9.c. shall continue through the end of the Term as to such Alterations.
Notwithstanding the foregoing, except for the Above Standard Tenant Improvements
(as defined in Section 13.b.), Tenant shall have no obligation to remove the
Tenant Improvements constructed by Landlord pursuant to Exhibit B attached
hereto.

  10.    Repairs.
         -------

  a. Landlord's Repairs. Landlord shall maintain the roof, foundations, floor
     ------------------
slabs and exterior walls of the Buildings (collectively, the "Base Building
Components") in good condition and repair, reasonable wear and tear excepted.
The term walls as used herein shall not include windows, glass or plate glass,
doors, special store fronts or office entries. The term roof as used herein
shall not include skylights, smoke hatches or roof vents. Landlord shall also
maintain in good condition and repair, reasonable wear and tear excepted, the
Common Areas, including, but not limited to, the landscaped areas, parking areas
and driveways. Tenant shall reimburse Landlord for Landlord's costs of complying
with its obligations under this Section 10 in accordance with Section 5 above,
provided, however, that any damage caused by or repairs necessitated by any act
of Tenant or any other Tenant Party may be repaired by Landlord at Landlord's
option and at Tenant's expense. Tenant shall give Landlord prompt written notice
of any repairs required of Landlord pursuant to this Section 10, after which
notice Landlord shall have reasonable opportunity to perform the same. In
addition to the foregoing, Landlord shall, at Tenant's direct expense (and not
as an Operating Expense), enter into a regularly scheduled preventive
maintenance/service contract with a maintenance contractor for servicing all hot
water, heating and air conditioning systems and equipment within or serving the
Premises, and Tenant shall reimburse Landlord for all such expenses within
thirty (30) days after Landlord's demand.

  b.   Tenant's Repairs. Tenant shall, at Tenant's expense, maintain all parts
       ----------------
of the Premises in a good, clean and secure condition, promptly making all
necessary repairs and replacements including, but not limited to, all windows,
glass or plate glass, doors and any special store fronts or office entries,
walls and wall finishes, floor covering, Building Systems, truck doors, dock
bumpers, dock plates and levelers, plumbing work and fixtures, downspouts,
skylights, smoke hatches, roof vents and utility equipment, in each case to the
extent the same are located within or exclusively serve the Premises. Tenant
shall, at Tenant's expense, also perform necessary pest extermination and
regular removal of trash and debris. If required by the railroad company, Tenant
agrees to sign a joint maintenance agreement governing the use of the rail spur,
if any, located on the Real Property. Tenant shall not damage any demising wall
or disturb the integrity and support provided by any demising wall and shall, at
its sole expense, immediately repair any damage to any demising wall caused by
Tenant or its employees, agents or invitees or any other Tenant Party. Tenant
hereby waives all right to make repairs at the expense of Landlord or in lieu
thereof to vacate the Premises and its other similar rights as provided in
California Civil Code Sections 1932(1), 1941 and 1942 or any other Legal
Requirement (whether now or hereafter in effect).

11.    Damage or Destruction.
       ---------------------

  a.   Landlord's Obligation to Rebuild. If the Premises are damaged or
       --------------------------------
destroyed, Landlord shall promptly and diligently repair the Premises unless
Landlord has the option to terminate this Lease as provided herein, and Landlord
elects to terminate.

  b.   Right to Terminate. Landlord shall have the option to terminate this
       ------------------
Lease if the Premises or the Building is destroyed or damaged by fire or other
casualty, regardless of whether the casualty is insured

                                      10
<PAGE>

against under this Lease, if Landlord reasonably estimates that the repair of
the Premises or the Building cannot be completed within one hundred eighty (180)
days after the casualty. Landlord shall also have the right to terminate this
Lease if the repair is not fully covered by insurance maintained (or required to
be maintained) by the Landlord pursuant to this Lease other than by reason of
the deductible amounts under Landlord's insurance policies. Tenant shall have
the option to terminate this Lease if the Premises is damaged or destroyed by
fire or other casualty, and Landlord reasonably estimates that the repair of the
Premises cannot be completed within one hundred eighty (180) days after the
casualty. Landlord shall notify Tenant of Landlord's reasonable repair period
estimate within (60) days after the casualty. If a party desires to exercise the
fight to terminate this Lease as a result of a casualty, the party shall
exercise the right by giving the other party written notice of its election to
terminate within thirty (30) days after delivery of Landlord's repair period
estimate, in which event this Lease shall terminate fifteen (15) days after the
date of the terminating party's notice. If neither Landlord nor Tenant exercises
the right to terminate this Lease, this Lease shall continue in full force and
effect and Landlord shall promptly commence the process of obtaining necessary
permits and approvals, and shall commence repair of the Premises or the Building
as soon as practicable and thereafter prosecute the repair diligently to
completion.

  c.   Limited Obligation to Repair. Landlord's obligation, should Landlord
       ----------------------------
elect or be obligated to repair or rebuild, shall be limited to the Base
Building Components and any Tenant Improvements (including building systems) in
the Premises which are constructed and paid for by Landlord pursuant to Exhibit
                                                                        -------
B (other than the Above Standard Tenant Improvements). Tenant, at its option and
-
expense, shall replace or fully repair all trade fixtures, equipment,
Alterations and other improvements installed by Tenant and existing at the time
of the damage or destruction.

  d.   Abatement of Rent. In the event of any damage or destruction to the
       -----------------
Premises which does not result in termination of this Lease, the Base Rent and
Operating Expenses payable by Tenant shall be temporarily abated proportionately
to the degree the Premises are untenantable as a result of the damage or
destruction, commencing from the date of the damage or destruction and
continuing during the period required by Landlord to substantially complete its
repair and restoration of the Premises; provided, however, that nothing herein
shall preclude Landlord from being entitled to collect the full amount of any
rent loss insurance proceeds. Tenant shall not be entitled to any compensation
or damages from Landlord for loss of the use of the Premises, damage to Tenant's
Personal Property or any inconvenience occasioned by any damage, repair or
restoration. Tenant hereby waives the provisions of Section 1932, Subdivision 2,
and Section 1933, Subdivision 4, and Sections 1941 and 1942 of the California
Civil Code, and the provisions of any similar Legal Requirement (whether now or
hereafter in effect).

  e.   Insurance Proceeds. If this Lease is terminated, Landlord may keep all
       ------------------
the insurance proceeds resulting from the damage payable pursuant to insurance
coverage maintained by Landlord, and Tenant shall have no claims thereto.

  f.   Separate Buildings. In recognition that the Premises are located in two
       ------------------
separate Buildings, the provisions of this Section 11 shall be applied
separately as to each such Building and the portion of the Premises located
therein.

12.    Eminent Domain. If all or any material part of the Premises or balance of
       --------------
the Real Property is taken for public or quasi-public use by a governmental
authority under the power of eminent domain or is conveyed to a governmental
authority in lieu of such taking (a "taking"), Landlord may terminate this Lease
by written notice to Tenant within thirty (30) days after the taking. If all or
any material part of the Premises is taken, and if the taking causes the
remaining part of the Premises to be untenantable and inadequate for use by
Tenant for the purpose for which they were leased, then Tenant, at its option
and by giving notice within thirty (30) days after the taking, may terminate
this Lease as of the date Tenant is

                                      11
<PAGE>

required to surrender possession of the Premises. If part of the Premises is
taken but the remaining part is tenantable and adequate for Tenant's use, then
this Lease shall be terminated as to the part taken as of the date Tenant is
required to surrender possession, and, unless Landlord shall have terminated
this Lease pursuant to the foregoing provisions, Landlord shall make such
repairs, alterations and improvements as may be necessary to render the part not
taken tenantable, and the Base Rent and Operating Expenses payable by Tenant
shall be reduced in proportion to the part of the Premises taken. All
compensation awarded for the taking shall be the property of Landlord without
any deduction therefrom for any estate of Tenant, and Tenant hereby assigns to
Landlord all its right, title and interest in and to the award. Tenant shall
have the right, however, to recover from the governmental authority, but not
from Landlord, such compensation as may be awarded to Tenant on account of the
interruption of Tenant's business, moving and relocation expenses and removal of
Tenant's Personal Property, provided that any such award to Tenant will not
reduce the award which would otherwise be made to Landlord. In recognition that
the Premises are located in two separate Buildings, the provisions of this
Section 12 shall be applied separately as to each such Building and the portion
of the Premises located therein.

13.    Indemnity and Insurance.
       -----------------------

  a.   Indemnity. Tenant shall hold Landlord and its constituent shareholders,
       ---------
partners, members or other owners, and all of their agents, contractors,
servants, officers, directors, employees and licensees (collectively with
Landlord, the "Indemnitees") harmless from and indemnify the Indemnitees against
any and all claims, liabilities, damages, costs and expenses, including
reasonable attorneys' fees and costs incurred in defending against the same
(collectively, "Claims"), to the extent arising from (a) the acts or omissions
of Tenant or any other Tenant Party in, on or about the Real Property, or (b)
any construction or other work undertaken by or on behalf of Tenant in, on or
about the Premises, whether prior to or during the Term, or (c) any accident,
injury or damage, howsoever and by whomsoever caused, to any person or property,
occurring in, on or about the Premises; except to the extent such Claims are
caused directly by the gross negligence or willful misconduct of Landlord or its
authorized representatives. In case any action or proceeding be brought against
any of the Indemnitees by reason of any such Claim, Tenant, upon notice from
Landlord, covenants to resist and defend at Tenant's sole expense such action
or-proceeding by counsel reasonably satisfactory to Landlord. The provisions of
this Section 13.a. shall survive the expiration or earlier termination of this
Lease with respect to any injury, illness, death or damage occurring prior to
such expiration or termination.

  b.   Fire and Extended Coverage. Landlord shall procure and maintain in full
       --------------------------
force and effect with respect to the Buildings, including the Tenant
Improvements constructed by Landlord pursuant to Exhibit B (excluding, at
                                                 ---------
Landlord's option, such of the Tenant Improvements which are unusual or
extraordinary for use of the Premises as permitted hereunder, as reasonably
determined by Landlord and noticed to Tenant at the time Landlord approves the
Final Plans pursuant to Exhibit B (the "Above Standard Tenant Improvements"), a
                        ---------
policy or policies of all risk insurance (including sprinkler, vandalism and
malicious mischief coverage, and any other endorsements desired by the Landlord
or required by the holder of any fee or leasehold mortgage on the Real Property,
but excluding, at Landlord's option, the insurance described in Section 13.i.
below) in such amount as Landlord shall determine, but in an amount at least
equal to eighty percent (80%) (or such greater percentage as shall be required
to preclude Landlord from being deemed a coinsurer) ) of the full replacement
cost (including debris removal, and demolition, but excluding the land and the
footings, foundations and installations below the basement level) thereof. Such
insurance, and all other insurance maintained by Landlord under this Lease,
shall be for the sole benefit of Landlord, and the proceeds therefrom shall be
under Landlord's sole control.

  c.   Public Liability. Tenant, at its own cost and expense, shall keep and
       ----------------
maintain in full force and effect during the Term the following insurance
coverages, written by an insurance company licensed by and

                                      12
<PAGE>

admitted to issue insurance in the State of California, with a general
policyholders' rating of "A" or better and a financial size ranking of "Class X"
or higher, in the most recent edition of Best's Insurance Guide, in the form
customary to the locality, (i) commercial general liability insurance, including
contractual liability coverage, insuring Tenant's activities with respect to the
Premises and/or the Buildings against loss, damage or liability for personal
injury or death of any person or loss or damage to property occurring in, upon
or about the Premises, with a minimum coverage of One Million Dollars
($1,000,000) per occurrence/Two Million Dollars ($2,000,000) general aggregate,
plus a Five Million Dollar ($5,000,000) per occurrence/general aggregate
umbrella, (ii) fire damage legal liability insurance and personal/advertising
injury insurance (which shall not be subject to the contractual liability
exclusion), each in the minimum amount of One Million Dollars ($1,000,000),
(iii) medical payments insurance in the minimum amount of Five Thousand Dollars
($5,000), (iv) worker's compensation insurance in statutory amounts, and (v) if
Tenant operates owned, leased or non-owned vehicles on the Property,
comprehensive automobile liability insurance with a minimum coverage of
$1,000,000 per occurrence/Two Million Dollars ($2,000,000) general aggregate;
provided, however, that if, at any time during the Term, Tenant shall have in
full force and effect a blanket policy of public liability insurance with the
same coverage for the Premises as described above in this Section 13.c., as well
as coverage of other premises and properties of Tenant, or in which Tenant has
some interest, the blanket insurance shall satisfy the requirement hereof and be
endorsed to separately apply to the Premises.

  d.   Rental Abatement Insurance. Landlord may keep and maintain in full force
       --------------------------
and effect during the Term rental abatement insurance against abatement or loss
of rents with respect to the Real Property in such amount as determined by
Landlord.

  e.   Insurance Certificates. Tenant shall furnish to Landlord, on or before
       ----------------------
the Commencement Date and thereafter within thirty (30) days prior to the
expiration of each policy, an original certificate of insurance issued by the
insurance carrier of each policy of insurance carried by Tenant pursuant to this
Section 13. The certificates shall expressly provide that the policies shall not
be cancelable or subject to reduction of coverage or otherwise be subject to
modification except after thirty (30) days' prior written notice to the parties
named as insureds. Landlord, its successors and assigns, and any nominee of
Landlord holding any interest in the Premises, including, without limitation,
any ground lessor or the holder of any fee or leasehold mortgage, shall be named
as an additional insured under each policy of insurance maintained by Tenant
pursuant to this Lease other than worker's compensation insurance. The policies
and certificates shall further provide that the coverage shall be primary, and
that any coverage carried by Landlord shall be secondary and noncontributory
with respect to Tenant's policy.

  f.   Tenant's Failure. If Tenant fails to maintain any insurance required by
       ----------------
this Lease, Tenant shall be liable for any loss or cost resulting from the
failure. This Section shall not be deemed to be a waiver of any of Landlord's
rights and remedies under any other provision of this Lease.

  g.   Waiver of Subrogation. Any policy or policies of fire, extended coverage
       ---------------------
or similar casualty insurance which either party obtains in connection with the
Buildings, the Premises, or Tenant's Personal Property shall include a clause or
endorsement denying the insurer any rights of subrogation against the other
party (and the other parties named as additional insureds pursuant to Section
13.e. above) to the extent rights have been waived by the insured prior to the
occurrence of injury or loss. Landlord and Tenant each waives any rights of
recovery against the other (and the other parties named as additional insureds
pursuant to Section 13.e. above) for injury or loss due to hazards insurable by
policies of fire, extended coverage or similar casualty insurance, regardless of
whether such insurance policies or coverage shall actually have been obtained by
the party granting such waiver, and regardless of the cause of such fire or
casualty, including the negligence of the party benefiting from such waiver.
Because this Section 13.g will preclude the assignment of any claim mentioned in
it by way of subrogation or otherwise to an insurance company

                                      13
<PAGE>

or any other person, each party to this Lease agrees immediately to give to each
of its insurance companies written notice of the terms of the mutual waivers
contained in this Section 13.g and to have the insurance policies properly
endorsed, if necessary, to prevent the invalidation of the insurance coverages
by reason of the mutual waivers contained in this Section 13.g.

  h.   Tenant's Property and Fixtures. Tenant shall assume the risk of damage to
       ------------------------------
any of Tenant's furniture, equipment, machinery, goods, supplies or fixtures or
other Personal Property, and to any Alterations which Tenant may make to the
Premises and to the Above Standard Tenant Improvements, and shall insure the
same throughout the Term, for their full replacement cost, under insurance
policies reasonably satisfactory to Landlord (certificates of which shall be
delivered to Landlord as set forth above in Section 13.e). Tenant hereby
releases Landlord from any obligation to insure the foregoing items and from any
liability for loss of or damage to such items, regardless of cause.

  i.   Earthquake and Flood Insurance. In addition to any other insurance
       ------------------------------
policies carried by Landlord in connection with the Buildings, Landlord may
elect to procure and maintain in full force and effect during the Term with
respect to the Buildings a policy of earthquake/volcanic action and flood and/or
surface water insurance, including rental value insurance against abatement or
loss of rent in the case of damage or loss covered under the earthquake/volcanic
and flood and/or surface water insurance, in an amount up to one hundred percent
(100%) of the full replacement cost (including debris removal and demolition) of
the Buildings and the Tenant Improvements (excluding at Landlord's option, the
Above Standard Tenant Improvements).

  14.  Assignment or Sublet.
       ---------------------

  a.   Tenant Shall not assign this Lease or sublet the Premises or any portion
thereof without the prior written consent of Landlord in each instance, which
consent shall not, subject to Landlord's rights under clause (i) below, be
unreasonably withheld. If Tenant desires to assign this Lease or to sublet the
Premises, or any part thereof, Tenant shall give to Landlord written notice of
its intent at least thirty (30) days in advance of the date on which Tenant
desires to assign or sublet the Premises, which notice shall designate the terms
of the proposed assignment or sublet, the identity of the proposed assignee or
sublessee, and shall be accompanied by financial statements of such proposed
assignee or sublessee and such other information regarding such party and its
business and reputation as shall be required by Landlord to evaluate the
proposed assignment or sublet. Landlord shall have thirty (30) days after
receipt of Tenant's written notice and the above specified information within
which to notify Tenant in writing that Landlord elects to (i) terminate this
Lease, in the case of a proposed assignment, or to terminate this Lease as to
that portion of the Premises to be sublet, in the case of a proposed sublet,
(ii) consent to the proposed assignment or sublet as described in Tenant's
notice, or (iii) reasonably refuse to consent to Tenant's proposed assignment or
sublet, stating the reasons for such refusal. If Landlord fails to notify Tenant
in writing of its election within the thirty (30) day period, Landlord shall be
deemed to have made the election in clause (iii) above. No consent by Landlord
to any assignment or sublet shall be deemed to be a consent to a use not
permitted under this Lease, to any act in violation of this Lease or to any
subsequent assignment or sublet. No assignment or sublet by Tenant shall relieve
Tenant of any liability theretofore or thereafter arising under this Lease. Any
attempted assignment or sublet by Tenant in violation of the terms and covenants
of this Section shall be void. Notwithstanding the foregoing, Landlord shall not
have the right described in clause (i) above with respect to any proposed sublet
of the Building E Premises or any portion thereof if the term of such proposed
sublet shall expire on or prior to the third annual anniversary of the Rent
Commencement Date.

  b.   Processing Expenses. Tenant shall pay to Landlord, as Landlord's cost of
       -------------------
processing each proposed assignment or subletting (whether or not the same is
ultimately approved by Landlord or

                                      14
<PAGE>

consummated by Tenant), an amount equal to the sum of (i) Landlord's reasonable
attorneys' and other professional fees, plus (ii) the sum of $1000.00 for the
cost of Landlord's administrative, accounting and clerical time (collectively,
"Processing Costs"). Notwithstanding anything to the contrary herein, Landlord
shall not be required to process any request for Landlord's consent to an
assignment or subletting until Tenant has paid to Landlord the amount of
Landlord's estimate of the Processing Costs. When the actual amount of the
Processing Costs is determined, it shall be reconciled with Landlord's estimate,
and any payments or refunds required as a result thereof shall promptly
thereafter be made by the parties.

  c.   Consideration to Landlord. In the event of any assignment or sublease,
       -------------------------
other than an assignment or sublease pursuant to Section 14.g. below, Landlord
shall be entitled to receive, as additional rent hereunder, seventy-five percent
(75%) of any consideration (including, without limitation, payment for leasehold
improvements and any "Leasehold Profit" as defined below) paid by the assignee
or subtenant for the assignment or sublease and, in the case of a sublease, the
excess of the amount of rent paid for the sublet space by the subtenant over the
amount of Monthly Base Rent under Section 4 above and Operating Expenses under
Section 5 above and Assignment or Subletting Costs (amortized as set forth
below), attributable to the sublet space for the corresponding month.
"Assignment or Subletting Costs" shall mean, on an amortized basis over the term
of this Lease, the Excess Cost (as defined in Exhibit B attached hereto) paid by
                                              ---------
Tenant for the Tenant Improvements, excluding such of the Excess Cost as shall
be attributable to the Above Standard Tenant Improvements, or the items and/or
costs described in Paragraphs 1.f.ii. and 1.f. iii.C. of Exhibit B attached
                                                         ---------
hereto, provided that, as a condition to Tenant recapturing the Assignment or
Subletting Costs, Tenant and Landlord shall have agreed in writing as to the
amount thereof with respect to the Building F Premises within thirty (30) days
of the Commencement Date and as to the amount thereof with respect to the
Building E Premises within thirty (30) days after the Tenant Improvements
therein shall have been Substantially Completed. "Leasehold Profit" shall be the
value allocated to the leasehold between the parties to the assignment or
sublease, but in no event less than the excess of the present value of the fair
market rent of the Premises for the remaining term of this Lease at the time of
such assignment or sublease, over the Base Rent payable hereunder for such
remaining term, as reasonably determined by Landlord and communicated to Tenant
at the time of Landlord's consent to the assignment or sublease. Upon Landlord's
request, Tenant shall direct any subtenant or assignee to pay the directly to
Landlord the amounts due to it pursuant to this Section 14.c. on account of such
sublease or assignment. If there is more than one sublease under this Lease, the
amounts (if any) to be paid by Tenant to Landlord pursuant to this Section 14.c.
shall be separately calculated for each sublease and amounts due Landlord with
regard to any one sublease may not be offset against rental and other
consideration pertaining to or due under any other sublease.

  d.   Documentation. No permitted assignment or subletting by Tenant shall be
       -------------
effective until there has been delivered to Landlord a fully executed
counterpart of the assignment or sublease which expressly provides that (i) in
the case of a sublease, the subtenant may not assign its sublease or further
sublet the sublet space without Landlord's prior written consent, (ii) in the
case of an assignment, the assignee assumes all of Tenant's obligations under
this Lease arising on or after the date of the assignment, and (iii) in the case
of a sublease, the subtenant agrees to be and remain jointly and severally
liable with Tenant to Landlord for the payment of Rent pertaining to the sublet
space in the amount set forth in the sublease, and for the performance of all of
the terms and provisions of this Lease pertaining to the sublet space. In
addition to the foregoing, no assignment or sublease by Tenant shall be
effective until there has been delivered to Landlord a fully executed
counterpart of Landlord's consent to assignment or sublease form, as applicable.
The failure or refusal of a subtenant or assignee to execute any such instrument
shall not release or discharge the subtenant or assignee from its liability as
set forth above. Notwithstanding the foregoing, no subtenant or assignee shall
be permitted to occupy the Premises unless and until such subtenant or assignee
provides Landlord with certificates evidencing that such subtenant or assignee
is carrying all insurance coverage required of it under this Lease.
                                      15
<PAGE>

  e.   No Merger. Without limiting any of the provisions of this Section 14, the
       ---------
voluntary or other surrender of this Lease by Tenant, or a mutual cancellation
by Landlord and Tenant, shall not work a merger, and shall, at the option of
Landlord, terminate all or any existing subleases or subtenancies or, at the
option of Landlord, operate as an assignment to Landlord of any or all such
subleases or subtenancies. If Landlord does elect that such surrender or
cancellation operate as an assignment of such subleases or subtenancies,
Landlord shall in no way be liable for any previous act or omission by Tenant
under the subleases or for the return of any deposit(s) under the subleases that
have not been actually delivered to Landlord, nor shall Landlord be bound by any
sublease modification(s) executed without Landlord's consent or for any advance
rental payment by the subtenant in excess of one month's rent.

  f.   Indirect Assignments. For purposes of this Section 14, the following
       --------------------
events shall be deemed an assignment or sublease, as appropriate: (i) the
issuance of equity interests (whether stock, partnership interests or otherwise)
in Tenant or any subtenant or assignee, or any entity controlling any of them,
to any person or group of related persons, in a single transaction or a series
of related or unrelated transactions, such that, following such issuance, such
person or group shall have Control (as defined below) of Tenant or any subtenant
or assignee; (ii) a transfer of Control of Tenant or any subtenant or assignee,
or any entity controlling any of them, in a single transaction or a series of
related or unrelated transactions (including, without limitation, by
consolidation, merger, acquisition or reorganization), except that the transfer
of outstanding capital stock or other listed equity interests by persons or
parties other than "insiders" within the meaning of the Securities Exchange Act
of 1934, as amended, through the "over-the-counter" market or any recognized
national or international securities exchange, shall not be included in
determining whether Control has been transferred; (iii) a reduction of Tenant's
assets to the point that this Lease and/or other leases are substantially
Tenant's only asset(s); or (iv) a change or conversion in the form of entity of
Tenant, any subtenant or assignee, or any entity controlling any of them, which
has the effect of limiting the liability of any of the partners, members or
other owners of such entity. "Control" shall mean direct or indirect ownership
of 50% or more of all of the voting stock of a corporation or 50% or more of the
voting legal or equitable interest in any other business entity, or the power to
direct the management and operations of any entity (by equity ownership,
contract or otherwise).

  g.   Affiliates: Successors. Notwithstanding anything to the contrary in
       ----------------------
Section 14.a or Section 14.c., but subject to the other provisions of this
Section 14, Tenant may assign this Lease or sublet the Premises or any portion
thereof, without Landlord's consent, to any partnership, corporation or other
entity which controls, is controlled by, or is under common control with Tenant
(control being defined for such purposes as ownership of 50% or more of all of
the voting stock of a corporation or 50% or more of the voting legal or
equitable interest in any other business entity, and the power to direct the
management and operations of, the relevant entity) (an "Affiliate") or to any
partnership, corporation or other entity resulting from a merger or
consolidation with Tenant or which acquires all or substantially all of Tenant's
assets (through a transfer of assets or equity interests in Tenant) as a going
concern and such assets include substantial assets other than this Lease (a
"Successor"), provided that (i) Landlord receives at least ten (10) days' prior
written notice of the assignment or subletting, in which Tenant shall expressly
confirm that Tenant remains primarily liable (together with the assignee in the
event of an assignment) for all of the obligations of the Tenant under this
Lease, except that if such prior notice shall be prohibited under applicable
Legal Requirements, then such notice shall be given as promptly as is
permissible under applicable Legal Requirements, (ii) in the case of an
assignment to a Successor, the Successor's net worth is not less than Tenant's
net worth immediately prior to such assignment (or series of transactions of
which such assignment is a part), (iii) in the case of a subletting or
assignment to an Affiliate, the Affiliate remains an Affiliate for the duration
of the subletting or the balance of the term in the event of an assignment, (iv)
Landlord receives a fully executed copy of the assignment or sublease agreement
between Tenant and the Affiliate or Successor at least ten (10) days prior to
the effective date of such assignment or sublease, in which the Affiliate or
Successor, as the case may be, assumes (in the event of an assignment) all of
Tenant's obligations under this Lease, and agrees (in the event

                                      16
<PAGE>

of a sublease) that such subtenant will, at Landlord's election, attorn directly
to Landlord in the event that this Lease is terminated for any reason, except
that if such prior delivery of the assignment or sublease shall be prohibited
under applicable Legal Requirements, then such delivery shall be made as
promptly as is permissible under applicable Legal Requirements, (v) the use of
the Premises will not change from the use of the Premises prior to such
assignment (or series of transactions of which such assignment is a part) or
subletting, and (vi) in the case of an assignment, the essential purpose of such
assignment is to transfer an active, ongoing business with substantial assets in
addition to this Lease, and in the case of an assignment or sublease the
transaction is for legitimate business purposes unrelated to this lease and the
transaction is not a subterfuge by Tenant to avoid it obligations under this
Lease or the restrictions on assignment and subletting contained herein.

  15.  Default.
       -------

  a.   Tenant's Default. A material breach of this Lease by Tenant shall exist
       ----------------
if any of the following events (severally, "Event of Default"; collectively,
"Events of Default") shall occur: (i) if Tenant shall have failed to pay Base
Rent, Tenant's Percentage Share of increased Operating Expenses, or any other
sum required to be paid hereunder when due, including any interest due under
Section 3, and such failure shall continue for five (5) days after written
notice thereof from Landlord, except that Landlord shall only be required to
give two (2) such notices in any calendar year, and thereafter any such failure
by Tenant shall constitute an Event of Default without the requirement of notice
from Landlord; (ii) if Tenant shall have failed to perform any term, covenant or
condition of this Lease except those requiring the payment of money, and Tenant
shall have failed to cure the breach within thirty (30) days after written
notice from Landlord if the breach could reasonably be cured within the thirty
(30) day period; provided, however, if the failure could not reasonably be cured
within the thirty (30) day period, then Tenant shall not be in default unless it
has failed to promptly commence and thereafter continue to make diligent and
reasonable efforts to cure the failure as soon as practicable as reasonably
determined by Landlord; (iii) if Tenant shall have assigned its assets for the
benefit of its creditors; (iv) if the sequestration of, attachment of, or
execution on, any material part of the property of Tenant or on any property
essential to the conduct of Tenant's business shall have occurred, and Tenant
shall have failed to obtain a return or release of the property within thirty
(30) days thereafter, or prior to sale pursuant to any sequestration, attachment
or levy, whichever is earlier; (v) if Tenant shall have abandoned the Premises;
(vi) if a court shall have made or entered any decree or order adjudging Tenant
to be insolvent, or approving as properly filed a petition seeking
reorganization of Tenant, or directing the winding up or liquidation of Tenant,
and the decree or order shall have continued for a period of thirty (30) days;
(vii) if Tenant shall make or suffer any transfer which constitutes a fraudulent
or otherwise avoidable transfer under any provision of the federal Bankruptcy
Laws or any applicable state law; or (viii) if Tenant shall have failed to
comply with the provisions of Sections 22 or 24 of this Lease within the time
periods stated therein. An Event of Default shall constitute a default under
this Lease.

  b.   Remedies Upon Tenant's Default. Upon an Event of Default, Landlord shall
       ------------------------------
have the following remedies, in addition to all other rights and remedies
provided by law, equity, statute or otherwise provided in this Lease, to which
Landlord may resort cumulatively or in the alternative:

       (i) Landlord has the remedy described in California Civil Code Section
1951.4 (a landlord may continue the lease in effect after the tenant's breach
and abandonment and recover rent as it becomes due, if the tenant has the right
to sublet and assign subject only to reasonable limitations), and may continue
this Lease in full force and effect, and this Lease shall continue in full force
and effect as long as Landlord does not terminate Tenant's right to possession,
and Landlord shall have the right to collect Rent when due. During the period
Tenant is in default, Landlord may enter the Premises and relet it, or any part
of it, to third parties for Tenant's account, provided that any Rent in excess
of the Rent due hereunder shall be payable

                                      17
<PAGE>

to Landlord. Tenant shall be liable immediately to Landlord for all costs
Landlord incurs in reletting the Premises, including, without limitation,
brokers' commissions, expenses of cleaning and redecorating the Premises
required by the reletting and like costs. Reletting may be for a period shorter
or longer than the remaining Term of this Lease. Tenant shall pay to Landlord
the Rent and other sums due under this Lease on the dates the Rent is due, less
the Rent and other sums Landlord receives from any reletting. No act by Landlord
allowed by this Subsection (i) shall terminate this Lease unless Landlord
notifies Tenant in writing that Landlord elects to terminate this Lease.

       (ii) Landlord may terminate Tenant's right to possession of the Premises
at any time by giving written notice to that effect. No act by Landlord other
than giving written notice to Tenant of such termination shall terminate this
Lease. Acts of maintenance, efforts to relet the Premises or the appointment of
a receiver on Landlord's initiative to protect Landlord's interest under this
Lease shall not constitute a termination of Tenant's right to possession. On
termination, Landlord shall have the right to remove all personal property of
Tenant and store it at Tenant's cost and to recover from Tenant as damages: (a)
the worth at the time of award of unpaid Rent and other sums due and payable
which had been earned at the time of termination; plus (b) the worth at the time
of award of the amount by which the unpaid Rent and other sums due and payable
which would have been payable after termination until the time of award exceeds
the amount of the Rent loss that Tenant proves could have been reasonably
avoided; plus (c) the worth at the time of award of the amount by which the
unpaid Rent and other sums due and payable for the balance of the Term after the
time of award exceeds the amount of the Rent loss that Tenant proves could be
reasonably avoided; plus (d) any other amount necessary to compensate Landlord
for all the detriment proximately caused by Tenant's failure to perform Tenant's
obligations under this Lease, or which, in the ordinary course of things, would
be likely to result therefrom, including, without limitation, any costs or
expenses incurred by Landlord: (1) in retaking possession of the Premises,
including reasonable attorneys' fees and costs therefor; (2) maintaining or
preserving the Premises for reletting to a new tenant, including repairs or
alterations to the Premises for the reletting; (3) leasing commissions; (4) any
other costs necessary or appropriate to relet the Premises; and (5) at
Landlord's election, such other amounts in addition to or in lieu of the
foregoing as may be permitted from time to time by California Civil Code Section
1951.2 or any other laws of the State of California.

The "worth at the time of award" of the amounts referred to in Subsections
(ii)(a) and (ii)(b) is computed by allowing interest at the lesser of eighteen
percent (18%) per annum or the maximum rate permitted by law, on the unpaid Rent
and other sums due and payable from the date due through the date of award. The
"worth at the time of award" of the amount referred to in Subsection (ii)(c) is
computed by discounting the amount at the discount rate of the Federal Reserve
Bank of San Francisco at the time of award, plus one percent (1%). Tenant waives
redemption or relief from forfeiture under California Code of Civil Procedure
Sections 1174 and 1179, or under any other present or future law, if Tenant is
evicted or Landlord takes possession of the Premises by reason of any default of
Tenant hereunder.

  c.   Landlord's Default. Landlord shall not be deemed to be in default in the
       ------------------
performance of any obligation required to be performed by Landlord hereunder
unless and until Landlord has failed to perform the obligation within thirty
(30) days after receipt of written notice by Tenant to Landlord specifying the
obligation Landlord has failed to perform; provided, however, that if the nature
of Landlord's obligation is such that more than thirty (30) days are required
for its performance, then Landlord shall not be deemed to be in default if
Landlord shall commence the performance of such obligation within the thirty
(30) day period and thereafter shall diligently prosecute the same to
completion.

  16.  Landlord's Right to Perform Tenant's Covenants.
       -----------------------------------------------

  If Tenant shall at any time fail to make any payment or perform any other act
on its part to be made or

                                      18
<PAGE>

performed under this Lease, Landlord may, but shall not be obligated to, make
the payment or perform any other act to the extent Landlord may deem desirable
and, in connection therewith, pay expenses and employ counsel. Any payment or
performance by Landlord shall not waive or release Tenant from any obligations
of Tenant under this Lease. All sums so paid by Landlord, and all penalties,
interest and costs in connection therewith, shall be due and payable by Tenant
on the next day after any payment by Landlord, together with interest thereon at
the Interest Rate, from that date to the date of payment thereof by Tenant to
Landlord, plus collection costs and attorneys' fees. Landlord shall have the
same rights and remedies for the nonpayment thereof as in the case of default in
the payment of Base Rent.

  17.  Letter of Credit.
       ----------------

  a. Within ten (10) Business Days after the date of this Lease, Tenant shall
deliver to Landlord the Letter of Credit described below as security for
Tenant's performance of all of Tenant's covenants and obligations under this
Lease; provided, however, that neither the Letter of Credit nor any proceeds
therefrom (the "Letter of Credit Proceeds") shall be deemed an advance rent
deposit or an advance payment of any other kind, or a measure or limitation of
Landlord's damages or constitute a bar or defense to any of the Landlord's other
remedies under this Lease or at law upon Tenant's default. The Letter of Credit
shall be maintained in effect from the date of this Lease through sixty (60)
days after the expiration or earlier termination of the Term, and on or prior to
the expiration of such sixty (60) day period, Landlord shall return to Tenant
the Letter of Credit (unless presented for payment as provided herein) and any
Letter of Credit Proceeds then held by Landlord (other than those held for
application by Landlord as provided below, including application to cure any
failure by Tenant to restore the Premises as required by this Lease upon the
surrender thereof); provided, however, that in no event shall any such return be
construed as an admission by Landlord that Tenant has performed all of its
obligations hereunder. Landlord shall not be required to segregate the Letter of
Credit Proceeds from its other funds and no interest shall accrue or be payable
to Tenant with respect thereto. Landlord may (but shall not be required to) draw
upon the Letter of Credit and use the Letter of Credit Proceeds or any portion
thereof to cure any Event of Default by Tenant under this Lease or to compensate
Landlord for any damage Landlord incurs as a result of Tenant's failure to
perform any of its obligations hereunder where Landlord has not given Tenant the
notice required for such failure to constitute an Event of Default solely
because there exist circumstances under which Landlord is enjoined or otherwise
prevented by operation of law from giving to Tenant such notice, it being
understood that any use of the Letter of Credit Proceeds shall not constitute a
bar or defense to any of Landlord's other remedies under this Lease. In such
event and upon written notice from Landlord to Tenant specifying the amount of
the Letter of Credit Proceeds so utilized by Landlord and the particular purpose
for which such amount was applied, Tenant shall immediately deliver to Landlord
an amendment to the Letter of Credit or a replacement thereof in an amount equal
to one hundred percent (100%) of the amount specified below for the applicable
period. Tenant's failure to deliver such amendment or replacement to Landlord
within five (5) days of Landlord's notice shall constitute an Event of Default
hereunder. In the event Landlord shall draw upon the Letter of Credit as
provided herein, and shall not fully utilize the Letter of Credit Proceeds as
provided above, upon Tenant's cure of the condition giving rise to such
permitted draw by Landlord, and Landlord's acceptance of such cure, if Tenant
shall deliver the amendment or replacement specified above so that the Letter of
Credit amount is equal to one hundred percent (100%) of the amount specified
below for the applicable period, Landlord shall promptly return to Tenant the
balance of the Letter of Credit Proceeds then held by Landlord. No lessor under
any ground or underlying lease or holder of or beneficiary under a mortgage or
deed of trust, nor any purchaser at any judicial or private foreclosure sale of
the Property or any portion thereof, shall be responsible to Tenant for such
Letter of Credit or any Letter of Credit Proceeds unless such lessor, holder or
purchaser shall have actually received the same.

  b. As used herein, Letter of Credit shall mean an unconditional, irrevocable
letter of credit (hereinafter referred to as the "Letter of Credit") issued at
Tenant's sole expense by the San Francisco office of a major

                                      19
<PAGE>

national bank satisfactory to Landlord (the "Bank"), naming Landlord as
beneficiary, and in form and substance satisfactory to Landlord, in the amount
of Three Million Two Hundred Fifty Thousand Dollars ($3,250,000.00) during the
period from the delivery date thereof through the fourth annual anniversary of
the first Commencement Date to occur hereunder, and reducing in amount on the
fourth annual anniversary of such first Commencement Date and each annual
anniversary of such first Commencement Date thereafter by an amount equal to
twenty percent (20%) of the original amount of the Letter of Credit; provided,
however, that if on the date the Letter of Credit amount would otherwise reduce,
an Event of Default, or default that with notice or the passage of time or both
could mature into an Event of Default, shall have occurred and be continuing,
the Letter of Credit amount shall not reduce on such date and shall not
thereafter reduce until such Event of Default or default shall have been cured.
The Letter of Credit shall be for a one-year or, at Tenant's election, longer,
term and shall provide: (i) that Landlord may make partial and multiple draws
thereunder, up to the face amount thereof, (ii) that Landlord may draw upon the
Letter of Credit up to the full amount thereof, as determined by Landlord, and
the Bank will pay to Landlord the amount of such draw upon receipt by the Bank
of a sight draft signed by Landlord and accompanied by a written certification
from Landlord to the Bank stating either: (a) that an Event of Default has
occurred and is continuing under this Lease, or (b) that an uncured failure by
the Tenant to perform one or more of its obligations has occurred under this
Lease and there exist circumstances under which Landlord is enjoined or
otherwise prevented by operation of law from giving to Tenant a written notice
which would be necessary for such failure of performance to constitute an Event
of Default under this Lease, or (c) that Landlord has not received notice from
the Bank that the Letter of Credit will be renewed by the Bank for at least one
(1) year beyond the then relevant expiration date and Tenant has not furnished
Landlord with a replacement Letter of Credit as hereinafter provided, or (d)
that Bank no longer meets the requirements set forth above and Tenant has not
furnished Landlord with a replacement Letter of Credit as required hereunder
from a Bank meeting such requirements; and (iii) that, in the event of
Landlord's assignment or other transfer of its interest in this Lease, the
Letter of Credit shall be freely transferable by Landlord, without charge and
without recourse, to the assignee or transferee of such interest and the Bank
shall confirm the same to Landlord and such assignee or transferee. The Letter
of Credit shall further provide that a draw thereon pursuant to clause (ii)(c)
above may only be made during the thirty (30) day period preceding the then
applicable expiration date of the Letter of Credit. In the event that the Bank
shall fail to notify Landlord that the Letter of Credit will be renewed for at
least one (1) year beyond the then applicable expiration date, and Tenant shall
not have delivered to Landlord, at least thirty (30) days prior to the relevant
annual expiration date, a replacement Letter of Credit in the amount required
hereunder and otherwise meeting the requirements set forth above, then Landlord
shall be entitled to draw on the Letter of Credit as provided above, and shall
hold and apply the proceeds of such draw as Letter of Credit Proceeds pursuant
to Paragraph 17.b above.

  In the event that Tenant shall not deliver the Letter of Credit to Landlord in
the form and amount required hereby on or prior to the date required hereby,
then in lieu thereof Tenant shall deliver to Landlord cash in the amount of the
so required Letter of Credit, and Tenant's failure to deliver either cash or the
Letter of Credit shall be deemed an Event of Default hereunder. In addition to
Landlord's other rights and remedies by reason of such Event of Default, each
day which passes after the applicable due date for the Letter of Credit until
and including the day on which Tenant shall deliver such cash or Letter of
Credit to Landlord shall be chargeable to Tenant as a day of Tenant Delay
pursuant to Section 2 above of this Lease.

18.     Surrender of Premises.
        ---------------------

  By taking possession of the Premises, subject to Landlord's performance of its
obligations under Section 7, Tenant shall be deemed to have accepted the
Premises and the Property in good, clean and completed condition and repair,
subject to all applicable laws, codes and ordinances. On the Expiration Date or
earlier termination of this Lease, Tenant shall surrender the Premises to
Landlord in its condition as of the

                                      20
<PAGE>

Commencement Date, normal wear and tear excepted. Tenant shall remove from the
Premises all of Tenant's Personal Property and any Alterations required to be
removed pursuant to Section 9 of this Lease. Tenant shall repair any damage or
perform any restoration work required by the removal. If Tenant fails to timely
remove any Personal Property or Alterations as aforesaid, Landlord may remove
the property and store and/or dispose of the same at Tenant's expense, including
interest at the Interest Rate. If the Premises are not so surrendered at the
termination of this Lease, Tenant shall indemnify Landlord against all Claims
resulting from delay by Tenant in so surrendering the Premises, including,
without limitation, any claims made by any succeeding tenant, losses to Landlord
due to lost opportunities to lease to succeeding tenants, and attorneys' fees
and costs. Tenant shall give written notice to Landlord at least thirty (30)
days prior to vacating the Premises and shall meet with Landlord for a joint
inspection of the Premises at the time of vacating. In the event of Tenant's
failure to give such notice or participate in such joint inspection, Landlord's
inspection at or after Tenant's vacating the Premises shall conclusively be
deemed correct for purposes of determining Tenant's responsibility for removal
of Alterations and repairs and restoration of the Premises.

19.     Holding Over.
        ------------

  If Tenant remains in possession of all or any part of the Premises after the
expiration of the Term or the earlier termination of this Lease without
Landlord's prior written consent, the tenancy shall be a tenancy at sufferance
only and shall not constitute a renewal or extension for any further term,
regardless of whether Landlord shall accept Rent for any such period. In such
event, Base Rent shall be increased in an amount equal to the greater of (i) two
hundred percent (200%) of the Base Rent during the last month of the Term
(including any extensions), and (ii) two hundred percent (200%) of the fair
market value of the Premises, and any other sums due under this Lease shall be
payable in the amount, and at the times, specified in this Lease. The tenancy
shall be subject to every other term, condition, covenant and agreement
contained in this Lease, except that any renewal or extension option in favor of
Tenant shall not be applicable. No such increase shall impair Landlord's other
rights and remedies against Tenant by reason of such holding over by Tenant, and
Tenant shall vacate the Premises immediately upon Landlord's request.

20.     Access to Premises.
        ------------------

  Tenant shall permit Landlord and its agents to enter the Premises at all
reasonable times upon reasonable prior notice, except in the case of an
emergency (in which event entry may be made when necessary and without notice),
to inspect the Premises, to post Notices of Nonresponsibility and similar
notices, to show the Premises to interested parties such as prospective
mortgagees, purchasers and tenants to provide any services required of Landlord
hereunder, to make necessary alterations, additions, improvements or repairs
either to the Premises, the Buildings, or other premises within the Buildings,
and to discharge Tenant's obligations hereunder when Tenant has failed to do so
within a reasonable time after written notice from Landlord. No such entry shall
constitute a constructive eviction or give rise to an abatement of Rent
hereunder, constitute a constructive eviction, or otherwise diminish Tenant's
obligations under this Lease. In exercising its rights under this Section 20,
Landlord shall at all times endeavor to minimize interference with Tenant's
operations, to the extent practicable. During the last year of the Term,
Landlord shall have the right to erect on the exterior of the Premises and/or on
the exterior or in the Common Areas of the Buildings and the Property suitable
signs indicating that the Premises are available for lease.

21.     Signs.
        -----

  a.    General. The size, design, color, location and other physical aspects of
        -------
any sign in or on the Premises shall be subject to the CC&R's, Rules, Landlord's
approval prior to installation, and to all Legal Requirements. The costs of any
permitted sign, and the costs of its installation, maintenance and removal,

                                      21
<PAGE>

shall be at Tenant's sole expense and shall be paid within ten (10) days of
Tenant's receipt of a bill from Landlord for the costs. In no event shall Tenant
be permitted to place any sign, logo or other identification on the exterior of
the Buildings, in the Building's Common Areas (other than on a Building
directory maintained to identify the Building's tenants), or upon the Property,
or which is inside the Premises but visible from outside of the Premises (other
than upon the door(s) to the Premises).

  b.   Exterior Building Signage. Notwithstanding Section 21.a., so long as the
       -------------------------
Tenant under this Lease (i) is the Tenant originally named under this Lease in
the Basic Lease Information, (ii) is in occupancy pursuant to this Lease of at
least seventy-five percent (75%) of the portion of the Premises originally
demised under this Lease in the applicable Building, and (iii) is not in default
of any of its obligations hereunder beyond the expiration of any applicable
grace or cure period, Tenant shall be permitted to maintain identification
signage at the top of one exterior side of the Building in which the applicable
portion of the Premises is located, in a location reasonably approved by
Landlord. The installation, maintenance and removal of Tenant's signage pursuant
to this Section 21.b. shall be performed by Tenant at Tenant's expense, but in
coordination with Landlord and its reasonable installation procedures and
requirements, or at Landlord's option, by Landlord at Tenant's expense. Such
signage of Tenant shall be subject to Landlord's prior approval and all Legal
Requirements, and shall be limited to Tenant's name and/or logo. If Tenant shall
fail to meet the signage conditions specified herein, Landlord may immediately
remove Tenant's signage at Tenant's expense, and Tenant's signage rights
pursuant to this Section 21.b. shall thereafter forever cease and terminate;
provided, however, that if applicable Legal Requirements do not require removal
--------  -------
of such signage prior to the expiration of the thirty (30) day period
hereinafter provided, Landlord shall not remove such signage unless it shall
have given Tenant thirty (30) days' prior notice of the signage conditions
Tenant has failed to meet, and such failure continues after the expiration of
such thirty (30) day period. Upon the expiration or earlier termination of this
Lease, Tenant shall, at Tenant's expense, or at Landlord's option Landlord
shall, at Tenant's expense, remove Tenant's signage and repair any damage to the
applicable Building caused by such removal.

  22.  Subordination.
       -------------

  a.   Subordinate Nature. Except as provided in Subsection b., this Lease is
       ------------------
subject and subordinate to all ground and underlying leases, mortgages and deeds
of trust which now or may hereafter affect the Real Property or any portion
thereof, to the CC&R's, and to all renewals, modifications, consolidations,
replacements and extensions of the foregoing, without the necessity of any
further documentation evidencing such subordination. Notwithstanding such self-
operative subordination, within ten (10) Business Days after Landlord's written
request therefor, Tenant shall execute any and all documents required by
Landlord, the lessor under any ground or underlying lease ("Ground Lessor"), or
the holder or holders of any mortgage or deed of trust ("Holder"), evidencing
this Lease to be subordinate to the lien of any such lease, mortgage or deed of
trust, as the case may be. Tenant hereby irrevocably appoints Landlord as
Tenant's attorney-in-fact to execute and deliver any such instrument in the name
of Tenant if Tenant fails to do so within such time. If the interest of Landlord
in the Real Property or the Buildings is transferred to any Ground Lessor or
Holder pursuant to or in lieu of proceedings for enforcement of any such lease,
mortgage, or deed of trust, Tenant shall immediately and automatically attorn to
the Ground Lessor or Holder, and this Lease shall continue in full force and
effect as a direct lease between the Ground Lessor or Holder and Tenant on the
terms and conditions set forth herein.

b.   Possible Priority of Lease. If a Ground Lessor or a Holder advises Landlord
     --------------------------
that it desires or requires this Lease to be prior and superior to a lease,
mortgage or deed of trust, Landlord may notify Tenant. Within seven (7) Business
Days of Landlord's notice, Tenant shall execute, have acknowledged and deliver
to Landlord any mad all documents or instruments, in the reasonable form
presented to Tenant, which Landlord Ground Lessor or Holder deems necessary or
desirable to make this Lease prior and superior to

                                      22
<PAGE>

the lease, mortgage or deed of trust.

  c.   Lease Modification. If, in connection with obtaining financing for the
       ------------------
Real Property or any portion thereof, any Holder or Ground Lessor shall request
reasonable modification to this Lease as a condition to such ground lease or
financing, Tenant shall execute and deliver to Landlord, within ten (10)
Business Days of Landlord's request, any such modification agreement so
requested, provided such modifications do not materially adversely affect
Tenant's rights or materially increase Tenant's obligations hereunder.

  d.   Nondisturbance Agreement. It shall be a condition to the subordination of
       ------------------------
this Lease to any Superior Interest created after the date of this Lease (as
distinguished from any Superior Interest in effect as of the date of this Lease,
or any amendment or modification thereto), that Tenant shall receive from the
Ground Lessor or Holder, as applicable, of such Superior Interest a so-called
non-disturbance agreement in the form reasonably required by such Ground Lessor
or Holder. If in order to obtain such non-disturbance agreement Landlord is
required to pay any fee or charge to such Ground Lessor or Holder, Tenant shall
either pay such fee or charge upon notice thereof from Landlord, or Landlord
shall be deemed released from its obligation to obtain such non-disturbance
agreement and delivery of the same to Tenant shall no longer be a condition of
the subordination of this Lease thereto.

23.    Transfer of the Property.
       ------------------------

  Upon transfer of the Real Property and assignment of this Lease, Landlord
shall be entirely freed and relieved of all liability under any and all of its
covenants and obligations contained in or derived from this Lease occurring
after the consummation of the transfer and assignment, and if Landlord shall
transfer the Letter of Credit and Letter of Credit Proceeds, if any, to the
transferee of Landlord's interest in the Real Property, Landlord shall be
released from all liability for the Letter of Credit and Letter of Credit
Proceeds and the transferee shall be deemed to have assumed liability thereafter
arising with respect to the same. Tenant shall attorn to any entity purchasing
or otherwise acquiring the Premises at any sale or other proceeding.

24.    Estoppel Certificates; Financial Statements.
       -------------------------------------------

  Within ten (10) Business Days following written request by Landlord from time
to time throughout the Term, Tenant shall execute and deliver to Landlord an
estoppel certificate in the form attached hereto as Exhibit F, duty completed by
                                                    ---------
Tenant. At the request of Landlord from time to time during the Term, Tenant
shall provide to Landlord its current financial statements or other information
setting forth Tenant's financial condition and net worth. Landlord shall use
such documentation solely for purposes of this Lease and in connection with the
ownership, financing, management and disposition of the Real Property, and shall
not disclose such information to any party other than for such purposes.

25.    Mortgagee Protection.
       --------------------

  In the event of any default on the part of Landlord, Tenant will give notice
by registered or certified mail to each Ground Lessor and Holder whose identity
has been disclosed to Tenant, and shall offer the Ground Lessor or Holder a
reasonable opportunity after such notice (but in no event less than thirty (30)
days) to cure the default, including time to obtain possession of the Property
or the Premises by lease termination, power of sale or a judicial foreclosure
(as applicable), if such should prove necessary to effect a cure. In no event
shall any Ground Lessor or Holder in any way or to any extent be: (a) liable for
any act or omission of any prior Landlord in contravention of any provision of
this Lease; or (b) subject to any offsets, claims or defenses which Tenant might
have against any prior Landlord; or (c) bound by any Rent which Tenant

                                      23
<PAGE>

might have paid for more than thirty (30) days in advance to any prior Landlord;
or (d) bound by any agreement or modification of this Lease made without such
Ground Lessor's or Holder's written consent. Tenant agrees that if any Ground
Lessor or Holder acquires possession of the Premises or title to the Real
Property as a result of termination of its ground lease or foreclosure of such
Holder's deed of trust or other security instrument, as applicable, the
acceptance of a lease surrender or deed in lieu of such foreclosure, or
otherwise, the provisions of Section 36 below shall be applicable to liability
of such Ground Lessor or Holder as successor Landlord under this Lease.

26.    Attorneys' Fees.
       ---------------

  If either party shall bring any action or legal proceeding for damages for an
alleged breach of any provision of this Lease, to recover rent or other sums
due, to terminate the tenancy of the Premises or to enforce, protect or
establish any term, condition or covenant of this Lease or right of either
party, the prevailing party shall be entitled to recover, as a part of the
action or proceedings, or in a separate action brought for that purpose,
reasonable attorneys' fees and court costs as may be fixed by the court or jury.
The prevailing party shall be the party which secures a final judgment in its
favor, provided that if the party bringing any action shall dismiss the same
without the consent of the other party, the other party shall be deemed the
prevailing party.

27.    Brokers.
       -------

  Tenant warrants and represents that it has had no dealings with any real
estate broker or agent in connection with the negotiation of this Lease, except
for any brokers(s) specified in the Basic Lease Information, and that it knows
of no other real estate broker or agent who is or might be entitled to a fee,
commission or other compensation in connection with this Lease.

28.    Parking.
       -------

  Tenant shall have the right to park in the parking facilities on the Land, in
common with other: tenants of the Property, upon such terms and conditions as
may from time to time be established by Landlord. There shall be no charge for
any portion of the parking facilities which is not reserved. Tenant agrees not
to use in excess of its proportionate share (i.e. the rentable square footage of
the Premises in proportion to the rentable square footage of all buildings on
the Land) of the parking facilities on the Land and agrees to cooperate with
Landlord and other tenants in the use of the parking facilities. Landlord
reserves the right, in its absolute discretion, to determine whether the parking
facilities are becoming crowded and to allocate and assign parking spaces and
areas among Tenant and the other tenants of the Buildings, if any, and the
Property. Landlord shall not be liable to Tenant, nor shall this Lease be
affected, if any parking is impaired by moratorium, initiative, referendum, law,
ordinance, regulation or order passed, issued or made by any governmental or
quasi-governmental body or by fire or other casualty.

29.    Utilities and Services.
       ----------------------

  Tenant shall arrange for all telephone, water, gas, electricity, janitorial
services, and other power, utilities and services which it shall require in
connection with its use or occupancy of the Premises and shall pay for the same,
together with any taxes, penalties, surcharges or the like pertaining thereto.
In addition, Landlord shall have no obligation to furnish any utilities or
services to the Premises or any equipment providing for the same. Without
limitation, Tenant shall be solely responsible for providing such heating,
ventilation and air conditioning ("HVAC") to the Premises as Tenant shall
require for the comfortable occupancy thereof. Any equipment or systems which
Tenant shall require in order to supply HVAC shall be subject to the provisions
of Section 9 above. Tenant shall obtain, at its expense all electric light
bulbs, ballasts and tubes

                                      24
<PAGE>

as it shall require for the Premises. If any of the foregoing utilities or
services are not separately metered to Tenant, Tenant shall pay a reasonable
proportion, as determined by Landlord, of all charges jointly serving the
Premises and other premises. Landlord shall not be liable for any damages
directly or indirectly resulting from nor shall the Base Rent, Operating
Expenses or any other monies owed by Tenant to Landlord under this Lease be
abated or reduced by reason of (a) the installation, use or interruption of use
of any equipment used in connection with the furnishing of any of the foregoing
utilities and services, (b) failure to furnish or delay in furnishing any such
utilities or services for any reason whatsoever, or (c) the limitation,
curtailment, rationing or restriction on use of water, electricity, gas or any
other form of energy or any other service or utility whatsoever serving the
Premises or the Real Property. Landlord shall be entitled to cooperate
voluntarily and in a reasonable manner with the efforts of national, state or
local government agencies or utility suppliers in reducing energy or other
resource consumption. The obligation to make services available hereunder shall
be subject to the limitations of any such voluntary, reasonable program.

30.  Intentionally Deleted.
     ---------------------

31.  Acceptance.
     ----------

  Delivery of this Lease, duly executed by Tenant, constitutes Tenant's offer to
lease the Premises as set forth herein, and under no circumstances shall such
delivery be deemed to create an option or reservation to lease the Premises for
the benefit of Tenant. This Lease shall become effective and binding only upon
execution hereof by Landlord and delivery of a signed copy to Tenant. If
Landlord does not accept the Tenant's offer within twenty (20) days after the
date a copy of this Lease, as executed by Tenant, is received by Landlord,
Tenant's offer shall be deemed revoked and any sums delivered by Tenant with its
offer shall be returned to Tenant.

32.  Use of Building Name.
     --------------------

  Tenant shall not employ the name of either Building in the name or title of
its business or occupation, or for any other purpose, except to identify the
address of such Building (in Tenant's business cards, stationary or otherwise),
without Landlord's prior written consent, which consent Landlord may withhold in
its sole discretion. Landlord reserves the right, upon at least sixty (60) days'
prior written notice to Tenant, to change the name of each Building without
Tenant's consent and without any liability to Tenant.

33.  Recording.
     ---------

  Neither Landlord nor Tenant shall record this Lease, nor a short form
memorandum of this Lease, without the prior written consent of the other.

34.  Quitclaim.
     ---------

  Upon any termination or expiration of this Lease pursuant to its terms,
Tenant, at Landlord's request, shall execute, have acknowledged and deliver to
Landlord a quitclaim deed of all Tenant's interest in the Premises, Buildings
and Property created by this Lease.

35.  Notices.
     -------

  Any notice, demand or request required or desired to be given under this Lease
shall be in writing sent to the address of the party specified in this Lease,
and shall be given by hand delivery, electronic mail (e.g., telecopy), overnight
                                                      ---
courier service (e.g. Federal Express), or the United States mail, registered or
certified, the postage prepaid. All notices shall be deemed to have been given
when received at the address of the party

                                      25
<PAGE>

to which it has been sent (or when such receipt is refused). As of the date of
execution of this Lease, the addresses of Landlord and Tenant are as specified
in the Basic Lease Information. Either party may change its address by giving
notice of the change in accordance with this Section.

36.  Landlord's Exculpation.
     ----------------------

  The term "Landlord," as used in this Lease, shall mean only the owner or
owners of the Real Property at the time in question. Notwithstanding any other
provision of this Lease, the liability of Landlord for its obligations under
this Lease is limited solely to Landlord's interest in the Real Property as the
same may from time to time be encumbered, and no personal liability shall at any
time be asserted or enforceable against any other assets of Landlord or against
the constituent shareholders, partners or other owners of Landlord, or the
directors, officers, employees and agents of Landlord or such constituent
shareholder, partner or other owner, on account of any of Landlord's obligations
or actions under this Lease. Notwithstanding any other provision of this Lease,
Landlord shall not be liable for any consequential damages or interruption or
loss of business, income or profits, nor shall Landlord be liable for loss of or
damage to artwork, currency, jewelry, bullion, unique or valuable documents,
securities or other valuables, or for other property not in the nature of
ordinary fixtures, furnishings and equipment. Wherever in this Lease Tenant (a)
releases Landlord from any claim or liability, (b) waives or limits any right of
Tenant to assert any claim against Landlord or to seek recourse against any
property of Landlord or (c) agrees to indemnify Landlord against any matters,
the relevant release, waiver, limitation or indemnity shall run in favor of and
apply to Landlord, the constituent shareholders, partners or other owners of
Landlord, and the directors, officers, employees and agents of Landlord and each
such constituent shareholder, partner or other owner. In no event shall any
shareholder, partner, member, officer, director or other constituent of Landlord
or its direct or indirect constituents ever be personally liable for Landlord's
obligations or liability under this Lease.

37.  Additional Structures.
     ---------------------

  Any diminution or interference with light, air or view by any structure which
may be erected on land adjacent to the Buildings shall in no way alter this
Lease or impose any liability on Landlord.

38.  Consents and Approvals.
     ----------------------

  Wherever the consent, approval, judgment or determination of Landlord is
required or permitted under this Lease, except as expressly provided herein
Landlord may exercise its sole discretion in granting or withholding such
consent or approval or in making such judgment or determination. Whenever Tenant
requests Landlord to take any action or give any consent or approval, Tenant
shall reimburse Landlord for all of Landlord's costs incurred in reviewing the
proposed action or consent (whether or not Landlord consents to any such
proposed action), including, without limitation, reasonable attorneys' or
consultants' fees and expenses, within ten (10) days after Landlord's delivery
to Tenant of a statement of such costs. If it is determined that Landlord failed
to give its consent or approval where it was required to do so under this Lease,
Tenant's sole remedy will be an order of specific performance or mandatory
injunction of the Landlord's agreement to give its consent or approval. The
review and/or approval by Landlord of any item shall not impose upon Landlord
any liability for accuracy or sufficiency of any such item or the quality or
suitability of such item for its intended use. Any such review or approval is
for the sole purpose of protecting Landlord's interest in the Real Property, and
neither Tenant nor any Tenant Party nor any person or entity claiming by,
through or under Tenant, nor any other third party shall have any rights
hereunder by virtue of such review and/or approval by Landlord.

39.  General.
     -------

                                      26
<PAGE>

  a.  Captions. The captions and headings used in this Lease are for the
      --------
purpose of convenience only and shall not be construed to limit or extend the
meaning of any part of this Lease.

  b.  Time. Time is of the essence for the performance of each term, condition
      ----
and covenant of this Lease.

  c.  Severability. If any provision of this Lease is held to be invalid,
      ------------
illegal or unenforceable, the invalidity, illegality, or unenforceability shall
not affect any other provision of this Lease, but this Lease shall be construed
as if the invalid, illegal or unenforceable provision had not been contained
herein.

  d.  Choice of Law; Construction. This Lease shall be construed and enforced
      ---------------------------
in accordance with the laws of the State of California. The language in all
parts of this Lease shall in all cases be construed as a whole according to its
fair meaning and not strictly for or against either Landlord or Tenant.

  e.  Gender; Singular. Plural. When the context of this Lease requires, the
      ------------------------
neuter gender includes the masculine, the feminine, a partnership or corporation
or joint venture, and the singular includes the plural.

  f.  Binding Effect. The covenants and agreements contained in this Lease
      --------------
shall be binding on the parties hereto and, subject to Section 14 above, on
their respective successors and assigns.

  g.  Waiver. The waiver of either party of any breach of any term, condition
      ------
or covenant of this Lease shall not be deemed to be a waiver of the provision or
any subsequent breach of the same or any other term, condition or covenant of
this Lease. The subsequent acceptance of Rent hereunder by Landlord shall not be
deemed to be a waiver of any preceding breach at the time of acceptance of the
payment. No covenant, term or condition of this Lease shall be deemed to have
been waived unless the waiver is in writing signed by the party whose waiver is
sought.

  h.  Entire Agreement. This Lease is the entire agreement between the parties,
      ----------------
and supersedes all prior agreements, including letters of intent, between them,
and there are no agreements or representations between the parties except as
expressly set forth herein. Except as otherwise provided herein, no subsequent
change or addition to this Lease shall be binding unless in writing and signed
by the parties hereto.

  i.  Waiver of Jury. Tenant hereby waives any right it may have to a jury
      --------------
trial in the event of litigation between Tenant and Landlord pertaining to this
Lease. Landlord and Tenant agree that this paragraph constitutes a written
consent to waiver of trial by jury within the meaning of California Code of
Civil Procedure Section 631 (a)(2), and Tenant does hereby authorize and empower
Landlord to file this paragraph and or this Lease, as required, with the clerk
or judge of any court of competent jurisdiction as a written consent to waiver
of jury trial.

  j.  Counterparts. This Lease may be executed in counterparts, each of which
      ------------
shall be an original, and all of which together shall constitute but one
instrument.

  k.  Exhibits. The Basic Lease Information and all exhibits attached hereto are
      --------
hereby incorporated herein and made an integral part hereof.

  1.  Addendum. The Addendum, if any, attached hereto is hereby incorporated
      --------
herein and made an integral part hereof.

  m.  Other Leases. Tenant represents and warrants to Landlord that, with the
      ------------
exception of this Lease, neither Tenant nor any affiliate of Tenant is a tenant
under a lease or any other tenancy agreement (1) with

                                      27
<PAGE>

(a) Riggs & Company, a division of Riggs Bank N.A., as trustee of the Multi-
Employer Property Trust, (b) Riggs Bank N.A., as trustee of the Multi-Employer
Property Trust, (c) the Multi-Employer Property Trust, (d) the National Bank of
Washington Multi-Employer Property Trust, the previous name of the Multi-
Employer Property Trust, (e) The Riggs National Bank of Washington, D.C., as
trustee of the Multi-Employer Property Trust, (f) Northridge Business Center
LLC, (g) the Corporate Drive Corporation, as trustee of the Corporate Drive
Nominee Realty Trust, (h) Arboretum Lakes-I, L.L.C., a Delaware limited
liability company, (i) Village Green at Seven Bridges, L.L.C., (j) Pine Street
Development, L.L.C., (k) MEPT Realty LLC, a New York limited liability company,
(I) MEPT, L.L.C., a Delaware limited liability company, (m) Cabrillo Properties
LLC, (n) Valencia LLC, (o) Mission Trails LLC, or (p) Centrepointe Distribution
Center LLC, or (2) involving any property in which any one or more of the
entities named in clauses (1)(a) through (e) are known by Tenant to have an
ownership interest.

     IN WITNESS WHEREOF, the parties have executed this Lease on the dates set
forth below, effective as of the date first above written.

Landlord:                                          Tenant:

THE MULTI-EMPLOYER                                 AVANTGO, INC.,
PROPERTY TRUST, A TRUST                            a Delaware corporation
ORGANIZED UNDER 12 C.F.R.
SECTION 9.18, by its trustee
Riggs & Company, a division of                     By: /s/ [ILLEGIBLE]^^
                                                       -------------------------
Riggs Bank N.A.
                                                   Its: Chief Executive Officer
                                                        ------------------------

By: /s/ MaryAnne Martin                            By: /s/ Tom Hunter
   ------------------------------                     --------------------------
Its: Managing Director                             Its: CFO
     -----------------                                 -------------------------

                                      28
<PAGE>

                                   EXHIBIT A
                                   ---------

                                   PREMISES
                                   --------

                           [FLOOR PLAN APPEARS HERE]
<PAGE>

                                  EXHIBIT A-1
                                  -----------

                              PROPERTY SITE PLAN
                              ------------------

                           [FLOOR PLAN APPEARS HERE]
<PAGE>

                                   EXHIBIT B
                                   ---------

                              TENANT IMPROVEMENTS
                              -------------------

1.        Tenant Improvements.
          -------------------

          a.   Plans. Improvements shall be constructed in the Premises in
               -----
accordance with this Paragraph 1. Within fifteen (15) Business Days after the
date of the Lease, Tenant shall furnish to Landlord sufficient information (the
"Initial Information") so as to enable Landlord to prepare preliminary layout
plans and finish specifications for the Premises (the "Space Plans"). On the
basis of such information, Landlord shall furnish to Tenant for Tenant's written
approval (which shall not be unreasonably withheld) the Space Plans prepared by
Landlord's architect. Tenant shall respond to the Space Plans within three (3)
Business Days of its receipt thereof. Landlord shall respond within three (3)
Business Days to any reasonable objections of Tenant to the Space Plans and
shall resubmit to Tenant as soon as practicable for Tenant's approval (which
shall not be unreasonably withheld) appropriately revised Space Plans prepared
by Landlord's architect. Tenant shall respond to the revised Space Plans within
three (3) Business Days of its receipt thereof. This procedure shall be repeated
until the Space Plans are approved by Tenant. If Tenant fails to respond to the
Space Plans or the revised Space Plans within the periods described above,
Tenant shall be deemed to have approved the Space Plans or revised Space Plans,
as applicable. The Space Plans, as finally approved in writing by Landlord and
Tenant, shall be referred to herein as the "Final Space Plans." After completion
of the Final Space Plans, Landlord shall furnish to Tenant for Tenant's written
approval (which shall not be unreasonably withheld) working plans and
specifications (the "Working Drawings") for the Premises prepared by Landlord's
architect. Tenant shall respond to the Working Drawings within three (3)
Business Days of its receipt thereof. Landlord shall respond within three (3)
Business Days to any reasonable objections of Tenant to the Working Drawings and
shall resubmit to Tenant as soon as practicable for Tenant's approval (which
shall not be unreasonably withheld) appropriately revised Working Drawings
prepared by Landlord's architect. Tenant shall respond to the revised Working
Drawings within three (3) Business Days of its receipt thereof. This procedure
shall be repeated until the Working Drawings are approved by Tenant. If Tenant
fails to respond to the Working Drawings or the revised Working Drawings within
the periods described above, Tenant shall be deemed to have approved the Working
Drawings or revised Working Drawings, as applicable. The Working Drawings, as
approved in writing by Landlord and Tenant, as revised in accordance with the
following provisions of this Paragraph 1, are hereinafter called the "Final
Plans", and the improvements to be performed in accordance with the Final Plans
are hereinafter called the "Tenant Improvements". Any delay in Substantial
Completion of the Tenant Improvements or increased cost of the Tenant
Improvements caused directly or indirectly by any revision to the Space Plans or
the Working Drawings requested by Tenant or to otherwise make the same
acceptable to Tenant after the initial submission thereof to Tenant by Landlord,
shall constitute a Tenant Delay under Section 2 of the Lease; provided, however,
that as to the Space Plans only, Tenant shall be entitled to request revisions
to the initial submission thereof to Tenant, and to the first re-submission
thereof to Tenant, without the same giving rise to Tenant Delay. The parties
acknowledge that at Tenant's election, it may delay delivery to Landlord of the
Initial Information with respect to the Building E Premises until such date as
Tenant shall elect, rather than submitting the same to Landlord within the
fifteen (15) Business Day period first above referenced. In such event, the
procedures and other provisions of this Exhibit B shall be applied separately as
                                        ---------
to the Building E Premises and the Building F Premises and the respective Tenant
Improvements to be constructed therein.

          b.   Construction. Upon approval of the Final Plans. Landlord shall
               ------------
submit the same for pricing to a contractor selected by Landlord ("Landlord's
Contractor"), and thereafter provide Tenant with an

                                       1
<PAGE>

estimated budget for the Tenant Improvements, including Landlord's Construction
Operations Fee (as defined in Paragraph 1.f.iii.B. below). Tenant shall have
three (3) Business Days after the receipt of Landlord's estimated budget to
approve or reasonably disapprove of the same. If Tenant disapproves of the
budget within such three (3) Business Day period, Tenant shall so notify
Landlord and the Final Plans shall promptly be modified by Landlord's architect
in order to satisfactorily reduce the amount of the estimated budget, as
requested by Tenant. Any and all revisions to the Final Plans shall be subject
to Landlord's and Tenant's reasonable approval. Upon Landlord's revision of the
Final Plans, Landlord shall cause Landlord's Contractor to promptly issue new
pricing and upon receipt of such pricing Landlord shall prepare and submit to
Tenant a revised estimated budget. Tenant shall respond to the revised estimated
budget in the manner described above. Any delay in Substantial Completion of the
Tenant Improvements or increased cost of the Tenant Improvements caused directly
or indirectly by any revision to the Final Plans or the estimated budget to
address Tenant's disapproval of the estimated budget shall constitute a Tenant
Delay under Section 2 of the Lease. If Tenant fails to raise any objections to
the budget within the three (3) Business Day period(s) described above, Tenant
shall be deemed to have approved Landlord's proposed budget. Landlord shall
commence construction of the Tenant Improvements promptly after approval of the
Final Plans, and thereafter diligently pursue such construction to completion
(but in no event shall Landlord be required to pursue a construction schedule
which would cause Substantial Completion to occur prior to August 1, 200O).
Landlord shall use reasonable care in preparing the budget, but it shall be a
good faith estimate only and will not limit Tenant's obligation to pay for its
share of the costs of the Tenant Improvements as set forth below in this
Paragraph I.

          c.   Changes. In the event that Tenant shall request any change in or
               -------
to the Final Plans (a "Change"), Landlord's architect shall prepare for
Landlord's and Tenant's review and written approval a change order with respect
to such Change (the "Change Order"), together with, if appropriate, revised
Working Drawings incorporating the requested Change and clearly identifying the
same as such on the revised Working Drawings. Landlord shall not unreasonably
withhold or delay its approval of the Change Order or revised Working Drawings,
provided, however, that Landlord shall have at least three (3) Business Days
after receipt thereof to review any proposed Change. In the event that Landlord
shall approve any proposed Change, together with such approval, if practicable,
and if not practicable as soon thereafter as is practicable, Landlord shall give
Tenant Landlord's estimated increase or decrease in the cost of the Tenant
Improvements which would result from incorporating such Change and Landlord's
estimate of the delay, if any, in the commencement or completion of the Tenant
Improvements which would result from incorporating such Change. Landlord will
use reasonable care in preparing the estimates, but they shall be good faith
estimates only and will not limit Tenant's obligation to pay for the actual
increase in the cost of the Tenant Improvements or Tenant's responsibility for
the actual construction delay resulting from the Change. Within three (3)
Business Days after receipt of such cost and delay estimates, Tenant shall
notify Landlord in writing whether Tenant approves the Change. If Tenant fails
to approve the change within such three (3) Business Day period, construction of
the Tenant Improvements shall proceed as provided in accordance with the Final
Plans as they existed prior to the requested Change. If, following Tenant's
review of the estimated costs and delays, Tenant desires Landlord to incorporate
the Change into the Tenant Improvements, then Tenant and Landlord shall execute
a change order for such Change on Landlord's standard form therefor, and the
term "Final Plans" shall thereafter be deemed to refer to the Working Drawings
as so revised and approved.

          d.   Intentionally Deleted.
               ---------------------

          e.   Intentionally Deleted.
               ---------------------

          f.   Cost of Improvements.  The cost of the construction and
               --------------------
installation of the Tenant

                                       2
<PAGE>

Improvements shall be borne as follows:

                    i.   Intentionally Deleted.

                    ii.  Landlord's architectural, engineering and other
              consultant fees in connection with the design and construction of
              the Tenant Improvements, including the costs of producing the
              Space Plans, Final Space Plans, Working Drawings and Final Plans,
              shall be paid by Tenant upon Landlord's demand, subject to
              Tenant's right to use a portion of Landlord's Contribution towards
              the amount of such costs as provided below.

                    iii. Landlord shall contribute toward the cost of the
               construction and installation of the Tenant Improvements an
               amount not to exceed $2,157,600.00 (which is the product of
               $25.00 times the stipulated number of rentable square feet of the
               Premises as set forth in the Basic Lease Information)
               ("Landlord's Contribution"). Landlord's Contribution shall be
               allocated $923,300.00 to the Building E Premises and
               $1,286,225.00 to the Building F Premises. The following
               provisions shall govern the payment of Landlord's Contribution:

                         A.   Excess Cost; Share of Costs. If the total cost of
                              ---------------------------
               construction of the Tenant Improvements (including, without
               limitation, the Construction Operations Fee described below, and
               all architectural, engineering and permits fees and taxes)
               exceeds the funds available therefor from Landlord's
               Contribution, then Tenant shall pay all such excess (the "Excess
               Cost"). Based on the estimated cost (the "Estimated Costs") of
               the construction of the Tenant Improvements, the prorata share of
               the Estimated Costs payable by Landlord and Tenant shall be
               determined and an appropriate percentage share established for
               each (a "Share of Costs"). Tenant and Landlord shall fund the
               cost of such work as the same is performed, in accordance with
               their respective Share of Costs for such work. At such time as
               Landlord's Contribution has been entirely disbursed, Tenant shall
               pay the remaining Excess Cost, if any, which payments shall be
               made in installments as construction progresses in the same
               manner as Tenant's payments of Tenant's Share of Costs were paid.

                         B.   Construction Operations Fee. Landlord shall retain
                              ---------------------------
               from the amount of Landlord's Contribution, in the manner
               described below, an aggregate sum equal to four percent (4%) of
               the total cost of the construction and installation of the Tenant
               Improvements (which cost of the construction and installation,
               for purposes of this paragraph B, shall include architectural and
               engineering fees but shall not include permit fees) (the
               "Construction Operations Fee") as compensation to Landlord for
               review of plans, specifications and budgets, coordinating the
               schedule for construction of the Tenant Improvements, and for
               other miscellaneous costs incurred by Landlord as a result of the
               construction work. At the time Landlord makes any disbursement of
               Landlord's Contribution, Landlord shall retain from Landlord's
               Contribution, as a partial payment of the Construction Operations
               Fee, a proportionate amount of the Construction Operations Fee
               based upon Landlord's reasonable estimate of the amount required
               to be withheld from such disbursement in order to ensure that the
               entire Construction Operations Fee is retained over the course of
               construction on a prorata basis. At such time as Landlord's
               Contribution has been entirely disbursed, if the entire
               Construction Operations Fee has not yet been paid to Landlord,
               Tenant shall pay to Landlord a prorata portion of each payment
               made by Tenant on account of the Tenant Improvements in order to
               ensure that the balance of the Construction Operations Fee is
               paid to Landlord over the course of construction

                                       3
<PAGE>

               on a prorata basis.

                         C.   Certain Limitations. In no event may any portion
                              -------------------
               of Landlord's Contribution be applied towards the costs of
               Tenant's architectural or engineering fees (if any), trade
               fixtures, personal property, equipment or furniture,
               telecommunications cabling, or towards rent due under this Lease.
               Notwithstanding anything to the contrary in this Exhibit B of the
                                                                ---------
               Lease, Landlord's Contribution shall be available for
               disbursement pursuant to the terms hereof only for the first
               twelve (12) months after the Date of this Lease. Accordingly, if
               any portion of Landlord's Contribution is not utilized prior to
               the date that is twelve (12) months from the Commencement Date,
               such unused portion shall be forfeited by Tenant.

                         D.   Entire Premises to be Improved. Tenant
                              ------------------------------
               acknowledges that Landlord's Contribution is to be applied to the
               Tenant Improvements covering the entire Premises. If Tenant does
               not improve the entire Premises, then, without limitation of any
               other rights or remedies of Landlord hereunder, Landlord's
               Contribution shall be adjusted on a prorata per rentable square
               foot basis to reflect the number of rentable square feet actually
               being improved.

                                       4
<PAGE>

                                   EXHIBIT C
                                   ---------

                         COMMENCEMENT DATE MEMORANDUM
                         ----------------------------

LANDLORD: _____________________________
          _____________________________

TENANT:   _____________________________
          _____________________________

LEASE DATE:____________________________

PREMISES:  ____________________________
           ____________________________
           ____________________________

Pursuant to Section 2.d. of the above-referenced Lease, the Commencement Date of
the Lease is hereby established as __________, and the Expiration Date of the
Lease is hereby established as ____________.

           LANDLORD:

           ___________________________
           a__________________________

           By_________________________
             Its______________________

           TENANT:

           ___________________________
           a__________________________

           By_________________________
             Its______________________
<PAGE>

                                   EXHIBIT D
                                   ---------

                             RULES AND REGULATIONS
                             ---------------------

1.   No sign, placard, picture, advertisement, name or notice shall be installed
or displayed on any part of the outside or inside of the Building without the
prior written consent of Landlord. Landlord shall have the right to remove, at
Tenant's expense and without notice, any sign installed or displayed in
violation of this rule. All approved signs or lettering on doors, windows and
walls shall1 be printed, painted, affixed or inscribed at the expense of Tenant
by a person chosen by Landlord, using materials of Landlord's choice and in a
style and format approved by Landlord.

2.   The directory of the Building will be provided exclusively for the display
of the name and location of tenants, and Landlord reserves the right to exclude
any other names therefrom. Tenant shall pay Landlord's standard charge for
Tenant's listing thereon and for any changes by Tenant.

3.   Except as consented to in writing by Landlord or in accordance with
Building standard improvements, no draperies, curtains, blinds, shades, screens
or other devices shall be hung at or used in connection with any window or
exterior door or doors of the Premises. No awning shall be permitted on any part
of the Premises. Tenant shall not place anything against or near glass
partitions or doors or windows which may appear unsightly from outside the
Premises.

4.   Tenant shall not obstruct any sidewalks, halls, lobbies, passages, exits,
entrances, elevators or stairways of the Building. No tenant and no employee or
invitee of any tenant shall go upon the roof of the Building or make any roof or
terrace penetrations. Tenant shall not allow anything to be placed on the
outside terraces or balconies without the prior written consent of Landlord.

5.   No Tenant shall invite to the Premises, or permit the visit of, persons in
such numbers or under such conditions as to interfere with the use and enjoyment
of the Common Areas of the Building by other tenants.

6.   No person or persons other than those approved by Landlord, such approval
not to be unreasonably withheld, shall be employed by Tenant or permitted to
enter the Building for the purpose of cleaning. Tenant shall not cause any
unnecessary labor by carelessness or indifference to the good order and
cleanliness of the Premises. Landlord shall not in any way be responsible to any
Tenant for any loss of property on the Premises, however occurring, or for any
damage to any Tenant's property by the janitor or any other employee or person.

7.   Landlord will furnish Tenant, free of charge, one hundred (100) keys to
Tenant's suite entrance. Landlord may make a reasonable charge for any
additional keys and for having any locks changed. Tenant shall not alter any
lock or install a new additional lock or bolt on any door of its Premises unless
Tenant shall give Landlord a key thereto. Tenant shall deliver to Landlord, upon
the termination of its tenancy, the keys to all locks for doors on the Premises.
If Tenant loses any keys furnished by Landlord, Tenant shall pay Landlord the
cost of rekeying the Premises.

   Landlord will furnish Tenant, free of charge, two (2) building access cards.
A reasonable charge will be assessed for any additional cards and lost or stolen
cards. Tenant shall deliver to Landlord, upon the termination of its tenancy,
all access cards.

8.   If Tenant requires telegraphic, telephonic, burglar alarm or similar
services, it shall first obtain, and comply with, Landlord's instructions for
their installation.

                                       1
<PAGE>

9.   The elevator shall be available for use by all tenants in the Building,
subject to reasonable scheduling as Landlord in its discretion shall deem
appropriate. No equipment, materials, furniture, packages, supplies, merchandise
or other property will be received in the Building or carried in the elevator
except between the hours, in the manner and in the elevators as may be
designated by Landlord.

10.  Tenant shall not place a load upon any floor of the Premises which exceeds
the maximum load per square foot which the floor was designed to carry and which
is allowed by law. Tenant's business machines and mechanical equipment which
cause noise or vibration which may be transmitted to the structure of the
Building or to any space therein, and which is objectionable to Landlord or to
any tenants in the Building, shall be placed and maintained by Tenant, at
Tenant's expense, on vibration eliminators or other devices sufficient to
eliminate noise or vibration.

11.  Tenant shall not use or keep in the Premises any toxic or hazardous
materials or any kerosene, gasoline or inflammable or combustible fluid or
material other than those limited quantities necessary for the operation or
maintenance of office equipment. Tenant shall not use or permit to be used in
the Premises any foul or noxious gas or substance, or permit or allow the
Premises to be occupied or used in a manner offensive or objectionable to
Landlord or other occupants of the Building by reason of noise, odors or
vibrations. No animal, except seeing eye dogs when in the company of their
masters, may be brought into or kept in the Building.

     Notwithstanding the foregoing, with Landlord's prior written consent, which
shall not be unreasonably withheld, Tenant shall be permitted to bring dogs into
the Premises, provided all such dogs are well behaved, and do not present a
threat of personal injury or property damage to the Building or Property. Tenant
shall ensure that any dog waste in or about the Building or the Property is
promptly picked-up and properly disposed of as reasonably required by Landlord,
all at Tenant's sole cost and expense. In the event that any dogs permitted in
the Premises pursuant to the foregoing are determined by Landlord, in good
faith, to present risk of personal injury or property damage to the Building or
the Property, Landlord may revoke its consent with respect to any such dog or
dogs and Tenant shall immediately remove the same from the Premises and the
Property. Tenant's indemnity pursuant to Section 13 of the Lease shall fully
apply to any dogs of Tenant or any Tenant Party, and any Claims in connection
therewith.

12.  Tenant shall not use any method of heating or air-conditioning other than
that supplied by Landlord, unless Tenant receives the prior written consent of
Landlord.

13.  Tenant shall cooperate fully with Landlord to assure the most effective
operation of the Building's heating and air-conditioning and to comply with any
governmental energy-saving rules, laws or regulations of which Tenant has actual
notice. Tenant shall refrain from attempting to adjust controls other than room
thermostats installed for Tenant's use.

14.  All entrance doors to the Premises shall be left locked when the Premises
are not in use, and all doors opening to public corridors shall be kept closed
except for normal ingress and egress to and from the Premises.

15.  Landlord reserves the right, exercisable with at least sixty (60) days'
prior written notice to Tenant, and without liability to Tenant, to change the
name and street address of the Building.

16.  Landlord reserves the right to prevent access to the Building by closing
the doors or by other appropriate action in case of invasion, mob, riot, public
excitement or other commotion.

17. Tenant shall close and lock the doors of its Premises, shut off all water
faucets or other water apparatus and turn off all lights and other equipment
which is not required to be continuously run. Tenant shall be responsible for
any damage or injuries sustained by other tenants or occupants of the Building
or

                                       2
<PAGE>

Landlord for noncompliance with this Rule.

18.  The toilet rooms, toilets, urinals, wash bowls and other apparatus shall
not be used for any purpose other than that for which they were constructed, and
no foreign substance of any kind whatsoever shall be placed therein. The expense
of any breakage, stoppage or damage resulting from any violation of this rule
shall be borne by the tenant who, or whose employees or invitees, shall have
caused it.

19.  Tenant shall not install any radio or television antenna, loudspeaker or
other device on the roof or exterior walls of the Building. Tenant shall not
interfere with radio or television broadcasting or reception from or in the
Building or elsewhere.

20.  Tenant shall not cut or bore holes for wires in the partitions, woodwork or
plaster of the Premises. Tenant shall repair, or be responsible for the cost of
repair of any damage resulting from noncompliance with this Rule.

21.  Tenant shall not install, maintain or operate upon the Premises any vending
machine (other than vending machines for use by Tenant's employees) without the
prior written consent of Landlord.

22.  Canvassing, soliciting and distributing handbills or any other written
material and peddling in the Building are prohibited, and each tenant shall
cooperate to prevent these activities.

23.  Landlord reserves the right to exclude or expel from the Building any
person who, in Landlord's judgment, is intoxicated or under the influence of
liquor or drugs, or who is in violation of any of the Rules and Regulations of
the Building.

24.  Tenant shall store all its trash and garbage within its Premises. Tenant
shall not place in any trash box or receptacle any material which cannot be
disposed of in the ordinary and customary manner of trash and garbage disposal
within the Building. All garbage and refuse disposal shall be made in accordance
with directions issued from time to time by Landlord.

25.  Use by Tenant of Underwriters' Laboratory approved equipment for brewing
coffee, tea, hot chocolate and similar beverages and microwaving food shall be
permitted, provided that the equipment and use is in accordance with all
applicable federal, state, county and city laws, codes, ordinances, rules and
regulations.

26.  Tenant shall not use the name of the Building in connection with or in
promoting or advertising the business of Tenant, except as Tenant's address,
without the written consent of Landlord.

27.  Tenant shall comply with al1 safety, fire protection and evacuation
procedures and regulations established by Landlord or any governmental agency.
Tenant shall be responsible for any increased insurance premiums attributable to
Tenant's use of the Premises, Building or Property.

28.  Tenant assumes any and all responsibility for protecting its Premises from
theft and robbery, which responsibility includes keeping doors locked and other
means of entry to the Premises closed.

29.  Tenant shall not use the Premises, or suffer or permit anything to be done
on, in or about the Premises, which may result in an increase to Landlord in the
cost of insurance maintained by Landlord on the Building and Common Areas.

30.  Tenant's requests for assistance will be attended to only upon appropriate
application to the office of the Building by an authorized individual. Employees
of Landlord shall not perform any work or do anything outside of their regular
duties unless under special instructions from Landlord, and no employee

                                       3
<PAGE>

of Landlord will admit any person (Tenant or otherwise) to any office without
speci
fic instructions from Landlord.

31.  Tenant shall not park its vehicles in any parking areas designated by
Landlord as areas for parking by visitors to the Building or other reserved
parking spaces. Tenant shall not leave vehicles in the Building parking areas
overnight, nor park any vehicles in the Building parking areas other than
automobiles, motorcycles, motor driven or non-motor driven bicycles or four-
wheeled trucks. Tenant, its agents, employees and invitees shall not park any
one (1) vehicle in more than one (1) parking space.

32.  Landlord shall have the right to approve or disapprove the movers or moving
company employed by Tenant, which approval shall not be unreasonably withheld.
If Tenant's movers damage any part of the Property, Tenant shall pay to Landlord
the amount required to repair the damage.

33.  No cooking shall be permitted on the Premises, except with a microwave
oven, nor shall the Premises be used for the storage of merchandise, for washing
clothes, for lodging or for any improper, objectionable or immoral purpose.

34.  Tenant shall not use in any space or in the public halls of the Building,
any hand trucks except those equipped with rubber tires and side guards or such
other material-handling equipment as Landlord may approve. Tenant shall not
bring any bicycles or other vehicles of any kind into the building.

35.  Landlord shall have the right to control and operate the public portions of
the Building, and the public facilities, heating and air conditioning, as well
as facilities furnished for the common use of the tenants, in such manner as it
deems best for the benefit of the tenants generally.

36.  Landlord may waive any one or more of these Rules and Regulations for the
benefit of Tenant or any other tenant, but no waiver by Landlord shall be
construed as a waiver of the Rules and Regulations in favor of Tenant or any
other tenant, nor prevent Landlord from thereafter enforcing the Rules and
Regulations against any or all of the tenants of the Building.

37.  These Rules and Regulations are in addition to, and shall not be construed
to in any way modify or amend, in whole or in part, the terms, covenants,
agreements and conditions of any lease of premises in the Building.

38.  Landlord reserves the right to make other reasonable Rules and Regulations
as, in its judgment, may from time to time be needed for safety and security,
for care and cleanliness of the Building and for the preservation of good order
therein. Tenant agrees to abide by all Rules and Regulations hereinabove stated
and any additional rules and regulations which are adopted.

39.  Tenant shall be responsible for the observance of all of the foregoing
rules by Tenant's employees, agents, clients, customers, invitees and guests.

40.  As used in these Rules and Regulations, the term "Building" shall mean all
buildings in which any portion of the Premises is located.

                                       4
<PAGE>

                                   EXHIBIT E
                                   ---------

                          Tenant Estoppel Certificate
                          ---------------------------

TO:  The Multi-Employer Property Trust, a trust organized under 12 C.F.R.
     Section 9.18 ("Landlord")

               c/o Kennedy Associates Real Estate Counsel, Inc.
               2400 Financial Center Building
               1215 Fourth Avenue
               Seattle, Washington 98161

 THIS IS TO CERTIFY:

          1.   That the undersigned is the Tenant under that certain Lease
dated, ________________, and, if applicable, amended on _____________, by and
between The Multi-Employer Property Trust by its trustee Riggs & Company, a
division of Riggs Bank N.A. ("Landlord"), and the undersigned ("Tenant")
covering those certain premises located as shown on the drawing made part of the
Lease (the "Premises").

         2.    That said Lease is in full force and effect and, except as noted
 in paragraph 1 above, has not been modified, changed, altered or amended in any
 respect, and is the only lease or agreement between the Tenant and the Landlord
 affecting the Premises.

         3.    To the best of Tenant's knowledge, the information set forth
below is true and correct:

               3.1    Square footage of the Premises:_________________________

               3.2    Annual rent as of the commencement of Lease:$___________

               3.3    Current annual rent (if different than at
                      commencement):$_________________________________________

               3.4    Commencement date of Lease:_____________________________

               3.5    Lease termination date:_________________________________

               3.6    Rent paid to and including:_____________________________

               3.7    Security deposit:_______________________________________

               3.8    Prepaid rent for and in amount of:$_____________________

               3.9    Free Rent Period:__________________ to _________________

               3.10   Amount of current monthly escrow payment obligations with

                      respect to taxes, insurance, and Common Area Maintenance

                      charges under the Lease:

                           Taxes:                                $____________

                           Insurance:                            $____________

                           Common Area Maintenance Charges:      $____________
<PAGE>

           3.11 Dates through which Tenant has paid monthly escrow payments and
                Common Area Maintenance charges:

                    Escrow Payment for Taxes:                    ____________

                    Escrow Payment for Insurance:                ____________

                    Common Area Maintenance charge:              ____________

           3.12 Base Amounts (stops) established in leases for monthly escrow
                payments:

                    Base Amount Taxes:                         $ ____________

                    Base Amount Insurance:                     $ ____________

                    Base Amount Maintenance Charge:            $ ____________

     4.   Tenant now occupies the Premises, accepts the Premises in their
current condition subject only to those punch list items listed in Exhibit A, if
                                                                   ---------
any, and is not aware of any defect in the Premises except as described in
Exhibit A, if any.
---------

     5.   No rent has been paid in the current month other than as disclosed in
paragraph 3. No free rent or other concessions, benefits, or inducements other
than as specified in the Lease have been granted to Tenant or undertaken by the
Landlord.

     6.   Tenant has not been granted any renewal, expansion or purchase options
and has not been granted any rights of first refusal except as disclosed In
writing in the Lease.

     7.   Neither Tenant nor to the best of Tenant's knowledge, Landlord is in
breach of the Lease and there has not occurred any event, act, omission or
condition which by notice or lapse of time or both or otherwise, will result in
any breach by Tenant or to the best of Tenant's knowledge, by Landlord. As of
the date hereof, and except as set forth in the Lease, the undersigned is
entitled to no credit, offset or deduction in rent. Tenant knows of no
liabilities or obligations of Landlord which have accrued but are unsatisfied
under the Lease as of the date of this Certificate.

     8.   To the best of Tenant's knowledge, there are no actions, whether
voluntary or otherwise, pending against the undersigned under the bankruptcy
laws or other laws for the relief of debtors of the United States or any state
thereof.

     9.   With the exception of this Lease, neither the Tenant nor any affiliate
of the Tenant is a tenant under a lease or any other tenancy arrangement (1)
with (a) Riggs & Company, a division of Riggs Bank N.A., as trustee of the
Multi-Employer Property Trust; (b) Riggs Bank N.A., as trustee of the
Multi-Employer Property Trust, (c) the Multi-Employer Property Trust; (d) the
National Bank of Washington Multi-Employer Property Trust, the previous name of
the Multi-Employer Property Trust; (e) The Riggs National Bank of Washington,
D.C., as trustee of the Multi-Employer Property Trust; (f) the Corporate Drive
Corporation as trustee of the Corporate Drive Nominee Realty Trust; (g)

                                      -2-
<PAGE>

Arboretum Lakes-1, L.L.C., a Delaware limited liability company; (h) Village
Green at Seven Bridges, L.L.C.; (i) Pine Street Development, L.L.C.; (j) MEPT
Realty LLC; (k) MEPT, L.L.C.; (l) Cabrillo Properties LLC; (m) Valencia LLC; (n)
Centrepointe Distribution Center LLC; (o) Mission Trails LLC; or (p) Northridge
Business Center LLC; or (2) involving any property in which any one or more of
the entities named in clauses (1) (a) through (e) are known by the Tenant to
have an ownership Interest. [This paragraph will be updated from time to time.]

         DATED this_________day of_____________________, 19 __.

                                                  TENANT:

                                                  ___________________________
                                                  a__________________________

                                                  By:________________________
                                                       Name:_________________
                                                       Its:__________________

                                      -3-
<PAGE>

                   EXHIBIT A to Tenant Estoppel Certificate

                                List of Defects
                                ---------------

                                     -4-

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