Document:

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                                  US BANK PLAZA
                              BELLEVUE, WASHINGTON

                             OFFICE LEASE AGREEMENT

                                     BETWEEN

                       EOP OPERATING LIMITED PARTNERSHIP,
                         A DELAWARE LIMITED PARTNERSHIP
                                  ("LANDLORD")

                                       AND

                               LIGHTBRIDGE, INC.,
                             A DELAWARE CORPORATION
                                   ("TENANT")

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                             OFFICE LEASE AGREEMENT

      THIS OFFICE LEASE AGREEMENT (the "LEASE") is made and entered into as of
the 10th day of August, 2004, by and between EOP OPERATING LIMITED PARTNERSHIP,
A DELAWARE LIMITED PARTNERSHIP ("LANDLORD") and LIGHTBRIDGE, INC., A DELAWARE
CORPORATION ("TENANT"). The following exhibits and attachments are incorporated
into and made a part of this Lease: EXHIBIT A (Outline and Location of
Premises), EXHIBIT A-1 (Outline and Location of Must Take Space), EXHIBIT A-2
(Legal Description), EXHIBIT B (Expenses and Taxes), EXHIBIT C (Work Letter),
EXHIBIT C-1 (Must Take Space Work Letter), EXHIBIT D (Commencement Letter),
EXHIBIT E (Building Rules and Regulations), EXHIBIT F (Additional Provisions)
and EXHIBIT G (Janitorial Specifications).

1. BASIC LEASE INFORMATION.

      1.01  "BUILDING" shall mean the building located at 10800 NE 8th Street,
            Bellevue, Washington, commonly known as US Bank Plaza. "RENTABLE
            SQUARE FOOTAGE OF THE BUILDING" is deemed to be 137,373 square feet.

      1.02  "PREMISES" shall mean the area shown on EXHIBIT A-1 to this Lease.
            The Premises is located on the 6th floor and known as suite 600. If
            the Premises include one or more floors in their entirety, all
            corridors and restroom facilities located on such full floor(s)
            shall be considered part of the Premises. The "RENTABLE SQUARE
            FOOTAGE OF THE PREMISES" is deemed to be 14,148 square feet.
            Landlord and Tenant stipulate and agree that the Rentable Square
            Footage of the Building and the Rentable Square Footage of the
            Premises are correct.

      1.03  "BASE RENT":

<TABLE>
<CAPTION>
                             ANNUAL RATE        MONTHLY
     MONTHS OF TERM        PER SQUARE FOOT     BASE RENT
-----------------------    ---------------    ----------
<S>                        <C>                <C>
   Commencement Date
    through 9/30/05            $11.75         $13,853.25
10/1/05 through 9/30/06        $12.25         $14,442.75
10/1/06 through 9/30/07        $12.75         $15,032.25
10/1/07 through 9/30/08        $13.25         $15,621.75
10/1/08 through 9/30/09        $13.75         $16,211.25
</TABLE>

                  Notwithstanding anything in this Section 1.03 to the contrary,
            so long as Tenant is not in default under this Lease, Tenant shall
            be entitled to an abatement of Rent (Base Rent and Additional Rent)
            in the approximate amount of $23,297.04 per month (i.e. $13,853.25
            in Base Rent and approximately $9,443.79 in Additional Rent) for the
            first 3 consecutive full calendar months of the Term (the "RENT
            ABATEMENT PERIOD"). The total amount of Rent abated during the Rent
            Abatement Period shall equal approximately $69,891.12 (the "ABATED
            RENT"). If Tenant defaults at any time during the Term and fails to
            cure such default within any applicable cure period under the Lease,
            all unamortized Abated Rent (i.e. based upon the amortization of the
            Abated Rent in equal monthly amounts during the initial Term,
            without interest) shall immediately become due and payable. The
            payment by Tenant of the Abated Rent in the event of a default shall
            not limit or affect any of Landlord's other rights, pursuant to this
            Lease or at law or in equity. During the Rent Abatement Period, only
            Base Rent and Tenant's Pro Rata Share of Expenses and Taxes shall be
            abated and any other costs and charges specified in this Lease shall
            remain as due and payable pursuant to the provisions of this Lease.

      1.04  "TENANT'S PRO RATA SHARE": 10.2990% (subject to Section I.B.2 of
            EXHIBIT F).

      1.05  "BASE YEAR" [INTENTIONALLY OMITTED]

      1.06  "TERM": A period of 60 months and any partial month at the beginning
            of the Term. Subject to Section 3, the Term shall commence on
            September 15, 2004 (the "COMMENCEMENT DATE") and, unless terminated
            early in accordance with this Lease, end on September 30, 2009 (the
            "TERMINATION Date").

      1.07  Allowance(s): $52,607.87 (i.e., $10.63 multiplied by the Rentable
            Square Footage of the Must-Take Space) towards the cost of Initial
            Alterations (defined in EXHIBIT C-1) to the Must Take Space, as
            further described in EXHIBIT C-1 (Must Take Space Work Letter). In
            addition, as further described in the Work Letter attached hereto as
            EXHIBIT C, Landlord shall perform work in the Premises up to a
            maximum amount of $176,850.00, as provided in EXHIBIT C.

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      1.08  "SECURITY DEPOSIT": $31,325.34, as more fully described in Section
            6.

      1.09  "GUARANTOR(S)": As of the date of this Lease, there are no
            Guarantors.

      1.10  "BROKER(S)": Colliers International ("TENANT'S BROKER"), which
            represented Tenant in connection with this transaction, and Equity
            Office Properties Management Corp. ("LANDLORD'S BROKER"), which
            represented Landlord in connection with this transaction.

      1.11  "PERMITTED USE": General office use.

      1.12  "NOTICE ADDRESS(ES)":

<TABLE>
<CAPTION>
Landlord:                                  Tenant:
<S>                                        <C>
EOP Operating Limited Partnership
c/o Equity Office Management, L.L.C.       Lightbridge, Inc.
701 5th Avenue                             30 Corporate Drive
Suite 4000                                 Burlington, Massachusetts  01803
Seattle, Washington 98104                  Attn:  President
Attn:  Property Manager, US Bank Plaza
</TABLE>

            A copy of any notices to Landlord shall be sent to Equity Office,
            One Market, Spear Tower, Suite 600, San Francisco, California 94105,
            Attn: Seattle Regional Counsel. A copy of any default notices to
            Tenant shall be sent to Foley Hoag LLP, 155 Seaport Boulevard,
            Boston, Massachusetts 02210, Attn: John D. Patterson, Jr., Esq.

      1.13  "BUSINESS DAY(S)" are Monday through Friday of each week, exclusive
            of New Year's Day, Presidents Day, Memorial Day, Independence Day,
            Labor Day, Thanksgiving Day and Christmas Day ("HOLIDAYS"). Landlord
            may designate additional Holidays that are commonly recognized by
            other office buildings in the area where the Building is located.
            "BUILDING SERVICE HOURS" are 6:00 A.M. to 7:00 P.M. on Business Days
            and 9:00 A.M. to 1:00 P.M. on Saturdays.

      1.14  "LANDLORD WORK" means the work that Landlord is obligated to perform
            in the Premises pursuant to a separate agreement (the "WORK LETTER")
            attached to this Lease as EXHIBIT C.

      1.15  "PROPERTY" means the Building and the parcel(s) of land on which it
            is located and, at Landlord's discretion, the parking facilities and
            other improvements, if any, serving the Building and the parcel(s)
            of land on which they are located.

2. LEASE GRANT.

      The Premises are hereby leased to Tenant from Landlord, together with the
right to use any portions of the Property that are designated by Landlord for
the common use of tenants and others (the "COMMON AREAS").

3. ADJUSTMENT OF COMMENCEMENT DATE; POSSESSION.

      3.01 If Landlord is required to perform Landlord Work prior to the
Commencement Date: (a) the date set forth in Section 1.06 as the Commencement
Date shall instead be defined as the "TARGET COMMENCEMENT DATE"; (b) the actual
Commencement Date shall be the date on which Landlord tenders delivery of the
Premises to Tenant with the Landlord Work Substantially Complete (defined
below); and (c) the Termination Date will be the last day of the Term as
determined based upon the actual Commencement Date. Landlord's failure to
Substantially Complete the Landlord Work by the Target Commencement Date shall
not be a default by Landlord or otherwise render Landlord liable for damages.
Promptly after the determination of the Commencement Date, Landlord and Tenant
shall enter into a commencement letter agreement in the form attached as EXHIBIT
D. The Landlord Work shall be deemed to be "SUBSTANTIALLY COMPLETE" on the date
that all Landlord Work has been performed, other than any details of
construction, mechanical adjustment or any other similar matter, the
non-completion of which does not materially interfere with Tenant's use of the
Premises. If Landlord is delayed in the performance of the Landlord Work as a
result of the acts or omissions of Tenant, the Tenant Related Parties (defined
in Section 13) or their respective contractors or vendors, including, without
limitation, changes requested by Tenant to approved plans, Tenant's failure to
comply with any of its obligations under this Lease, or the specification of any
materials or equipment with long lead times (a "TENANT DELAY"), the Landlord
Work shall be deemed to be Substantially Complete on the date that Landlord
could reasonably have been expected to Substantially Complete the Landlord Work
absent any Tenant Delay. Landlord shall use reasonable efforts to notify Tenant,
orally or in writing, of any

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circumstances of which Landlord is aware that have caused or may cause a Tenant
Delay, so that Tenant may take whatever action is appropriate to minimize or
prevent such Tenant Delay.

      3.02 Notwithstanding the foregoing, if the actual Commencement Date has
not occurred on or before the Required Completion Date (defined below), Tenant,
as its sole remedy, may terminate this Lease by giving Landlord written notice
of termination on or before the earlier to occur of: (i) 5 Business Days after
the Required Completion Date; and (ii) the actual Commencement Date. In such
event, this Lease shall be deemed null and void and of no further force and
effect and Landlord shall promptly refund any prepaid rent and Security Deposit
previously advanced by Tenant under this Lease and, so long as Tenant has not
previously defaulted under any of its obligations under the Work Letter, the
parties hereto shall have no further responsibilities or obligations to each
other with respect to this Lease. The "REQUIRED COMPLETION DATE" shall mean the
later to occur of (a) the date which is 60 days after the date the building
permit for the Landlord Work has been obtained, and (b) November 1, 2004.
Landlord and Tenant acknowledge and agree that: (i) the determination of the
actual Commencement Date shall take into consideration the effect of any Tenant
Delays; and (ii) the Required Completion Date shall be postponed by the number
of days the actual Commencement Date is delayed due to events of Force Majeure.
Notwithstanding anything herein to the contrary, if Landlord determines in good
faith that it will be unable to cause the actual Commencement Date to occur by
the Required Completion Date, Landlord shall have the right to immediately cease
its performance of the Landlord Work and provide Tenant with written notice (the
"COMPLETION DATE EXTENSION NOTICE") of such inability, which Completion Date
Extension Notice shall set forth the date on which Landlord reasonably believes
that the actual Commencement Date will occur. Upon receipt of the Completion
Date Extension Notice, Tenant shall have the right to terminate this Lease by
providing written notice of termination to Landlord within 5 Business Days after
the date of Tenant's receipt of the Completion Date Extension Notice. If Tenant
does not terminate this Lease within such 5 Business Day period, the Required
Completion Date automatically shall be amended to be the date set forth in
Landlord's Completion Date Extension Notice.

      3.03 Subject to Landlord's obligation, if any, to perform Landlord Work
and except as otherwise expressly provided in this Section 3.03, the Premises
are accepted by Tenant in "as is" condition and configuration without any
representations or warranties by Landlord. By taking possession of the Premises,
Tenant agrees that the Premises are in good order and satisfactory condition.
Notwithstanding the foregoing, Landlord shall be responsible for latent defects
in the Landlord Work of which Tenant notifies Landlord to the extent that the
correction of such defects is covered under valid and enforceable warranties
given Landlord by contractors or subcontractors performing the Landlord Work.
Landlord, at its option, may pursue such claims directly or assign any such
warranties to Tenant for enforcement. Landlord shall not be liable for a failure
to deliver possession of the Premises or any other space due to the holdover or
unlawful possession of such space by another party, however Landlord shall use
reasonable efforts to obtain possession of the space. The commencement date for
the space, in such event, shall be postponed until the date Landlord delivers
possession of the Premises to Tenant free from occupancy by any party. If Tenant
takes possession of the Premises before the Commencement Date, such possession
shall be subject to the terms and conditions of this Lease and Tenant shall pay
Rent (defined in Section 4.01) to Landlord for each day of possession before the
Commencement Date. However, except for the cost of services requested by Tenant
(e.g. freight elevator usage), Tenant shall not be required to pay Rent for any
days of possession before the Commencement Date during which Tenant, with the
approval of Landlord, is in possession of the Premises for the sole purpose of
taking measurements, planning and/or performing improvements or installing
furniture, equipment or other personal property.

4. RENT.

      4.01 Tenant shall pay Landlord, without any setoff or deduction, unless
expressly set forth in this Lease, all Base Rent and Additional Rent due for the
Term (collectively referred to as "RENT"). "ADDITIONAL RENT" means all sums
(exclusive of Base Rent) that Tenant is required to pay Landlord under this
Lease. Tenant shall pay and be liable for all rental, sales and use taxes (but
excluding income taxes), if any, imposed upon or measured by Rent. Base Rent and
recurring monthly charges of Additional Rent shall be due and payable in advance
on the first day of each calendar month without notice or demand. All other
items of Rent shall be due and payable by Tenant on or before 30 days after
billing by Landlord. Rent shall be made payable to the entity, and sent to the
address, Landlord designates and shall be made by good and sufficient check or
by other means acceptable to Landlord. Tenant shall pay Landlord an
administration fee equal to 5% of all past due Rent, provided that Tenant shall
be entitled to a grace period of 5 days for the first 2 late payments of Rent in
a calendar year. In addition, past due Rent shall accrue interest at 12% per
annum. Landlord's acceptance of less than the correct amount of Rent shall be
considered a payment on account of the earliest Rent due. Rent for any partial
month during the Term shall be prorated. No endorsement or statement on a check
or letter accompanying payment shall be considered an accord and satisfaction.
Tenant's covenant to pay Rent is independent of every other covenant in this
Lease.

      4.02 Tenant shall pay Tenant's Pro Rata Share of Taxes and Expenses in
accordance with EXHIBIT B of this Lease.

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5. COMPLIANCE WITH LAWS; USE.

      The Premises shall be used for the Permitted Use and for no other use
whatsoever. Tenant shall comply with all statutes, codes, ordinances, orders,
rules and regulations of any municipal or governmental entity whether in effect
now or later, including the Americans with Disabilities Act ("LAW(S)"),
regarding the operation of Tenant's business and the use, condition,
configuration and occupancy of the Premises. In addition, Tenant shall, at its
sole cost and expense, promptly comply with any Laws that relate to the "Base
Building" (defined below), but only to the extent such obligations are triggered
by Tenant's use of the Premises, other than for general office use, or
Alterations or improvements in the Premises performed or requested by Tenant.
"BASE BUILDING" shall include the structural portions of the Building, the
public restrooms and the Building mechanical, electrical and plumbing systems
and equipment located in the internal core of the Building on the floor or
floors on which the Premises are located. Tenant shall promptly provide Landlord
with copies of any notices it receives regarding an alleged violation of Law.
Tenant shall comply with the rules and regulations of the Building attached as
EXHIBIT E and such other reasonable rules and regulations adopted by Landlord
from time to time, including rules and regulations for the performance of
Alterations (defined in Section 9).

6. SECURITY DEPOSIT.

      The Security Deposit shall be delivered to Landlord upon the execution of
this Lease by Tenant and held by Landlord without liability for interest (unless
required by Law) as security for the performance of Tenant's obligations. The
Security Deposit is not an advance payment of Rent or a measure of damages.
Landlord may use all or a portion of the Security Deposit to satisfy past due
Rent or to cure any Default (defined in Section 18) by Tenant. If Landlord uses
any portion of the Security Deposit, Tenant shall, within 5 days after demand,
restore the Security Deposit to its original amount. Landlord shall return any
unapplied portion of the Security Deposit to Tenant within 45 days after the
later to occur of: (a) determination of the final Rent due from Tenant; or (b)
the later to occur of the Termination Date or the date Tenant surrenders the
Premises to Landlord in compliance with Section 25. Landlord may assign the
Security Deposit to a successor or transferee and, following the assignment,
Landlord shall have no further liability for the return of the Security Deposit.
Landlord shall not be required to keep the Security Deposit separate from its
other accounts.

7. BUILDING SERVICES.

      7.01 Landlord shall furnish Tenant with the following services: (a) water
for use in the Base Building lavatories; (b) customary heat and air conditioning
in season during Building Service Hours, at such temperatures and in such
amounts as are standard for comparable buildings sufficient to maintain the
Premises at reasonably comfortable temperatures consistent with other class "A"
office buildings (provided, however, that Landlord shall not be liable for any
failure to maintain such temperatures to the extent such failure results from
(i) any density of occupancy within the Premises that exceeds the
occupancy-density level that is customary for general office use in class "A"
office buildings, (ii) any use of heat-generating equipment in concentrations or
quantities in excess of the average concentrations and quantities customarily
associated with general office use in class "A" office buildings, or (iii)
Tenant's failure to keep the window coverings in the Premises closed during
periods when the Premises are exposed to direct sunlight). Tenant shall have the
right to receive HVAC service during hours other than Building Service Hours by
paying Landlord's then standard charge for additional HVAC service and providing
such prior notice as is reasonably specified by Landlord. As of the date hereof,
Landlord's charge for after hours heating and air conditioning service is $30.00
per hour, subject to change from time to time; (c) standard janitorial service
on Business Days in accordance with the cleaning specifications attached hereto
as EXHIBIT G, or such other reasonably comparable specifications designated by
Landlord from time to time; (d) Elevator service; (e) Electricity in accordance
with the terms and conditions in Section 7.02; and (f) such other services as
Landlord reasonably determines are necessary or appropriate for the Property.

      7.02 Electricity used by Tenant in the Premises shall, at Landlord's
option, be paid for by Tenant either: (a) through inclusion in Expenses (except
as provided for excess usage); (b) by a separate charge payable by Tenant to
Landlord; or (c) by separate charge billed by the applicable utility company and
payable directly by Tenant. Without the consent of Landlord, Tenant's use of
electrical service shall not exceed, either in voltage, rated capacity, use
beyond Building Service Hours or overall load, that which Landlord reasonably
deems to be standard for the Building. Landlord shall have the right to measure
electrical usage by commonly accepted methods. If it is determined that Tenant
is using excess electricity, Tenant shall pay Landlord for the cost of such
excess electrical usage as Additional Rent.

      7.03 Landlord's failure to furnish, or any interruption, diminishment or
termination of services due to the application of Laws, the failure of any
equipment, the performance of repairs, improvements or alterations, utility
interruptions or the occurrence of an event of Force Majeure (defined in Section
26.03)

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(collectively a "SERVICE FAILURE") shall not render Landlord liable to Tenant,
constitute a constructive eviction of Tenant, give rise to an abatement of Rent,
nor relieve Tenant from the obligation to fulfill any covenant or agreement.
However, if the Premises, or a material portion of the Premises, are made
untenantable for a period in excess of 3 consecutive Business Days as a result
of a Service Failure that is reasonably within the control of Landlord to
correct, then Tenant, as its sole remedy, shall be entitled to receive an
abatement of Rent payable hereunder during the period beginning on the 4th
consecutive Business Day of the Service Failure and ending on the day the
service has been restored. If the entire Premises have not been rendered
untenantable by the Service Failure, the amount of abatement shall be equitably
prorated.

8. LEASEHOLD IMPROVEMENTS.

      All improvements in and to the Premises, including any Alterations
(collectively, "LEASEHOLD IMPROVEMENTS") shall remain upon the Premises at the
end of the Term without compensation to Tenant. Landlord, however, by written
notice to Tenant at least 30 days prior to the Termination Date, may require
Tenant, at its expense, to remove (a) any Cable (defined in Section 9.01)
installed by or for the benefit of Tenant, and (b) any Landlord Work or
Alterations that, in Landlord's reasonable judgment, are of a nature that would
require removal and repair costs that are materially in excess of the removal
and repair costs associated with standard office improvements (collectively
referred to as "REQUIRED REMOVABLES"). Required Removables shall include,
without limitation, internal stairways, raised floors, personal baths and
showers, vaults, rolling file systems and structural alterations and
modifications. The designated Required Removables shall be removed by Tenant
before the Termination Date. Tenant shall repair damage caused by the
installation or removal of Required Removables. If Tenant fails to perform its
obligations in a timely manner, Landlord may perform such work at Tenant's
expense. Tenant, at the time it requests approval for a proposed Alteration, may
request in writing that Landlord advise Tenant whether the Alteration or any
portion of the Alteration is a Required Removable. Within 10 days after receipt
of Tenant's request, Landlord shall advise Tenant in writing as to which
portions of the Alteration are Required Removables.

9. REPAIRS AND ALTERATIONS.

      9.01 Tenant shall periodically inspect the Premises to identify any
conditions that are dangerous or in need of maintenance or repair. Tenant shall
promptly provide Landlord with notice of any such conditions. Tenant shall, at
its sole cost and expense, perform all maintenance and repairs to the Premises
that are not Landlord's express responsibility under this Lease, and keep the
Premises in good condition and repair, reasonable wear and tear and damage by
Casualty (defined in Section 16.01 below) excepted. Tenant's repair and
maintenance obligations include, without limitation, repairs to: (a) floor
covering; (b) interior partitions; (c) doors; (d) the interior side of demising
walls; (e) electronic, phone and data cabling and related equipment that is
installed by or for the exclusive benefit of Tenant (collectively, "CABLE"); (f)
supplemental air conditioning units, kitchens, including hot water heaters,
plumbing, and similar facilities exclusively serving Tenant; and (g)
Alterations. To the extent Landlord is not reimbursed by insurance proceeds,
Tenant shall reimburse Landlord for the cost of repairing damage to the Building
caused by the acts of Tenant, Tenant Related Parties and their respective
contractors and vendors. If Tenant fails to make any repairs to the Premises for
more than 5 Business Days after notice from Landlord (although notice shall not
be required in an emergency) (which 5 Business Day period shall be extended for
such additional time (not to exceed 30 days) as shall be reasonably necessary
under the circumstances, provided that Tenant commences such repairs within such
5 Business Day period and diligently prosecute completion of the same), Landlord
may make the repairs, and Tenant shall pay the reasonable cost of the repairs,
together with an administrative charge in an amount equal to 10% of the cost of
the repairs.

      9.02 Landlord shall keep and maintain in good repair and working order and
perform maintenance upon the: (a) structural elements of the Building; (b)
mechanical (including HVAC), electrical, plumbing and fire/life safety systems
serving the Building in general; (c) Common Areas; (d) roof of the Building; (e)
exterior windows of the Building; and (f) elevators serving the Building.
Landlord shall promptly make repairs for which Landlord is responsible.

      9.03 Tenant shall not make alterations, repairs, additions or improvements
or install any Cable (collectively referred to as "ALTERATIONS") without first
obtaining the written consent of Landlord in each instance, which consent shall
not be unreasonably withheld or delayed. However, Landlord's consent shall not
be required for any Alteration that satisfies all of the following criteria (a
"COSMETIC ALTERATION"): (a) is of a cosmetic nature such as painting,
wallpapering, hanging pictures and installing carpeting; (b) is not visible from
the exterior of the Premises or Building; (c) will not affect the Base Building;
and (d) does not require work to be performed inside the walls or above the
ceiling of the Premises. Cosmetic Alterations shall be subject to all the other
provisions of this Section 9.03. Prior to starting work, Tenant shall furnish
Landlord with plans and specifications (except that no plans and specifications
shall be required for Cosmetic Alterations); names of contractors reasonably
acceptable to Landlord (provided that Landlord may designate specific
contractors with respect to Base Building); required permits and approvals;
evidence of contractor's and subcontractor's insurance in amounts

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reasonably required by Landlord and naming Landlord as an additional insured;
and any security for performance in amounts reasonably required by Landlord.
Changes to the plans and specifications must also be submitted to Landlord for
its approval. Alterations shall be constructed in a good and workmanlike manner
using materials of a quality reasonably approved by Landlord. Tenant shall
reimburse Landlord for any sums paid by Landlord for third party examination of
Tenant's plans for non-Cosmetic Alterations. In addition, Tenant shall pay
Landlord a fee for Landlord's oversight and coordination of any non-Cosmetic
Alterations equal to 10% of the cost of the Alterations. Upon completion, Tenant
shall furnish "as-built" plans for non-Cosmetic Alterations, completion
affidavits and full and final waivers of lien. Landlord's approval of an
Alteration shall not be deemed a representation by Landlord that the Alteration
complies with Law.

10. ENTRY BY LANDLORD.

      Landlord may enter the Premises to inspect, show or clean the Premises or
to perform or facilitate the performance of repairs, alterations or additions to
the Premises or any portion of the Building. Except in emergencies or to provide
Building services, Landlord shall provide Tenant with reasonable prior verbal
notice of entry and shall use reasonable efforts to minimize any interference
with Tenant's use of the Premises. If reasonably necessary, Landlord may
temporarily close all or a portion of the Premises to perform repairs,
alterations and additions. However, except in emergencies, Landlord will not
close the Premises if the work can reasonably be completed on weekends and after
Building Service Hours. Entry by Landlord shall not constitute a constructive
eviction or entitle Tenant to an abatement or reduction of Rent. Notwithstanding
the foregoing, if Landlord temporarily closes the Premises as provided above for
a period in excess of 3 consecutive Business Days, Tenant, as its sole remedy,
shall be entitled to receive a per diem abatement of Rent during the period
beginning on the 4th consecutive Business Day of closure and ending on the date
on which the Premises are returned to Tenant in a tenantable condition. Tenant,
however, shall not be entitled to an abatement if the repairs, alterations
and/or additions to be performed are required as a result of the acts or
omissions of Tenant, its agents, employees or contractors, including, without
limitation, a default by Tenant in its maintenance and repair obligations under
the Lease. If less than the entire Premises have been so closed, the amount of
abatement that Tenant is entitled to receive shall be prorated based upon the
percentage of the Premises unavailable for Tenant's use.

11. ASSIGNMENT AND SUBLETTING.

      11.01 Except in connection with a Permitted Transfer (defined in Section
11.04), Tenant shall not assign, sublease, transfer or encumber any interest in
this Lease or allow any third party to use any portion of the Premises
(collectively or individually, a "TRANSFER") without the prior written consent
of Landlord, which consent shall not be unreasonably withheld, conditioned or
delayed if Landlord does not exercise its recapture rights under Section 11.02.
If the entity which controls the voting shares/rights of Tenant changes at any
time, such change of ownership or control shall constitute a Transfer unless
Tenant is an entity whose outstanding stock is listed on a recognized securities
exchange or if at least 80% of its voting stock is owned by another entity, the
voting stock of which is so listed. Any attempted Transfer in violation of this
Section is voidable by Landlord. In no event shall any Transfer, including a
Permitted Transfer, release or relieve Tenant from any obligation under this
Lease.

      11.02 Tenant shall provide Landlord with financial statements for the
proposed transferee, a fully executed copy of the proposed assignment, sublease
or other Transfer documentation and such other information as Landlord may
reasonably request. Within 15 Business Days after receipt of the required
information and documentation, Landlord shall either: (a) consent to the
Transfer by execution of a consent agreement in a form reasonably designated by
Landlord; (b) reasonably refuse to consent to the Transfer in writing; or (c) in
the event of an assignment of this Lease or subletting of more than 20% of the
Rentable Square Footage of the Premises for more than 50% of the remaining Term
(excluding unexercised options), recapture the portion of the Premises that
Tenant is proposing to Transfer. If Landlord exercises its right to recapture,
this Lease shall automatically be amended (or terminated if the entire Premises
is being assigned or sublet) to delete the applicable portion of the Premises
effective on the proposed effective date of the Transfer. Tenant shall pay
Landlord a review fee of $1,500.00 for Landlord's review of any Permitted
Transfer or requested Transfer.

      11.03 Tenant shall pay Landlord 50% of all rent and other consideration
which Tenant receives as a result of a Transfer that is in excess of the Rent
payable to Landlord for the portion of the Premises and Term covered by the
Transfer. Tenant shall pay Landlord for Landlord's share of the excess within 30
days after Tenant's receipt of the excess. Tenant may first deduct from the
excess, on a straight-line basis, all reasonable and customary expenses directly
incurred by Tenant attributable to the Transfer, including, but not limited to,
brokerage fees, legal fees and construction costs. If Tenant is in Default,
Landlord may require that all sublease payments be made directly to Landlord, in
which case Tenant shall receive a credit against Rent in the amount of Tenant's
share of payments received by Landlord.

      11.04 Tenant may assign this Lease to a successor to Tenant by purchase,
merger, consolidation or reorganization (an "OWNERSHIP CHANGE") or assign this
Lease or sublet all or a portion of the Premises

                                       6
<PAGE>

to an Affiliate without the consent of Landlord, provided that all of the
following conditions are satisfied (a "PERMITTED TRANSFER"): (a) Tenant is not
in Default; (b) in the event of an Ownership Change, Tenant's successor shall
own substantially all of the assets of Tenant and have a net worth which is at
least equal to Tenant's net worth as of the day prior to the proposed Ownership
Change; (c) the Permitted Use does not allow the Premises to be used for retail
purposes; and (d) Tenant shall give Landlord written notice at least 15 Business
Days prior to the effective date of the Permitted Transfer unless Tenant is
prohibited from doing so by applicable Law (e.g. SEC regulations), in which
event Tenant shall give Landlord notice of such Permitted Transfer promptly
after Tenant is no longer so prohibited by such applicable Law. Tenant's notice
to Landlord shall include information and documentation evidencing the Permitted
Transfer and showing that each of the above conditions has been satisfied. If
requested by Landlord, Tenant's successor shall sign a commercially reasonable
form of assumption agreement in the case of any Transfer other than a sublease.
"AFFILIATE" shall mean an entity controlled by, controlling or under common
control with Tenant.

12. LIENS.

      Tenant shall not permit mechanics' or other liens to be placed upon the
Property, Premises or Tenant's leasehold interest in connection with any work or
service done or purportedly done by or for the benefit of Tenant or its
transferees. Tenant shall give Landlord notice at least 15 days prior to the
commencement of any work in the Premises to afford Landlord the opportunity,
where applicable, to post and record notices of non-responsibility. Tenant,
within 10 days of notice from Landlord, shall fully discharge any lien by
settlement, by bonding or by insuring over the lien in the manner prescribed by
the applicable lien Law. If Tenant fails to do so, Landlord may bond, insure
over or otherwise discharge the lien. Tenant shall reimburse Landlord for any
amount paid by Landlord, including, without limitation, reasonable attorneys'
fees.

13. INDEMNITY AND WAIVER OF CLAIMS.

      Tenant hereby waives all claims against and releases Landlord and its
trustees, members, principals, beneficiaries, partners, officers, directors,
employees, Mortgagees (defined in Section 23) and agents (the "LANDLORD RELATED
PARTIES") from all claims for any injury to or death of persons, damage to
property or business loss in any manner related to (a) Force Majeure, (b) acts
of third parties, (c) the bursting or leaking of any tank, water closet, drain
or other pipe, (d) the inadequacy or failure of any security services, personnel
or equipment, or (e) any matter not within the reasonable control of Landlord.
Except to the extent caused by the negligence or willful misconduct of Landlord
or any Landlord Related Parties, Tenant shall indemnify, defend and hold
Landlord and Landlord Related Parties harmless against and from all liabilities,
obligations, damages, penalties, claims, actions, costs, charges and expenses,
including, without limitation, reasonable attorneys' fees and other professional
fees (if and to the extent permitted by Law) (collectively referred to as
"LOSSES"), which may be imposed upon, incurred by or asserted against Landlord
or any of the Landlord Related Parties by any third party and arising out of or
in connection with any damage or injury occurring in the Premises or any acts or
omissions (including violations of Law) of Tenant, the Tenant Related Parties or
any of Tenant's transferees, contractors or licensees. Except to the extent
caused by the negligence or willful misconduct of Tenant or any Tenant Related
Parties, Landlord shall indemnify, defend and hold Tenant, its trustees,
members, principals, beneficiaries, partners, officers, directors, employees and
agents ("TENANT RELATED PARTIES") harmless against and from all Losses which may
be imposed upon, incurred by or asserted against Tenant or any of the Tenant
Related Parties by any third party and arising out of or in connection with the
acts or omissions (including violations of Law) of Landlord or the Landlord
Related Parties.

14. INSURANCE.

      Tenant shall maintain the following insurance ("TENANT'S INSURANCE"): (a)
Commercial General Liability Insurance applicable to the Premises and its
appurtenances providing, on an occurrence basis, a minimum combined single limit
of $2,000,000.00; (b) Property/Business Interruption Insurance written on an All
Risk or Special Perils form, with coverage for broad form water damage including
earthquake sprinkler leakage, at replacement cost value and with a replacement
cost endorsement covering all of Tenant's business and trade fixtures,
equipment, movable partitions, furniture, merchandise and other personal
property within the Premises ("TENANT'S PROPERTY") and any Leasehold
Improvements performed by or for the benefit of Tenant; (c) Workers'
Compensation Insurance in amounts required by Law; and (d) Employers Liability
Coverage of at least $1,000,000.00 per occurrence (provided that if this
coverage is unavailable from the Worker's Compensation carrier or applicable
State Fund, a "Stop Gap Liability" endorsement to the Commercial General
Liability Policy is acceptable). Any company writing Tenant's Insurance shall
have an A.M. Best rating of not less than A-VIII. All Commercial General
Liability Insurance policies shall name as additional insureds Landlord (or its
successors and assignees), the managing agent for the Building (or any
successor), EOP Operating Limited Partnership, Equity Office Properties Trust
and their respective members, principals, beneficiaries, partners, officers,
directors, employees, and agents, and other designees of Landlord and its
successors as the interest of such designees shall appear. All policies of
Tenant's Insurance shall contain endorsements that the

                                       7
<PAGE>

insurer(s) shall give Landlord and its designees at least 30 days' advance
written notice of any cancellation, termination, material change or lapse of
insurance. Tenant shall provide Landlord with a certificate of insurance
evidencing Tenant's Insurance prior to the earlier to occur of the Commencement
Date or the date Tenant is provided with possession of the Premises, and
thereafter as necessary to assure that Landlord always has current certificates
evidencing Tenant's Insurance. Landlord shall maintain so called All Risk
property insurance on the Building at replacement cost value as reasonably
estimated by Landlord.

15. SUBROGATION.

      Landlord and Tenant hereby waive and shall cause their respective
insurance carriers to waive any and all rights of recovery, claims, actions or
causes of action against the other for any loss or damage with respect to
Tenant's Property, Leasehold Improvements, the Building, the Premises, or any
contents thereof, including rights, claims, actions and causes of action based
on negligence, which loss or damage is (or would have been, had the insurance
required by this Lease been carried) covered by insurance.

16. CASUALTY DAMAGE.

      16.01 If all or any portion of the Premises becomes untenantable by fire
or other casualty to the Premises (collectively a "CASUALTY"), Landlord, with
reasonable promptness, shall cause a general contractor selected by Landlord to
provide Landlord and Tenant with a written estimate of the amount of time
required using standard working methods to Substantially Complete the repair and
restoration of the Premises and any Common Areas necessary to provide access to
the Premises ("COMPLETION ESTIMATE"). If the Completion Estimate indicates that
the Premises or any Common Areas necessary to provide access to the Premises
cannot be made tenantable within 210 days from the date the repair is started,
then either party shall have the right to terminate this Lease upon written
notice to the other within 10 days after receipt of the Completion Estimate. In
addition, Tenant shall have the right to terminate this Lease if: (a) a
substantial portion of the Premises has been damaged by Casualty and such damage
cannot reasonably be repaired within 60 days after Tenant receives the
Completion Estimate; (b) there is less than 1 year of the Term remaining on the
date of such casualty, and (c) Tenant provides Landlord with written notice of
its intent to terminate within 30 days after receipt of the Completion Estimate.
Tenant, however, shall not have the right to terminate this Lease if the
Casualty was caused by the negligence or intentional misconduct of Tenant or any
Tenant Related Parties. In addition, Landlord, by notice to Tenant within 90
days after the date of the Casualty, shall have the right to terminate this
Lease if: (1) the Premises have been materially damaged and there is less than 1
year of the Term remaining on the date of the Casualty; (2) any Mortgagee
requires that the insurance proceeds be applied to the payment of the mortgage
debt; or (3) a material uninsured loss to the Building occurs (provided that
Landlord has maintained the insurance required hereunder).

      16.02 If this Lease is not terminated, Landlord shall promptly and
diligently, subject to reasonable delays for insurance adjustment or other
matters beyond Landlord's reasonable control, restore the Premises (including
the Leasehold Improvements) and Common Areas. Such restoration shall be to
substantially the same condition that existed prior to the Casualty, except for
modifications required by Law or any other modifications to the Common Areas
deemed desirable by Landlord. Upon notice from Landlord, Tenant shall assign to
Landlord (or to any party designated by Landlord) all property insurance
proceeds payable to Tenant under Tenant's Insurance with respect to any
Leasehold Improvements performed by or for the benefit of Tenant; provided if
the estimated cost to repair such Leasehold Improvements exceeds the amount of
insurance proceeds received by Landlord from Tenant's insurance carrier, the
excess cost of such repairs shall be paid by Tenant to Landlord prior to
Landlord's commencement of repairs. Within 15 days of demand, Tenant shall also
pay Landlord for any additional excess costs that are reasonably determined
during the performance of the repairs. Landlord shall not be liable for any
inconvenience to Tenant, or injury to Tenant's business resulting in any way
from the Casualty or the repair thereof. Provided that Tenant is not in Default,
during any period of time that all or a material portion of the Premises is
rendered untenantable as a result of a Casualty, the Rent shall abate for the
portion of the Premises that is untenantable and not used by Tenant.
Notwithstanding the foregoing, if Tenant was entitled to but elected not to
exercise its right to terminate the Lease and Landlord does not substantially
complete the repair and restoration of the Premises within 2 months after the
expiration of the estimated period of time set forth in the Completion Estimate,
which period shall be extended to the extent of any Reconstruction Delays, then
Tenant may terminate this Lease by written notice to Landlord within 15 days
after the expiration of such period, as the same may be extended. For purposes
of this Lease, the term "RECONSTRUCTION DELAYS" shall mean: (i) any delays
caused by the insurance adjustment process; (ii) any delays caused by Tenant;
and (iii) any delays caused by events of Force Majeure.

17. CONDEMNATION.

      Either party may terminate this Lease if any material part of the Premises
is taken or condemned for any public or quasi-public use under Law, by eminent
domain or private purchase in lieu thereof (a

                                       8
<PAGE>

"TAKING"). Landlord shall also have the right to terminate this Lease if there
is a Taking of any portion of the Building or Property which would have a
material adverse effect on Landlord's ability to profitably operate the
remainder of the Building. The terminating party shall provide written notice of
termination to the other party within 45 days after it first receives notice of
the Taking. The termination shall be effective on the date the physical taking
occurs. If this Lease is not terminated, Base Rent and Tenant's Pro Rata Share
shall be appropriately adjusted to account for any reduction in the square
footage of the Building or Premises. All compensation awarded for a Taking shall
be the property of Landlord. The right to receive compensation or proceeds are
expressly waived by Tenant, however, Tenant may file a separate claim for
Tenant's Property and Tenant's reasonable relocation expenses, provided the
filing of the claim does not diminish the amount of Landlord's award. If only a
part of the Premises is subject to a Taking and this Lease is not terminated,
Landlord, with reasonable diligence, will restore the remaining portion of the
Premises as nearly as practicable to the condition immediately prior to the
Taking.

18. EVENTS OF DEFAULT.

      Each of the following occurrences shall be a "DEFAULT": (a) Tenant's
failure to pay any portion of Rent when due, if the failure continues for 3 days
after written notice to Tenant ("MONETARY DEFAULT"); (b) Tenant's failure (other
than a Monetary Default) to comply with any term, provision, condition or
covenant of this Lease, if the failure is not cured within 20 days after written
notice to Tenant provided, however, if Tenant's failure to comply cannot
reasonably be cured within 20 days, Tenant shall be allowed additional time (not
to exceed 90 days) as is reasonably necessary to cure the failure so long as
Tenant begins the cure within 20 days and diligently pursues the cure to
completion; (c) Tenant or any Guarantor becomes insolvent, makes a transfer in
fraud of creditors, makes an assignment for the benefit of creditors, admits in
writing its inability to pay its debts when due or forfeits or loses its right
to conduct business; (d) the leasehold estate is taken by process or operation
of Law; (e) in the case of any ground floor or retail Tenant, Tenant does not
take possession of or abandons or vacates all or any portion of the Premises; or
(f) Tenant is in default beyond any notice and cure period under any other lease
or agreement with Landlord at the Building or Property. If Landlord provides
Tenant with notice of Tenant's failure to comply with any specific provision of
this Lease on 3 separate occasions during any 12 month period, Tenant's
subsequent violation of such provision shall, at Landlord's option, be an
incurable Default by Tenant. All notices sent under this Section shall be in
satisfaction of, and not in addition to, notice required by Law.

19. REMEDIES.

      19.01 Upon Default, Landlord shall have the right to pursue any one or
more of the following remedies:

            (a) Terminate this Lease, in which case Tenant shall immediately
      surrender the Premises to Landlord. If Tenant fails to surrender the
      Premises, Landlord, in compliance with Law, may enter upon and take
      possession of the Premises and remove Tenant, Tenant's Property and any
      party occupying the Premises. Tenant shall pay Landlord, on demand, all
      past due Rent and other losses and damages Landlord suffers as a result of
      Tenant's Default, including, without limitation, all Costs of Reletting
      (defined below) and any deficiency that may arise from reletting or the
      failure to relet the Premises. "COSTS OF RELETTING" shall include all
      reasonable costs and expenses incurred by Landlord in reletting or
      attempting to relet the Premises, including, without limitation, legal
      fees, brokerage commissions, the cost of alterations and the value of
      other concessions or allowances granted to a new tenant.

            (b) Terminate Tenant's right to possession of the Premises and, in
      compliance with Law, remove Tenant, Tenant's Property and any parties
      occupying the Premises. Landlord may (but shall not be obligated to) relet
      all or any part of the Premises, without notice to Tenant, for such period
      of time and on such terms and conditions (which may include concessions,
      free rent and work allowances) as Landlord in its absolute discretion
      shall determine. Landlord may collect and receive all rents and other
      income from the reletting. Tenant shall pay Landlord on demand all past
      due Rent, all Costs of Reletting and any deficiency arising from the
      reletting or failure to relet the Premises. The re-entry or taking of
      possession of the Premises shall not be construed as an election by
      Landlord to terminate this Lease.

      19.02 In lieu of calculating damages under Section 19.01, Landlord may
elect to receive as damages the sum of (a) all Rent accrued through the date of
termination of this Lease or Tenant's right to possession, and (b) an amount
equal to the total Rent that Tenant would have been required to pay for the
remainder of the Term discounted to present value, minus the then present fair
rental value of the Premises for the remainder of the Term, similarly
discounted, after deducting all anticipated Costs of Reletting. If Tenant is in
Default of any of its non-monetary obligations under the Lease, Landlord shall
have the right to perform such obligations. Tenant shall reimburse Landlord for
the cost of such performance upon demand together with an administrative charge
equal to 10% of the cost of the work performed by Landlord. The repossession or
re-entering of all or any part of the Premises shall not relieve Tenant of its
liabilities and obligations under this Lease. No right or remedy of Landlord
shall be

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<PAGE>

exclusive of any other right or remedy. Each right and remedy shall be
cumulative and in addition to any other right and remedy now or subsequently
available to Landlord at Law or in equity.

20. LIMITATION OF LIABILITY.

      NOTWITHSTANDING ANYTHING TO THE CONTRARY CONTAINED IN THIS LEASE, THE
LIABILITY OF LANDLORD (AND OF ANY SUCCESSOR LANDLORD) SHALL BE LIMITED TO THE
LESSER OF (A) THE INTEREST OF LANDLORD IN THE PROPERTY, OR (B) THE EQUITY
INTEREST LANDLORD WOULD HAVE IN THE PROPERTY IF THE PROPERTY WERE ENCUMBERED BY
THIRD PARTY DEBT IN AN AMOUNT EQUAL TO 70% OF THE VALUE OF THE PROPERTY. TENANT
SHALL LOOK SOLELY TO LANDLORD'S INTEREST IN THE PROPERTY FOR THE RECOVERY OF ANY
JUDGMENT OR AWARD AGAINST LANDLORD OR ANY LANDLORD RELATED PARTY. NEITHER
LANDLORD NOR ANY LANDLORD RELATED PARTY SHALL BE PERSONALLY LIABLE FOR ANY
JUDGMENT OR DEFICIENCY, AND IN NO EVENT SHALL LANDLORD OR ANY LANDLORD RELATED
PARTY BE LIABLE TO TENANT FOR ANY LOST PROFIT, DAMAGE TO OR LOSS OF BUSINESS OR
ANY FORM OF SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGE. BEFORE FILING SUIT FOR AN
ALLEGED DEFAULT BY LANDLORD, TENANT SHALL GIVE LANDLORD AND THE MORTGAGEE(S)
WHOM TENANT HAS BEEN NOTIFIED HOLD MORTGAGES (DEFINED IN SECTION 23 BELOW),
NOTICE AND REASONABLE TIME TO CURE THE ALLEGED DEFAULT.

21. RELOCATION.

      Landlord, at its expense, at any time before or during the Term, may
relocate Tenant from all or any portion of the Premises (provided, however, that
Landlord may not relocate Tenant from any portion of any floor of the Building
unless Landlord relocates Tenant from the entirety of the portion of the
Premises that is located on such floor) to space of reasonably comparable size
and utility ("RELOCATION SPACE") within the Building upon 60 days' prior written
notice to Tenant, provided that if Landlord shall relocate Tenant from the
portion of the Premises located on the 6th floor of the Building, the Relocation
Space for such portion of the Premises shall be located on or above the 7th
floor of the Building. Notwithstanding the foregoing, Landlord shall not be
entitled to relocate Tenant during the period beginning October 15th of any
calendar year and ending January 15th of the immediately following calendar
year. The Relocation Space for the Premises (or any portion thereof) must
contain similar finishes as the Premises (or such portion thereof), and
approximately the same Rentable Square Footage as the Premises (or such portion
thereof) and the same number of work stations, offices, breakrooms and reception
areas as are contained in the Premises (or such portion thereof) as of the date
Tenant receives Landlord's notice of relocation. In addition, any Relocation
Space for any portion of the Premises located on any single floor of the
Building shall be not be deemed to be of reasonably comparable size and utility
unless such Relocation Space is located on a single floor of the Building. From
and after the date of the relocation, the Base Rent and Tenant's Pro Rata Share
shall be adjusted based on the rentable square footage of the Relocation Space.
Landlord shall pay Tenant's reasonable costs of relocation, including all costs
for moving Tenant's furniture, equipment, supplies and other personal property,
as well as the cost of printing and distributing change of address notices to
Tenant's customers and one month's supply of stationery showing the new address.
Landlord shall also reimburse Tenant for the reasonable cost to install and
connect telecommunication and data cabling in the Relocation Space in the manner
and to the extent such cabling existed in the Premises (or the applicable
portion thereof) prior to the relocation. Notwithstanding anything to the
contrary contained in this Section 21, Landlord shall have no right, pursuant to
this Section 21, to relocate Tenant from any portion of the Premises, other than
from the portion of the Premises located on the 3rd floor, unless: (i) such
relocation is necessary to enable a Qualified Tenant (defined below) to lease
such portion of the Premises, and (ii) such portion of the Premises is located
either (a) adjacent to all or any portion of the Qualified Space (defined below)
on the same floor of the Building, or (b) on a floor of the Building located
immediately above or below a floor containing all or any portion of the
Qualified Space. As used herein, "QUALIFIED TENANT" shall mean, at any time, a
tenant of the Building then occupying space in the Building ("QUALIFIED SPACE")
having a size exceeding the total rentable square footage of the Premises.

22. HOLDING OVER.

      If Tenant fails to surrender all or any part of the Premises at the
termination of this Lease, occupancy of the Premises after termination shall be
that of a tenancy at sufferance. Tenant's occupancy shall be subject to all the
terms and provisions of this Lease, and Tenant shall pay an amount (on a per
month basis without reduction for partial months during the holdover) equal to
150% of the sum of the Base Rent and Additional Rent due for the period
immediately preceding the holdover. No holdover by Tenant or payment by Tenant
after the termination of this Lease shall be construed to extend the Term or
prevent Landlord from immediate recovery of possession of the Premises by
summary proceedings or otherwise. If Landlord is unable to deliver possession of
the Premises to a new tenant or to perform improvements for a new tenant as a
result of Tenant's holdover and Tenant fails to vacate the Premises within 15
days after notice from Landlord, Tenant shall be liable for all damages that
Landlord suffers from the holdover.

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<PAGE>

23. SUBORDINATION TO MORTGAGES; ESTOPPEL CERTIFICATE.

      Tenant accepts this Lease subject and subordinate to any mortgage(s),
deed(s) of trust, ground lease(s) or other lien(s) subsequently arising upon the
Premises, the Building or the Property, and to renewals, modifications,
refinancings and extensions thereof (collectively referred to as a "MORTGAGE").
The party having the benefit of a Mortgage shall be referred to as a
"MORTGAGEE". This clause shall be self-operative, but upon request from a
Mortgagee, Tenant shall execute a commercially reasonable subordination
agreement in favor of the Mortgagee. As an alternative, a Mortgagee shall have
the right at any time to subordinate its Mortgage to this Lease. Upon request,
Tenant, without charge, shall attorn to any successor to Landlord's interest in
this Lease, provided any successor-in-interest pursuant to a voluntary, third
party transfer (but not as part of an involuntary transfer resulting from a
foreclosure or deed in lieu thereof) shall have assumed Landlord's obligations
under this Lease. Landlord and Tenant shall each, within 10 days after receipt
of a written request from the other, execute and deliver a commercially
reasonable estoppel certificate to those parties as are reasonably requested by
the other (including a Mortgagee or prospective purchaser). Without limitation,
such estoppel certificate may include a certification as to the status of this
Lease, the existence of any defaults and the amount of Rent that is due and
payable. Notwithstanding the foregoing in this Section 23 to the contrary, as a
condition precedent to the future subordination of this Lease to a future
Mortgage, Landlord shall be required to provide Tenant with a non-disturbance,
subordination, and attornment agreement in favor of Tenant from any Mortgagee
who comes into existence after the Commencement Date. Such non-disturbance,
subordination, and attornment agreement in favor of Tenant shall provide that,
so long as Tenant is paying the Rent due under the Lease and is not otherwise in
Default under the Lease, its right to possession and the other terms of the
Lease shall remain in full force and effect. Such non-disturbance,
subordination, and attornment agreement may include other commercially
reasonable provisions in favor of the Mortgagee, including, without limitation,
additional time on behalf of the Mortgagee to cure defaults of the Landlord and
provide that (a) neither Mortgagee nor any successor-in-interest shall be bound
by (i) any payment of the Base Rent, Additional Rent, or other sum due under
this Lease for more than 1 month in advance or (ii) any amendment or
modification of the Lease made without the express written consent of Mortgagee
or any successor-in-interest; (b) neither Mortgagee nor any
successor-in-interest will be liable for (i) any act or omission or warranties
of any prior landlord (including Landlord), (ii) the breach of any warranties or
obligations relating to construction of improvements on the Property or any
tenant finish work performed or to have been performed by any prior landlord
(including Landlord), or (iii) the return of any security deposit, except to the
extent such deposits have been received by Mortgagee; and (c) neither Mortgagee
nor any successor-in-interest shall be subject to any offsets or defenses which
Tenant might have against any prior landlord (including Landlord). Landlord
represents to Tenant that no Mortgage entered into by Landlord exists as of the
date of this Lease.

24. NOTICE.

      All demands, approvals, consents or notices (collectively referred to as a
"NOTICE") shall be in writing and delivered by hand or sent by registered or
certified mail with return receipt requested or sent by overnight or same day
courier service at the party's respective Notice Address(es) set forth in
Section 1. Each notice shall be deemed to have been received on the earlier to
occur of actual delivery or the date on which delivery is refused, or, if Tenant
has vacated the Premises or any other Notice Address of Tenant without providing
a new Notice Address, 3 days after notice is deposited in the U.S. mail or with
a courier service in the manner described above. Either party may, at any time,
change its Notice Address (other than to a post office box address) by giving
the other party written notice of the new address.

25. SURRENDER OF PREMISES.

      At the termination of this Lease or Tenant's right of possession, Tenant
shall remove Tenant's Property from the Premises, and quit and surrender the
Premises to Landlord, broom clean, and in good order, condition and repair,
ordinary wear and tear and damage by Casualty or which Landlord is otherwise
obligated to repair hereunder excepted. If Tenant fails to remove any of
Tenant's Property within 2 days after termination of this Lease or Tenant's
right to possession, Landlord, at Tenant's sole cost and expense, shall be
entitled (but not obligated) to remove and store Tenant's Property. Landlord
shall not be responsible for the value, preservation or safekeeping of Tenant's
Property. Tenant shall pay Landlord, upon demand, the expenses and storage
charges incurred. If Tenant fails to remove Tenant's Property from the Premises
or storage, within 30 days after notice, Landlord may deem all or any part of
Tenant's Property to be abandoned and title to Tenant's Property shall vest in
Landlord.

26. MISCELLANEOUS.

      26.01 This Lease shall be interpreted and enforced in accordance with the
Laws of the state or commonwealth in which the Building is located and Landlord
and Tenant hereby irrevocably consent to the jurisdiction and proper venue of
such state or commonwealth. If any term or provision of this Lease

                                       11
<PAGE>

shall to any extent be void or unenforceable, the remainder of this Lease shall
not be affected. If there is more than one Tenant or if Tenant is comprised of
more than one party or entity, the obligations imposed upon Tenant shall be
joint and several obligations of all the parties and entities, and requests or
demands from any one person or entity comprising Tenant shall be deemed to have
been made by all such persons or entities. Notices to any one person or entity
shall be deemed to have been given to all persons and entities. Tenant
represents and warrants to Landlord that each individual executing this Lease on
behalf of Tenant is authorized to do so on behalf of Tenant and that Tenant is
not, and the entities or individuals constituting Tenant or which may own or
control Tenant or which may be owned or controlled by Tenant are not, among the
individuals or entities identified on any list compiled pursuant to Executive
Order 13224 for the purpose of identifying suspected terrorists.

      26.02 If either party institutes a suit against the other for violation of
or to enforce any covenant, term or condition of this Lease, the prevailing
party shall be entitled to all of its costs and expenses, including, without
limitation, reasonable attorneys' fees. Landlord and Tenant hereby waive any
right to trial by jury in any proceeding based upon a breach of this Lease.
Either party's failure to declare a default immediately upon its occurrence, or
delay in taking action for a default, shall not constitute a waiver of the
default, nor shall it constitute an estoppel.

      26.03 Whenever a period of time is prescribed for the taking of an action
by Landlord or Tenant (other than the payment of the Security Deposit or Rent),
the period of time for the performance of such action shall be extended by the
number of days that the performance is actually delayed due to strikes, acts of
God, shortages of labor or materials, war, terrorist acts, civil disturbances
and other causes beyond the reasonable control of the performing party
(excluding economic or financing difficulties) ("FORCE MAJEURE").

      26.04 Landlord shall have the right to transfer and assign, in whole or in
part, all of its rights and obligations under this Lease and in the Building and
Property. Upon transfer Landlord shall be released from any further obligations
hereunder and Tenant agrees to look solely to the successor in interest of
Landlord for the performance of such obligations, provided that, any successor
pursuant to a voluntary, third party transfer (but not as part of an involuntary
transfer resulting from a foreclosure or deed in lieu thereof) shall have
assumed Landlord's obligations under this Lease.

      26.05 Landlord has delivered a copy of this Lease to Tenant for Tenant's
review only and the delivery of it does not constitute an offer to Tenant or an
option.

            (a) Tenant represents that it has dealt directly with and only with
      Tenant's Broker as a broker in connection with this Lease. Tenant shall
      indemnify and hold Landlord and the Landlord Related Parties harmless from
      all claims of any other brokers claiming to have represented Tenant in
      connection with this Lease. Landlord agrees to indemnify and hold Tenant
      and the Tenant Related Parties harmless from all claims of any brokers
      claiming to have represented Landlord in connection with this Lease.

            (b) Agency Disclosure. At the signing of this Lease, Landlord's
      leasing agent, Sharon Johnson, of Equity Office Properties Management
      Corp. represented (X) Landlord, (__) Tenant, or (__) both Landlord and
      Tenant. At the signing of this Lease, Tenant's agent, Mike Schreck, of
      Colliers International, represented (__) Landlord, (X) Tenant, or (__)
      both Landlord and Tenant. Each party signing this document confirms that
      the prior oral and/or written disclosure of agency was provided to such
      party in this transaction, as required by RCW 18.86.030(1)(g).

            (c) Landlord and Tenant, by their execution of this Lease, each
      acknowledge and agree that they have timely received a pamphlet on the law
      of real estate agency as required under RCW 18.86.030(1)(f).

      26.06 Time is of the essence with respect to Tenant's exercise of any
expansion, renewal or extension rights granted to Tenant. The expiration of the
Term, whether by lapse of time, termination or otherwise, shall not relieve
either party of any obligations which accrued prior to or which may continue to
accrue after the expiration or termination of this Lease.

      26.07 Tenant may peacefully have, hold and enjoy the Premises, subject to
the terms of this Lease, provided Tenant pays the Rent and fully performs all of
its covenants and agreements. This covenant shall be binding upon Landlord and
its successors only during its or their respective periods of ownership of the
Building.

      26.08 This Lease does not grant any rights to light or air over or about
the Building. Landlord excepts and reserves exclusively to itself any and all
rights not specifically granted to Tenant under this Lease. This Lease
constitutes the entire agreement between the parties and supersedes all prior
agreements and understandings related to the Premises, including all lease
proposals, letters of intent and other documents. Neither party is relying upon
any warranty, statement or representation not

                                       12
<PAGE>

contained in this Lease. This Lease may be modified only by a written agreement
signed by an authorized representative of Landlord and Tenant.

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

                               LANDLORD:

                               EOP OPERATING LIMITED PARTNERSHIP,
                               A DELAWARE LIMITED PARTNERSHIP

                               By: Equity Office Properties Trust, a Maryland
                                   real estate investment trust, its general
                                   partner

                                   By: /S/ M. PATRICK CALIAHAN
                                       --------------------------------------
                                       M. PATRICK CALIAHAN
                                       SENIOR VICE PRESIDENT - SEATTLE REGION

                               TENANT:

                               LIGHTBRIDGE, INC., A DELAWARE CORPORATION

                               By: /S/ PAMELA D. A. REEVE
                                   ------------------------------------------
                                   PAMELA D.A. REEVE
                                   PRESIDENT

                               Tenant's Tax ID Number (SSN or FEIN): 04-306540

                                       13
<PAGE>

                            LANDLORD ACKNOWLEDGMENTS

STATE OF Washington   )
COUNTY OF King        )ss:

      I, the undersigned, a Notary Public, in and for the County and State
aforesaid, do hereby certify that Susan J. Murphy, personally known to me to be
the Vice President - Leasing of Equity Office Properties Trust, a Maryland real
estate investment trust, and personally known to me to be the same person whose
name is subscribed to the foregoing instrument, appeared before me this day in
person and acknowledged that as such officer of said entity being authorized so
to do, (s)he executed the foregoing instrument on behalf of said entity, by
subscribing the name of such entity by himself/herself as such officer, as a
free and voluntary act, and as the free and voluntary act and deed of said
entity under the foregoing instrument for the uses and purposes therein set
forth.

      GIVEN under my hand and official seal this 10th day of August, 2004.

                                                  /s/ Tanya M. Hopkins
                                            ----------------------------------
                                                    Notary Public

My Commission Expires:  9-19-04

                             TENANT ACKNOWLEDGMENTS

STATE OF  Massachusetts    )
COUNTY OF Middlesex        )ss:

      On this the 23rd day of July, 2004, before me a Notary Public duly
authorized in and for the said County in the State aforesaid to take
acknowledgments personally appeared Pamela D.A. Reeve, known to me to be the
President of LIGHTBRIDGE, INC., a Delaware corporation, one of the parties
described in the foregoing instrument, and acknowledged that as such officer,
being authorized so to do, (s)he executed the foregoing instrument on behalf of
said corporation by subscribing the name of such corporation by himself/herself
as such officer and caused the corporate seal of said corporation to be affixed
thereto, as a free and voluntary act, and as the free and voluntary act of said
corporation, for the uses and purposes therein set forth.

      IN WITNESS WHEREOF, I hereunto set my hand and official seal.

                                                 /s/ Debra A. Michelson
                                            -----------------------------------
                                                     Notary Public

My Commission Expires: 9-1-06

                                        1
<PAGE>

                                    EXHIBIT A

                        OUTLINE AND LOCATION OF PREMISES

                                       1
<PAGE>

                                   EXHIBIT A-1

                     OUTLINE AND LOCATION OF MUST TAKE SPACE

                                       1
<PAGE>

                                   EXHIBIT A-2

                                LEGAL DESCRIPTION

THE LAND REFERRED TO HEREIN IS SITUATED IN THE STATE OF WASHINGTON, COUNTY OF
KING, AND IS DESCRIBED AS FOLLOWS:

PARCEL A:

LOTS 5, 6, 7 AND 8, BLOCK 1, CARROLL-HEDLUND'S 1ST ADDITION TO BELLEVUE
ACCORDING TO THE PLAT THEREOF, RECORDED IN VOLUME 49 OF PLATS, PAGE(S) 58 AND
59, IN KING COUNTY, WASHINGTON;

EXCEPT THAT PORTION OF SAID LOT 8 LYING EASTERLY OF A LINE THAT IS 30 FEET WEST
OF THE EAST LINE OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF THE
SOUTHEAST QUARTER OF SECTION 29.

PARCEL B:

THAT PORTION OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF THE SOUTHEAST
QUARTER OF SECTION 29, TOWNSHIP 25 NORTH, RANGE 5 EAST, WILLAMETTE MERIDIAN, IN
KING COUNTY, WASHINGTON, DESCRIBED AS FOLLOWS:

BEGINNING AT THE POINT OF INTERSECTION OF THE WEST LINE OF THE EAST 92 FEET OF
SAID SUBDIVISION WITH THE FORMER NORTH LINE OF NORTHEAST 8TH STREET, SAID POINT
BEING NORTH 01 DEGREE 13'30" EAST, A DISTANCE OF 33.00 FEET FROM THE SOUTH LINE
OF SAID SUBDIVISION;

THENCE NORTH 01 DEGREE 13'30" EAST, A DISTANCE OF 147.01 FEET TO THE SOUTH LINE
OF CARROLL-HEDLUND'S 1ST ADDITION TO BELLEVUE, ACCORDING TO THE PLAT THEREOF,
RECORDED IN VOLUME 49 OF PLATS, PAGES 58 AND 59, IN KING COUNTY, WASHINGTON;

THENCE NORTH 88 DEGREES 04'22" WEST ALONG SAID SOUTH LINE, A DISTANCE OF 172.02
FEET TO THE WEST LINE OF SAID PLAT OF CARROLL-HEDLUND'S 1ST ADDITION TO BELLEVUE
PRODUCED SOUTH;

THENCE NORTH 01 DEGREE 13'30" EAST ALONG SAID WEST LINE TO THE NORTHEAST CORNER
OF THE PROPERTY CONVEYED TO JEFFREY BUILDING COMPANY BY DEED RECORDED UNDER
RECORDING NUMBER 7608310501;

THENCE WEST ALONG THE NORTH LINE OF SAID PROPERTY CONVEYED BY RECORDING NUMBER
7608310501, A DISTANCE OF 241 FEET TO THE NORTHWEST CORNER THEREOF, SAID POINT
BEING ON THE EAST LINE OF THE PROPERTY SOLD TO JEFFREY BUILDING COMPANY UNDER
INSTRUMENT RECORDED UNDER RECORDING NUMBER 6199084;

THENCE NORTH ALONG SAID EAST LINE TO THE NORTHEAST CORNER THEREOF, BEING A POINT
ON THE SOUTH LINE OF THE NORTH 315 FEET OF SAID SUBDIVISION; THENCE WEST ALONG
THE SOUTH LINE OF SAID NORTH 315 FEET TO THE EAST LINE OF 108TH AVENUE
NORTHEAST;

THENCE SOUTH 01 DEGREE 20'51" EAST ALONG SAID EAST LINE 305.02 FEET TO A POINT
ON THE NORTH LINE OF THE NORTHEAST 8TH STREET, BEING 40 FEET NORTHERLY OF THE
SOUTH LINE OF SAID SUBDIVISION;

THENCE ALONG THE NORTHERLY LINE OF SAID STREET THE FOLLOWING COURSES AND
DISTANCES;

THENCE SOUTH 88 DEGREES 04'22" EAST, A DISTANCE OF 185.71 FEET;

THENCE SOUTH 01 DEGREE 20'30" WEST 7.00 FEET;

THENCE SOUTH 88 DEGREES 04'22" EAST 180.53 FEET;

THENCE SOUTH 01 DEGREE 13'30" WEST 3.00 FEET;

THENCE SOUTH 88 DEGREES 04'22" EAST 80.02 FEET;

THENCE NORTH 01 DEGREE 13'30" EAST 3.00 FEET;

THENCE SOUTH 88 DEGREES 04'22" EAST 92.00 FEET, TO THE POINT OF BEGINNING;

EXCEPT THAT PORTION LYING EAST OF THE SOUTHERLY PRODUCTION OF THE WEST LINE OF
CARROLL-HEDLUND'S 1ST ADDITION TO BELLEVUE, ACCORDING TO THE PLAT THEREOF;
RECORDED IN VOLUME 49 OF PLATS, PAGES 58 AND 59, IN KING COUNTY, WASHINGTON;

AND

EXCEPT THAT PORTION CONVEYED TO THE CITY OF BELLEVUE FOR ROAD BY DEED RECORDED
UNDER RECORDING NUMBER 7712090814.

PARCEL C:

                                       1
<PAGE>

THE EAST 264 FEET OF THE SOUTH 180 FEET OF THE SOUTHWEST QUARTER OF THE
SOUTHWEST QUARTER OF THE SOUTHEAST QUARTER OF SECTION 29, TOWNSHIP 25 NORTH,
RANGE 5 EAST, WILLAMETTE MERIDIAN, IN KING COUNTY, WASHINGTON;

EXCEPT THAT PORTION THEREOF LYING EASTERLY OF A LINE THAT IS 30 FEET WEST OF THE
EAST LINE OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF THE SOUTHEAST
QUARTER OF SECTION 29; AND

EXCEPT THAT PORTION THEREOF, CONVEYED TO THE CITY OF BELLEVUE, FOR SIDEWALKS,
STREET AND UTILITIES, BY INSTRUMENT RECORDED ON AUGUST 4, 1983, UNDER RECORDING
NUMBER 8308040699.

                THE REMAINDER OF THIS PAGE IS INTENTIONALLY BLANK

                                       2
<PAGE>

                                    EXHIBIT B

                               EXPENSES AND TAXES

This Exhibit is attached to and made a part of the Lease by and between
LIGHTBRIDGE, INC., A DELAWARE CORPORATION ("Landlord") and LIGHTBRIDGE, INC., A
DELAWARE CORPORATION ("Tenant") for space in the Building located at 10800 NE
8th Street, Bellevue, Washington, commonly known as US Bank Plaza.

1. PAYMENTS.

      1.01 Tenant shall pay Tenant's Pro Rata Share of the total amount of
Expenses and Taxes for each calendar year during the Term. Landlord shall
provide Tenant with a good faith estimate of the total amount of Expenses and
Taxes for each calendar year during the Term. On or before the first day of each
month, Tenant shall pay to Landlord a monthly installment equal to one-twelfth
of Tenant's Pro Rata Share of Landlord's estimate of the total amount of
Expenses and Taxes. If Landlord determines that its good faith estimate was
incorrect by a material amount, Landlord may provide Tenant with a revised
estimate. After its receipt of the revised estimate, Tenant's monthly payments
shall be based upon the revised estimate. If Landlord does not provide Tenant
with an estimate of the total amount of Expenses and Taxes by January 1 of a
calendar year, Tenant shall continue to pay monthly installments based on the
previous year's estimate until Landlord provides Tenant with the new estimate.
Upon delivery of the new estimate, an adjustment shall be made for any month for
which Tenant paid monthly installments based on the previous year's estimate.
Tenant shall pay Landlord the amount of any underpayment within 30 days after
receipt of the new estimate. Any overpayment shall be refunded to Tenant within
30 days or credited against the next due future installment(s) of Additional
Rent. Notwithstanding anything else to the contrary contained herein, for
purposes of computing Tenant's Pro Rata Share of Expenses, the Controllable
Expenses (hereinafter defined) shall not increase by more than 5% per calendar
year on a compounding and cumulative basis over the course of the Term. In other
words, Controllable Expenses for the second calendar year of the Term shall not
exceed 105% of the Controllable Expenses for the first calendar year of the
Term. Controllable Expenses for the third calendar year of the Term shall not
exceed 105% of the limit on Controllable Expenses for the second calendar year
of the Term, etc. By way of illustration, if Controllable Expenses were $10.00
per rentable square foot for the first calendar year of the Term, then
Controllable Expenses for the second calendar year of the Term shall not exceed
$10.50 per rentable square foot, and Controllable Expenses for the third
calendar year of the Term shall not exceed $11.03 per rentable square foot.
"CONTROLLABLE EXPENSES" shall mean all Expenses exclusive of the cost of
insurance, utilities and capital improvements.

      1.02 As soon as is practical following the end of each calendar year,
Landlord shall furnish Tenant with a statement of the actual amount and Tenant's
Pro Rata Share of Expenses and Taxes for the prior calendar year. If the
estimated amount of Expenses and Taxes for the prior calendar year is more than
the actual amount of Expenses and Taxes for the prior calendar year, Landlord
shall apply any overpayment by Tenant against Additional Rent due or next
becoming due, provided if the Term expires before the determination of the
overpayment, Landlord shall refund any overpayment to Tenant after first
deducting the amount of Rent due. If the estimated amount of Expenses and Taxes
for the prior calendar year is less than the actual amount of Expenses and Taxes
for such prior year, Tenant shall pay Landlord, within 30 days after its receipt
of the statement of Expenses and Taxes, any underpayment for the prior calendar
year.

2. EXPENSES.

      2.01 "EXPENSES" means all costs and expenses incurred in each calendar
year in connection with operating, maintaining, repairing, and managing the
Building and the Property. Expenses include, without limitation: (a) all labor
and labor related costs, including wages, salaries, bonuses, taxes, insurance,
uniforms, training, retirement plans, pension plans and other employee benefits;
(b) management fees (provided that in no event shall management fees exceed 7%
of gross receipts of the Building); (c) the cost of equipping, staffing and
operating an on-site and/or off-site management office for the Building,
provided if the management office services one or more other buildings or
properties, the shared costs and expenses of equipping, staffing and operating
such management office(s) shall be equitably prorated and apportioned between
the Building and the other buildings or properties; (d) accounting costs; (e)
the cost of services; (f) rental and purchase cost of parts, supplies, tools and
equipment; provided however, if any such parts, supplies, tools or equipment
would be deemed a capital expenditure under generally accepted accounting
principles, then the

                                        1
<PAGE>

determination of whether the rental or purchase cost of such item may be
properly included in Expenses shall be governed by the terms of subsection (i)
below; (g) insurance premiums and deductibles; (h) electricity, gas and other
utility costs; and (i) the amortized cost of capital improvements (as
distinguished from replacement parts or components installed in the ordinary
course of business) which are: (1) performed primarily to reduce current or
future operating expense costs, upgrade Building security or otherwise improve
the operating efficiency of the Property; or (2) required to comply with any
Laws that are enacted, or first interpreted to apply to the Property, after the
date of this Lease. Landlord, by itself or through an affiliate, shall have the
right to directly perform or provide any services under this Lease (including
management services). However, in no event shall the management fees for the
Building exceed 7% of gross receipts for the Building. The cost of capital
improvements shall be amortized by Landlord over the lesser of the Payback
Period (defined below) or the useful life of the capital improvement as
reasonably determined by Landlord. The amortized cost of capital improvements
may, at Landlord's option, include actual or imputed interest at the rate that
Landlord would reasonably be required to pay to finance the cost of the capital
improvement. "PAYBACK PERIOD" means the reasonably estimated period of time that
it takes for the cost savings resulting from a capital improvement to equal the
total cost of the capital improvement. Landlord, by itself or through an
affiliate, shall have the right to directly perform, provide and be compensated
for any services under this Lease (subject to Section 2.02). If Landlord incurs
Expenses for the Building or Property together with one or more other buildings
or properties, whether pursuant to a reciprocal easement agreement, common area
agreement or otherwise, the shared costs and expenses shall be equitably
prorated and apportioned between the Building and Property and the other
buildings or properties.

      2.02 Expenses shall not include: the cost of capital improvements (except
as set forth above); depreciation; principal payments of mortgage and other
non-operating debts of Landlord; the cost of repairs or other work to the extent
Landlord is reimbursed (or would have been reimbursed had Landlord maintained
the required insurance hereunder) by insurance or condemnation proceeds; costs
in connection with leasing space in the Building, including brokerage
commissions; lease concessions, rental abatements, construction allowances
granted to specific tenants and costs in preparing space in the Building for
initial occupancy by a specific tenant; costs incurred in connection with the
sale, financing or refinancing of the Building; fines, interest and penalties
incurred due to the late payment of Taxes or Expenses or to Landlord's violation
of any applicable Law; organizational expenses associated with the creation and
operation of the entity which constitutes Landlord; or any penalties or damages
that Landlord pays to Tenant under this Lease or to other tenants in the
Building under their respective leases. The following items are also excluded
from Expenses: (a) sums (other than management fees, it being agreed that the
management fees included in Expenses are as described in Section 2.01 above)
paid to subsidiaries or other affiliates of Landlord for services on or to the
Property, Building and/or Premises, but only to the extent that the costs of
such services exceed the competitive cost for such services rendered by persons
or entities of similar skill, competence and experience, (b) any costs, fines,
penalties or interest resulting from the negligence or willful misconduct of the
Landlord or its agents, contractors, or employees, (c) advertising and
promotional expenditures, (d) ground lease rental, (e) attorney's fees and other
expenses incurred in connection with negotiations or disputes with prospective
tenants or tenants or other occupants of the Building, (g) the cost or expense
of any services or benefits provided generally to other tenants in the Building
and not provided or available to Tenant, and (h) expenses for the replacement of
any item covered under warranty, unless Landlord has not received payment under
such warranty and it would not be fiscally prudent to pursue legal action to
collect on such warranty.

      2.03 If the Building is not at least 95% occupied during any calendar year
or if Landlord is not supplying services to at least 95% of the total Rentable
Square Footage of the Building at any time during a calendar year, Expenses
shall, at Landlord's option, be determined as if the Building had been 95%
occupied and Landlord had been supplying services to 95% of the Rentable Square
Footage of the Building during that calendar year. Notwithstanding the
foregoing, Landlord may calculate the extrapolation of Expenses under this
Section based on 100% occupancy and service so long as such percentage is used
consistently for each year of the Term. The extrapolation of Expenses under this
Section shall be performed in accordance with the methodology specified by the
Building Owners and Managers Association.

3. "TAXES" shall mean: (a) all real property taxes and other assessments on the
Building and/or Property, including, but not limited to, gross receipts taxes,
assessments for special improvement districts and building improvement
districts, governmental charges, fees and assessments for police, fire, traffic
mitigation or other governmental service of purported benefit to the Property,
taxes and assessments levied in substitution or supplementation in whole or in
part of any such taxes and assessments and the Property's share of any real
estate taxes and assessments under any reciprocal easement agreement, common
area agreement or similar

                                       2
<PAGE>

agreement as to the Property; (b) all personal property taxes for property that
is owned by Landlord and used in connection with the operation, maintenance and
repair of the Property; and (c) all reasonable costs and fees incurred in
connection with seeking reductions in any tax liabilities described in (a) and
(b), including, without limitation, any costs incurred by Landlord for
compliance, review and appeal of tax liabilities. Without limitation, Taxes
shall not include any income, capital levy, transfer, capital stock, gift,
estate or inheritance tax. If a change in Taxes is obtained for any year of the
Term during which Tenant paid Tenant's Pro Rata Share of any Tax Excess, then
Taxes for that year will be retroactively adjusted and Landlord shall provide
Tenant with a credit, if any, against Rent, based on the adjustment, or if the
Term shall have ended, promptly refund the excess to Tenant. Tenant shall pay
Landlord the amount of Tenant's Pro Rata Share of any such increase in the Tax
Excess within 30 days after Tenant's receipt of a statement from Landlord.

4. AUDIT RIGHTS. Tenant, within 365 days after receiving Landlord's statement of
Expenses, may give Landlord written notice ("REVIEW NOTICE") that Tenant intends
to review Landlord's records of the Expenses for that calendar year to which the
statement applies. Within a reasonable time after receipt of the Review Notice,
Landlord shall make all pertinent records available for inspection that are
reasonably necessary for Tenant to conduct its review. If any records are
maintained at a location other than the management office for the Building,
Tenant may either inspect the records at such other location or pay for the
reasonable cost of copying and shipping the records. If Tenant retains an agent
to review Landlord's records, the agent must be with a CPA firm licensed to do
business in the state or commonwealth where the Property is located. Tenant
shall be solely responsible for all costs, expenses and fees incurred for the
audit. Within 90 days after the records are made available to Tenant, Tenant
shall have the right to give Landlord written notice (an "OBJECTION NOTICE")
stating in reasonable detail any objection to Landlord's statement of Expenses
for that year. If Tenant fails to give Landlord an Objection Notice within the
90 day period or fails to provide Landlord with a Review Notice within the 365
day period described above, Tenant shall be deemed to have approved Landlord's
statement of Expenses and shall be barred from raising any claims regarding the
Expenses for that year. If Tenant provides Landlord with a timely Objection
Notice, Landlord and Tenant shall work together in good faith to resolve any
issues raised in Tenant's Objection Notice. If Landlord and Tenant determine
that Expenses for the calendar year are less than reported, Landlord shall
provide Tenant with a credit against the next installment of Rent in the amount
of the overpayment by Tenant, or, if no Rent is thereafter due, Landlord shall
promptly pay such amount to Tenant. In addition, if Landlord and Tenant
determine that Landlord's statement of Expenses for the Building for the
calendar year in question were overstated by five percent (5%) or more, Landlord
shall be required to reimburse Tenant for any reasonable third party audit costs
incurred by Tenant. Likewise, if Landlord and Tenant determine that Expenses for
the calendar year are greater than reported, Tenant shall pay Landlord the
amount of any underpayment within 30 days. The records obtained by Tenant shall
be treated as confidential. In no event shall Tenant be permitted to examine
Landlord's records or to dispute any statement of Expenses unless Tenant has
paid and continues to pay all Rent when due.

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                                       3
<PAGE>

                                    EXHIBIT C

                                   WORK LETTER

      This Exhibit is attached to and made a part of the Lease by and between
LIGHTBRIDGE, INC., A DELAWARE CORPORATION ("Landlord") and LIGHTBRIDGE, INC., A
DELAWARE CORPORATION ("Tenant") for space in the Building located at 10800 NE
8th Street, Bellevue, Washington, commonly known as US Bank Plaza.

As used in this Work Letter, the "PREMISES" shall be deemed to mean the
Premises, as initially defined in the attached Lease.

1.    Landlord shall perform improvements to the Premises substantially in
      accordance with the plans prepared by Burgess Design, Inc., a Washington
      corporation ("LANDLORD'S ARCHITECT"), dated June 3, 2004 (the "PLANS").
      The improvements to be performed by Landlord in accordance with the Plans
      are hereinafter referred to as the "LANDLORD WORK." It is agreed that
      construction of the Landlord Work will be completed at Landlord's sole
      cost and expense (subject to the Maximum Amount and further subject to the
      terms of Paragraph 4 below) using Building standard methods, materials and
      finishes. Landlord and Tenant agree that Landlord's obligation to pay for
      the cost of Landlord Work (inclusive of the cost of preparing Plans,
      obtaining permits, a construction management fee equal to 5% of the total
      construction costs, and other related costs) shall be limited to
      $176,850.00 (the "MAXIMUM AMOUNT") and that Tenant shall be responsible
      for the cost of Landlord Work, plus any applicable state sales or use tax,
      if any, to the extent that it exceeds the Maximum Amount. Landlord shall
      enter into a direct contract for the Landlord Work with a general
      contractor selected by Landlord. In addition, Landlord shall have the
      right to select and/or approve of any subcontractors used in connection
      with the Landlord Work. Landlord's supervision or performance of any work
      for or on behalf of Tenant shall not be deemed a representation by
      Landlord that such Plans or the revisions thereto comply with applicable
      insurance requirements, building codes, ordinances, laws or regulations,
      or that the improvements constructed in accordance with the Plans and any
      revisions thereto will be adequate for Tenant's use, it being agreed that
      Tenant shall be responsible for all elements of the design of Tenant's
      plans (including, without limitation, compliance with law, functionality
      of design, the structural integrity of the design, the configuration of
      the premises and the placement of Tenant's furniture, appliances and
      equipment). Notwithstanding the foregoing or any other provision of the
      Lease to the contrary, if the design of the Plans contains any material
      defect, then Landlord shall not, without Tenant's prior written consent
      (which may be withheld in Tenant's sole and absolute discretion), waive
      any claims Landlord may have against Landlord's Architect under the
      Architect Agreement (defined below) arising out of such defect, and, upon
      written notice and request from Tenant, Landlord shall, at its option,
      either (a) assign such claims to Tenant, or (b) pursue such claims
      directly against Landlord's Architect for Tenant's benefit (provided that
      Tenant shall pay all reasonable out-of-pocket expenses, including
      attorneys' fees and costs, incurred by Landlord in pursuing such claims).
      As used herein, "ARCHITECT AGREEMENT" shall mean that certain Agreement
      Between Owner and Architect, and that certain Addendum to Agreement
      Between Owner and Architect, each dated as of July 21, 2004, between
      Landlord and Landlord's Architect, pursuant to which the Plans were
      prepared.

2.    If Landlord's estimate and/or the actual cost of the Landlord Work shall
      exceed the Maximum Amount, Landlord, prior to commencing any construction
      of Landlord Work, shall submit to Tenant a written estimate setting forth
      the anticipated cost of the Landlord Work, including but not limited to
      labor and materials, contractor's fees and permit fees. Within 3 Business
      Days thereafter, Tenant shall either notify Landlord in writing of its
      approval of the cost estimate, or specify its objections thereto and any
      desired changes to the proposed Landlord Work. If Tenant notifies Landlord
      of such objections and desired changes, Tenant shall work with Landlord to
      reach a mutually acceptable alternative cost estimate.

3.    If Landlord's estimate and/or the actual cost of construction shall exceed
      the Maximum Amount (such amounts exceeding the Maximum Amount being herein
      referred to as the "EXCESS COSTS"), Tenant shall pay to Landlord such
      Excess Costs, plus any applicable state sales or use tax thereon, upon
      demand. The statements of costs submitted to Landlord by Landlord's
      contractors shall be conclusive for purposes of determining the actual
      cost of the items described therein. The amounts payable by Tenant
      hereunder

                                       1
<PAGE>

      constitute Rent payable pursuant to the Lease, and the failure to timely
      pay same constitutes an event of default under the Lease. In the event
      that Landlord's estimate exceeds the actual costs of construction,
      Landlord shall pay to Tenant, promptly after Landlord's receipt, review
      and approval of all invoices, any Excess Costs paid by Tenant I excess of
      the actual costs of construction.

4.    If Tenant shall request any revisions to the Plans, Landlord shall have
      such revisions prepared at Tenant's sole cost and expense and Tenant shall
      reimburse Landlord for the cost of preparing any such revisions to the
      Plans, plus any applicable state sales or use tax thereon, upon demand.
      Promptly upon completion of the revisions, Landlord shall notify Tenant in
      writing of the increased cost in the Landlord Work, if any, resulting from
      such revisions to the Plans. Tenant, within one Business Day, shall notify
      Landlord in writing whether it desires to proceed with such revisions. In
      the absence of such written authorization, Landlord shall have the option
      to continue work on the Premises disregarding the requested revision.
      Tenant shall be responsible for any Tenant Delay in completion of the
      Premises resulting from any revision to the Plans. If such revisions
      result in an increase in the cost of Landlord Work, such increased costs,
      plus any applicable state sales or use tax thereon, shall be payable by
      Tenant upon demand. Notwithstanding anything herein to the contrary, all
      revisions to the Plans shall be subject to the approval of Landlord.

5.    Any portion of the Maximum Amount which exceeds the cost of the Landlord
      Work or is otherwise remaining after December 31, 2004, shall accrue to
      the sole benefit of Landlord, it being agreed that Tenant shall not be
      entitled to any credit, offset, abatement or payment with respect thereto.

6.    This Exhibit shall not be deemed applicable to any additional space added
      to the Premises at any time or from time to time, whether by any options
      under the Lease or otherwise, or to any portion of the original Premises
      or any additions to the Premises in the event of a renewal or extension of
      the original Term of the Lease, whether by any options under the Lease or
      otherwise, unless expressly so provided in the Lease or any amendment or
      supplement to the Lease.

                THE REMAINDER OF THIS PAGE IS INTENTIONALLY BLANK

                                       2
<PAGE>

                                   EXHIBIT C-1

                           MUST TAKE SPACE WORK LETTER

      This Exhibit is attached to and made a part of the Lease by and between
LIGHTBRIDGE, INC., A DELAWARE CORPORATION ("Landlord") and LIGHTBRIDGE, INC., A
DELAWARE CORPORATION ("Tenant") for space in the Building located at 10800 NE
8th Street, Bellevue, Washington, commonly known as US Bank Plaza.

As used in this Must Take Space Work Letter, the "PREMISES" shall be deemed to
mean the Must-Take Space, as defined in Section I.A. of EXHIBIT F attached to
this Lease.

I.    ALTERATIONS AND ALLOWANCE.

      A.    Tenant, following the delivery of the Premises by Landlord and the
            full and final execution and delivery of the Lease to which this
            Exhibit is attached and all prepaid rental and security deposits
            required under such agreement, shall have the right to perform
            alterations and improvements in the Premises (the "INITIAL
            ALTERATIONS"). Notwithstanding the foregoing, Tenant and its
            contractors shall not have the right to perform Initial Alterations
            in the Premises unless and until Tenant has complied with all of the
            terms and conditions of Section 9 of the Lease, including, without
            limitation, approval by Landlord of the final plans for the Initial
            Alterations and the contractors to be retained by Tenant to perform
            such Initial Alterations. Tenant shall be responsible for all
            elements of the design of Tenant's plans (including, without
            limitation, compliance with law, functionality of design, the
            structural integrity of the design, the configuration of the
            premises and the placement of Tenant's furniture, appliances and
            equipment), and Landlord's approval of Tenant's plans shall in no
            event relieve Tenant of the responsibility for such design.
            Landlord's approval of the contractors to perform the Initial
            Alterations shall not be unreasonably withheld or delayed. The
            parties agree that Landlord's approval of the general contractor to
            perform the Initial Alterations shall not be considered to be
            unreasonably withheld if any such general contractor (i) is not on
            Landlord's list of contractors approved to perform work in the
            Premises, (ii) does not have trade references reasonably acceptable
            to Landlord, (iii) does not maintain insurance as required pursuant
            to the terms of this Lease, (iv) does not have the ability to be
            bonded for the work in an amount of no less than 150% of the total
            estimated cost of the Initial Alterations, (v) does not provide
            current financial statements reasonably acceptable to Landlord, or
            (vi) is not licensed as a contractor in the state/municipality in
            which the Premises is located. Tenant acknowledges the foregoing is
            not intended to be an exclusive list of the reasons why Landlord may
            reasonably withhold its consent to a general contractor.

      B.    Provided Tenant is not in default, Landlord agrees to contribute the
            sum of $52,607.87 (i.e., $10.63 per rentable square foot of the
            Premises) (the "ALLOWANCE") toward the cost of performing the
            Initial Alterations in preparation of Tenant's occupancy of the
            Premises. The Allowance may only be used for hard costs in
            connection with the Initial Alterations, including the cost of
            purchasing and installing any telephone and computer cabling in the
            Premises up to a maximum amount of $12,372.50 (i.e., $2.50 per
            rentable square foot of the Premises), but excluding any other cost
            of purchasing or installing telephone or computer cabling. The
            Allowance shall be paid to Tenant or, at Landlord's option, to the
            order of the general contractor that performed the Initial
            Alterations, within 30 days following receipt by Landlord of (1)
            receipted bills covering all labor and materials expended and used
            in the Initial Alterations; (2) a sworn contractor's affidavit from
            the general contractor and a request to disburse from Tenant
            containing an approval by Tenant of the work done; (3) full and
            final waivers of lien; (4) as-built plans of the Initial
            Alterations; and (5) the certification of Tenant and its architect
            that the Initial Alterations have been installed in a good and
            workmanlike manner in accordance with the approved plans, and in
            accordance with applicable laws, codes and ordinances. The Allowance
            shall be disbursed in the amount reflected on the receipted bills
            meeting the requirements above. Notwithstanding anything herein to
            the contrary, Landlord shall not be obligated to disburse any
            portion of the Allowance during the continuance of a Default under
            the Lease, and Landlord's obligation to disburse shall only resume
            when and if such Default is cured.

                                       1
<PAGE>

      C.    In no event shall the Allowance be used for the purchase of
            equipment, furniture or other items of personal property of Tenant.
            If Tenant does not submit a request for payment of the entire
            Allowance to Landlord in accordance with the provisions contained in
            this Exhibit by (a) December 15, 2005, or (b) eight (8) months from
            the Must-Take Commencement Date, if the Must-Take Commencement Date
            is delayed pursuant to Section I.A. of Exhibit F, any unused amount
            shall accrue to the sole benefit of Landlord, it being understood
            that Tenant shall not be entitled to any credit, abatement or other
            concession in connection therewith. Tenant shall be responsible for
            all applicable state sales or use taxes, if any, payable in
            connection with the Initial Alterations and/or Allowance. Landlord
            shall be entitled to deduct from the Allowance a construction
            management fee for Landlord's oversight of the Initial Alterations
            in an amount equal to 5% of the total cost of the Initial
            Alterations.

      D.    Tenant agrees to accept the Premises in its "as-is" condition and
            configuration, it being agreed that Landlord shall not be required
            to perform any work or, except as provided above with respect to the
            Allowance, incur any costs in connection with the construction or
            demolition of any improvements in the Premises.

      E.    This Exhibit shall not be deemed applicable to any additional space
            added to the Premises at any time or from time to time, whether by
            any options under the Lease or otherwise, or to any portion of the
            original Premises or any additions to the Premises in the event of a
            renewal or extension of the original Term of the Lease, whether by
            any options under the Lease or otherwise, unless expressly so
            provided in the Lease or any amendment or supplement to the Lease.

                THE REMAINDER OF THIS PAGE IS INTENTIONALLY BLANK

                                        2
<PAGE>

                                    EXHIBIT D

                               COMMENCEMENT LETTER
                                    (EXAMPLE)

Date

Tenant
Address

Re:   Commencement Letter with respect to that certain Lease dated as of the
      _____ day of ____________, 2004, by and between LIGHTBRIDGE, INC., A
      DELAWARE CORPORATION, as Landlord, and LIGHTBRIDGE, INC., A DELAWARE
      CORPORATION, as Tenant, for 14,148 rentable square feet on the 6th floor
      of the Building located at 10800 NE 8th Street, Bellevue, Washington,
      commonly known as US Bank Plaza.

Dear  __________________:

      In accordance with the terms and conditions of the above referenced Lease,
Tenant accepts possession of the Premises and agrees:

      1.    The Commencement Date of the Lease is ________________________;

      2.    The Termination Date of the Lease is _________________________.

      Please acknowledge your acceptance of possession and agreement to the
terms set forth above by signing all 3 counterparts of this Commencement Letter
in the space provided and returning 2 fully executed counterparts to my
attention.

Sincerely,

____________________________________
Authorized Signatory

Agreed and Accepted:

      Tenant: LIGHTBRIDGE, INC., A DELAWARE CORPORATION

      By:     ______________________
      Name:   ______________________
      Title:  ______________________
      Date:   ______________________

                                       1
<PAGE>

                                    EXHIBIT E

                         BUILDING RULES AND REGULATIONS

      The following rules and regulations shall apply, where applicable, to the
Premises, the Building, the parking facilities (if any), the Property and the
appurtenances. In the event of a conflict between the following rules and
regulations and the remainder of the terms of the Lease, the remainder of the
terms of the Lease shall control. Capitalized terms have the same meaning as
defined in the Lease.

1.    Sidewalks, doorways, vestibules, halls, stairways and other similar areas
      shall not be obstructed by Tenant or used by Tenant for any purpose other
      than ingress and egress to and from the Premises. No rubbish, litter,
      trash, or material shall be placed, emptied, or thrown in those areas. At
      no time shall Tenant permit Tenant's employees to loiter in Common Areas
      or elsewhere about the Building or Property.

2.    Plumbing fixtures and appliances shall be used only for the purposes for
      which designed and no sweepings, rubbish, rags or other unsuitable
      material shall be thrown or placed in the fixtures or appliances. Damage
      resulting to fixtures or appliances by Tenant, its agents, employees or
      invitees shall be paid for by Tenant and Landlord shall not be responsible
      for the damage.

3.    No signs, advertisements or notices shall be painted or affixed to
      windows, doors or other parts of the Building, except those of such color,
      size, style and in such places as are first approved in writing by
      Landlord. All tenant identification and suite numbers at the entrance to
      the Premises shall be installed by Landlord, at Tenant's cost and expense,
      using the standard graphics for the Building. Notwithstanding the
      foregoing, Landlord shall install initial Tenant identification and suite
      numbers at the entrance to the Premises, and initial Tenant identification
      on the Building directory and outside monument signage, as described in
      Section 4 below at Landlord's cost and expense. Except in connection with
      the hanging of lightweight pictures and wall decorations, no nails, hooks
      or screws shall be inserted into any part of the Premises or Building
      except by the Building maintenance personnel without Landlord's prior
      approval, which approval shall not be unreasonably withheld.

4.    Landlord shall provide and maintain, at Landlord's expense, in the first
      floor (main lobby) of the Building an alphabetical directory board or
      other directory device listing tenants and no other directory shall be
      permitted unless previously consented to by Landlord in writing. In
      addition, Landlord shall provide and maintain, at Landlord's expense, a
      monument sign outside the Building listing Building tenants.

5.    Tenant shall not place any lock(s) on any door in the Premises or Building
      without Landlord's prior written consent, which consent shall not be
      unreasonably withheld, and Landlord shall have the right at all times to
      retain and use keys or other access codes or devices to all locks within
      and into the Premises. A reasonable number of keys to the locks on the
      entry doors in the Premises shall be furnished by Landlord to Tenant at
      Tenant's cost and Tenant shall not make any duplicate keys. All keys shall
      be returned to Landlord at the expiration or early termination of the
      Lease.

6.    All contractors, contractor's representatives and installation technicians
      performing work in the Building shall be subject to Landlord's prior
      approval, which approval shall not be unreasonably withheld, and shall be
      required to comply with Landlord's standard rules, regulations, policies
      and procedures, which may be revised from time to time.

7.    Movement in or out of the Building of furniture or office equipment, or
      dispatch or receipt by Tenant of merchandise or materials requiring the
      use of elevators, stairways, lobby areas or loading dock areas, shall be
      restricted to hours reasonably designated by Landlord. Tenant shall obtain
      Landlord's prior approval by providing a detailed listing of the activity,
      which approval shall not be unreasonably withheld. If approved by
      Landlord, the activity shall be under the supervision of Landlord and
      performed in the manner required by Landlord. Tenant shall assume all risk
      for damage to articles moved and injury to any persons resulting from the
      activity. If equipment, property, or personnel of Landlord or of any other
      party is damaged or injured as a result of or in connection with the
      activity, Tenant shall be solely liable for any resulting damage, loss or
      injury.

8.    Landlord shall have the right to approve the weight, size, or location of
      heavy equipment or articles in and about the Premises, which approval
      shall not be unreasonably

                                       1
<PAGE>

      withheld. Damage to the Building by the installation, maintenance,
      operation, existence or removal of Tenant's Property shall be repaired at
      Tenant's sole expense.

9.    Corridor doors, when not in use, shall be kept closed.

10.   Tenant shall not: (1) make or permit any improper, objectionable or
      unpleasant noises or odors in the Building, or otherwise interfere in any
      way with other tenants or persons having business with them; (2) solicit
      business or distribute or cause to be distributed, in any portion of the
      Building, handbills, promotional materials or other advertising; or (3)
      conduct or permit other activities in the Building that might, in
      Landlord's sole opinion, constitute a nuisance.

11.   No animals, except those assisting handicapped persons, shall be brought
      into the Building or kept in or about the Premises.

12.   No inflammable, explosive or dangerous fluids or substances shall be used
      or kept by Tenant in the Premises, Building or about the Property, except
      for those substances as are typically found in similar premises used for
      general office purposes and are being used by Tenant in a safe manner and
      in accordance with all applicable Laws. Tenant shall not, without
      Landlord's prior written consent, use, store, install, spill, remove,
      release or dispose of, within or about the Premises or any other portion
      of the Property, any asbestos-containing materials or any solid, liquid or
      gaseous material now or subsequently considered toxic or hazardous under
      the provisions of 42 U.S.C. Section 9601 et seq. or any other applicable
      environmental Law which may now or later be in effect. Tenant shall comply
      with all Laws pertaining to and governing the use of these materials by
      Tenant and shall remain solely liable for the costs of abatement and
      removal.

13.   Tenant shall not use or occupy the Premises in any manner or for any
      purpose which might injure the reputation or impair the present or future
      value of the Premises or the Building. Tenant shall not use, or permit any
      part of the Premises to be used for lodging, sleeping or for any illegal
      purpose.

14.   Tenant shall not take any action which would violate Landlord's labor
      contracts or which would cause a work stoppage, picketing, labor
      disruption or dispute or interfere with Landlord's or any other tenant's
      or occupant's business or with the rights and privileges of any person
      lawfully in the Building ("LABOR DISRUPTION"). Tenant shall take the
      actions necessary to resolve the Labor Disruption, and shall have pickets
      removed and, at the request of Landlord, immediately terminate any work in
      the Premises that gave rise to the Labor Disruption, until Landlord gives
      its written consent for the work to resume. Tenant shall have no claim for
      damages against Landlord or any of the Landlord Related Parties nor shall
      the Commencement Date of the Term be extended as a result of the above
      actions.

15.   Tenant shall not install, operate or maintain in the Premises or in any
      other area of the Building, electrical equipment that would overload the
      electrical system beyond its capacity for proper, efficient and safe
      operation as determined solely by Landlord. Tenant shall not furnish
      cooling or heating to the Premises, including, without limitation, the use
      of electric or gas heating devices, without Landlord's prior written
      consent. Tenant shall not use more than its proportionate share of
      telephone lines and other telecommunication facilities available to
      service the Building.

16.   Tenant shall not operate or permit to be operated a coin or token operated
      vending machine or similar device (including, without limitation,
      telephones, lockers, toilets, scales, amusement devices and machines for
      sale of beverages, foods, candy, cigarettes and other goods), except for
      machines for the exclusive use of Tenant's employees and invitees.

17.   Bicycles and other vehicles are not permitted inside the Building or on
      the walkways outside the Building, except in areas designated by Landlord.

18.   Landlord may from time to time adopt systems and procedures for the
      security and safety of the Building and Property, its occupants, entry,
      use and contents. Tenant, its agents, employees, contractors, guests and
      invitees shall comply with Landlord's systems and procedures.

                                       2
<PAGE>

19.   Landlord shall have the right to prohibit the use of the name of the
      Building or any other publicity by Tenant that in Landlord's sole opinion
      may impair the reputation of the Building or its desirability. Upon
      written notice from Landlord, Tenant shall refrain from and discontinue
      such publicity immediately.

20.   Neither Tenant nor its agents, employees, contractors, guests or invitees
      shall smoke or permit smoking in the Common Areas, unless a portion of the
      Common Areas have been declared a designated smoking area by Landlord, nor
      shall the above parties allow smoke from the Premises to emanate into the
      Common Areas or any other part of the Building. Landlord shall have the
      right to designate the Building (including the Premises) as a non-smoking
      building.

21.   Landlord shall have the right to designate and approve standard window
      coverings for the Premises and to establish rules to assure that the
      Building presents a uniform exterior appearance. Tenant shall ensure, to
      the extent reasonably practicable, that window coverings are closed on
      windows in the Premises while they are exposed to the direct rays of the
      sun.

22.   Deliveries to and from the Premises shall be made only at the times in the
      areas and through the entrances and exits reasonably designated by
      Landlord. Tenant shall not make deliveries to or from the Premises in a
      manner that might interfere with the use by any other tenant of its
      premises or of the Common Areas, any pedestrian use, or any use which is
      inconsistent with good business practice.

23.   The work of cleaning personnel shall not be hindered by Tenant after 5:30
      P.M., and cleaning work may be done at any time when the offices are
      vacant. Windows, doors and fixtures may be cleaned at any time. Tenant
      shall provide adequate waste and rubbish receptacles to prevent
      unreasonable hardship to the cleaning service.

                                       3
<PAGE>

                                    EXHIBIT F

                              ADDITIONAL PROVISIONS

      This Exhibit is attached to and made a part of the Lease by and between
LIGHTBRIDGE, INC., A DELAWARE CORPORATION ("Landlord") and LIGHTBRIDGE, INC., A
DELAWARE CORPORATION ("Tenant") for space in the Building located at 10800 NE
8th Street, Bellevue, Washington, commonly known as US Bank Plaza.

I.    MUST TAKE SPACE.

      A.    Tenant hereby leases from Landlord and Landlord hereby leases to
            Tenant the 4,949 square feet of rentable area described as Suite No.
            310 on the 3rd floor of the Building and shown on EXHIBIT A-1
            attached hereto (the "MUST-TAKE SPACE"). The Term with respect to
            the Must-Take Space shall commence on May 1, 2005 (the "MUST-TAKE
            SPACE COMMENCEMENT DATE") and, unless terminated early in accordance
            with the Lease, end on the Termination Date, as determined in
            accordance with Section 3.01 of the Lease. The period commencing on
            the Must-Take Space Commencement Date and ending on the Termination
            Date is hereinafter referred to herein as the "MUST-TAKE SPACE
            TERM". Effective as of the Must-Take Space Commencement Date, the
            Must-Take Space shall be deemed to be a part of the Premises.
            Notwithstanding the foregoing to the contrary, the Must-Take Space
            Commencement Date shall be delayed to the extent that Landlord fails
            to deliver possession of the Must-Take Space for any reason,
            including but not limited to, holding over by prior occupants, in
            which event, the Must-Take Space Commencement Date shall instead be
            the date on which Landlord tenders delivery of the Must-Take Space
            to Tenant. However, any delay in the Must-Take Space Commencement
            Date shall not subject Landlord to any liability for any loss or
            damage resulting therefrom. If the Must-Take Space Commencement Date
            is delayed, the Termination Date under the Lease shall not be
            similarly extended.

      B.    The Must-Take Space is leased by Tenant pursuant to all of the terms
            and conditions of the Lease, except that the financial terms and
            conditions (i.e., Base Rent, Additional Rent) for the Must-Take
            Space shall be as follows:

            1.    Tenant shall pay Landlord Base Rent for the Must-Take Space as
                  follows:

<TABLE>
<CAPTION>
                               ANNUAL RATE       MONTHLY
        PERIOD               PER SQUARE FOOT    BASE RENT
-----------------------      ---------------    ---------
<S>                          <C>                <C>
5/1/05 through 9/30/05           $11.75         $4,845.90
10/1/05 through 9/30/06          $12.25         $5,052.10
10/1/06 through 9/30/07          $12.75         $5,258.31
10/1/07 through 9/30/08          $13.25         $5,464.52
10/1/08 through 9/30/09          $13.75         $5,670.73
</TABLE>

            2.    Effective as of the Must-Take Space Commencement Date, Tenant
                  shall pay Additional Rent (i.e. Expenses and Taxes) for the
                  Must-Take Space on the same terms and conditions set forth in
                  Section 4 of the Lease, provided that effective as of the
                  Must-Take Space Commencement Date, Tenant's Pro Rata Share
                  shall increase by 3.6026% to account for the addition of the
                  Must-Take Space (and from and after the Must-Take Space
                  Commencement Date, Tenant's Pro Rata Share is therefore
                  increased to 13.9016%).

            3.    Notwithstanding any of the foregoing to the contrary, if
                  Tenant takes possession of the Must-Take Space prior to the
                  Must-Take Space Commencement Date for any reason whatsoever
                  (other than the performance of work (including, planning
                  and/or performance of improvements, installation of furniture,
                  equipment or other personal property) in the Must-Take Space
                  with Landlord's prior approval), such possession shall be
                  subject to all the terms and conditions of this Lease,
                  including Section 3.02, and Tenant shall pay Base Rent and
                  Additional Rent as applicable to the Must-Take Space to
                  Landlord on a per diem basis for each day of occupancy prior
                  to the Must-Take Space Commencement Date.

                                       1
<PAGE>

            4.    Improvements to Must-Take Space.

                  a.    Tenant has inspected the Must-Take Space and agrees to
                        accept the same "as is" without any agreements,
                        representations, understandings or obligations on the
                        part of Landlord to perform any alterations, repairs or
                        improvements.

                  b.    Tenant may perform improvements to the Expansion Space
                        in accordance with the Work Letter attached hereto as
                        EXHIBIT C-1 and Tenant shall be entitled to an
                        improvement allowance in connection with such work as
                        more fully described in EXHIBIT C-1.

II.   PARKING.

      A.    During the Term, Landlord shall lease to Tenant, or cause the
            operator (the "OPERATOR") of the garage servicing the Building (the
            "GARAGE") to lease to Tenant, and Tenant shall lease from Landlord
            or such Operator, a maximum of the Applicable Number (as defined
            below ) of unreserved parking spaces in the Garage (the "SPACES")
            for the use of Tenant and its employees. The "APPLICABLE NUMBER"
            shall mean (a) 42 during the period beginning on the Commencement
            Date through the date immediately preceding the Must-Take Space
            Commencement Date (i.e. May 1, 2005), and (b) 57 during the period
            beginning on the Must-Take Space Commencement Date (i.e. May 1,
            2005) through the remainder of the Term. The Spaces shall be leased
            at the then current rate for parking in the Garage, plus applicable
            tax thereon, as such rate may be adjusted from time to time.
            Notwithstanding the foregoing, however, the following rates shall
            apply during the initial Term: (a) during the period beginning on
            the Commencement Date and ending on the last day of the 12th full
            calendar month of the Term, the Spaces shall be leased at the rate
            of $25.00 per Space, per month, plus applicable tax thereon, (b)
            during the period beginning on the first day of the 13th full
            calendar month of the Term and ending on the last day of the 36th
            full calendar month of the Term, the Spaces shall be leased at the
            rate of $50.00 per Space, per month, plus applicable tax thereon,
            and (c) during the period beginning on the first day of the 37th
            full calendar month of the Term and ending on the last day of the
            Termination Date, the Spaces shall be leased at the rate of $75.00
            per Space, per month, plus applicable tax thereon. If requested by
            Landlord, Tenant shall execute and deliver to Landlord the standard
            parking agreement used by Landlord or the Operator (the "PARKING
            AGREEMENT") in the Garage for such Spaces. Tenant shall have the
            right, by 30 days written notice to Landlord, to surrender one or
            more of the Spaces, from time to time during the Term, whereupon
            Tenant shall have no further obligation or rights with respect to
            such surrendered Space(s) arising after the effective date of
            surrender set forth in Tenant's notice.

      B.    No deductions or allowances shall be made for days when Tenant or
            any of its employees does not utilize the parking facilities or for
            Tenant utilizing less than all of the Spaces. Tenant shall not have
            the right to lease or otherwise use more than the number of reserved
            and unreserved Spaces set forth above.

      C.    Except for particular spaces and areas designated by Landlord or the
            Operator for reserved parking, all parking in the Garage shall be on
            an unreserved, first-come, first-served basis.

      D.    Neither Landlord nor the Operator shall be responsible for money,
            jewelry, automobiles or other personal property lost in or stolen
            from the Garage or the surface parking areas regardless of whether
            such loss or theft occurs when the Garage or other areas therein are
            locked or otherwise secured. Except as caused by the negligence or
            willful misconduct of Landlord and without limiting the terms of the
            preceding sentence, Landlord shall not be liable for any loss,
            injury or damage to persons using the Garage or the surface parking
            areas or automobiles or other property therein, it being agreed
            that, to the fullest extent permitted by law, the use of the Spaces
            shall be at the sole risk of Tenant and its employees.

      E.    Landlord or its Operator shall have the right from time to time to
            designate the location of the Spaces and to promulgate reasonable
            rules and regulations regarding the Garage, the surface parking
            areas, the Spaces and the use thereof, including, but not limited
            to, rules and regulations controlling the flow of

                                       2
<PAGE>

            traffic to and from various parking areas, the angle and direction
            of parking and the like. Tenant shall comply with and cause its
            employees to comply with all such rules and regulations, all
            reasonable additions and amendments thereto, and the terms and
            provisions of the Parking Agreement.

      F.    Tenant shall not store or permit its employees to store any
            automobiles in the Garage or on the surface parking areas without
            the prior written consent of Landlord. Except for emergency repairs,
            Tenant and its employees shall not perform any work on any
            automobiles while located in the Garage or on the Property. If it is
            necessary for Tenant or its employees to leave an automobile in the
            Garage or on the surface parking areas overnight, Tenant shall
            provide Landlord with prior notice thereof designating the license
            plate number and model of such automobile.

      G.    Landlord or the Operator shall have the right to temporarily close
            the Garage or certain areas therein in order to perform necessary
            repairs, maintenance and improvements to the Garage or the surface
            parking areas.

      H.    Except in connection with a Permitted Transfer or other Transfer
            consented to by Landlord pursuant to Section 11 of the lease: (1)
            Tenant shall not assign or sublease any of the Spaces without the
            consent of Landlord, and (2) Landlord shall have the right to
            terminate the agreement contained in this Section II or in the
            Parking Agreement with respect to any Spaces that Tenant desires to
            sublet or assign.

      I.    Landlord may elect to provide parking cards or keys to control
            access to the Garage or surface parking areas. In such event,
            Landlord shall provide Tenant with one card or key for each Space
            that Tenant is leasing hereunder, provided that Landlord shall have
            the right to require Tenant or its employees to place a deposit on
            such access cards or keys and to pay a fee for any lost or damaged
            cards or keys.

III.  RENEWAL OPTION.

      A.    Grant of Option; Conditions. Tenant shall have the right to extend
            the Term (the "RENEWAL OPTION") for one additional period of 5 years
            commencing on the day following the Termination Date of the initial
            Term and ending on the 5th anniversary of the Termination Date (the
            "RENEWAL TERM"), if:

            1.    Landlord receives notice of exercise ("INITIAL RENEWAL
                  NOTICE") not less than 9 full calendar months prior to the
                  expiration of the initial Term and not more than 15 full
                  calendar months prior to the expiration of the initial Term;
                  and

            2.    Tenant is not in Default under the Lease at the time that
                  Tenant delivers its Initial Renewal Notice or at the time
                  Tenant delivers its Binding Notice (as defined below); and

            3.    Not more than 50% of the Premises is sublet (other than
                  pursuant to a Permitted Transfer, as defined in Section 11.04
                  of the Lease) at the time that Tenant delivers its Initial
                  Renewal Notice or at the time Tenant delivers its Binding
                  Notice; and

            4.    The Lease has not been assigned (other than pursuant to a
                  Permitted Transfer, as defined in Section 11.04 of the Lease)
                  prior to the date that Tenant delivers its Initial Renewal
                  Notice or prior to the date Tenant delivers its Binding
                  Notice.

      B.    Terms Applicable to Premises During Renewal Term.

            1.    The initial Base Rent rate per rentable square foot for the
                  Premises during the Renewal Term shall equal the Prevailing
                  Market (hereinafter defined) rate per rentable square foot for
                  the Premises. Base Rent during the Renewal Term shall
                  increase, if at all, in accordance with the increases assumed
                  in the determination of Prevailing Market rate. Base Rent
                  attributable to the Premises shall be payable in monthly
                  installments in accordance with the terms and conditions of
                  Section 4 of the Lease.

            2.    Tenant shall pay Additional Rent (i.e. Taxes and Expenses) for
                  the Premises during the Renewal Term in accordance with
                  Section 4 of the

                                       3
<PAGE>

                  Lease, and the manner and method in which Tenant reimburses
                  Landlord for Tenant's share of Taxes and Expenses and the Base
                  Year, if any, applicable to such matter, shall be some of the
                  factors considered in determining the Prevailing Market rate
                  for the Renewal Term.

      C.    Procedure for Determining Prevailing Market. Within 30 days after
            receipt of Tenant's Initial Renewal Notice, Landlord shall advise
            Tenant of the applicable Base Rent rate for the Premises for the
            Renewal Term. Tenant, within 15 days after the date on which
            Landlord advises Tenant of the applicable Base Rent rate for the
            Renewal Term, shall either (i) give Landlord final binding written
            notice ("BINDING NOTICE") of Tenant's exercise of its Renewal
            Option, or (ii) if Tenant disagrees with Landlord's determination,
            provide Landlord with written notice of rejection (the "REJECTION
            NOTICE"). If Tenant fails to provide Landlord with either a Binding
            Notice or Rejection Notice within such 15 day period, Tenant's
            Renewal Option shall be null and void and of no further force and
            effect. If Tenant provides Landlord with a Binding Notice, Landlord
            and Tenant shall enter into the Renewal Amendment (as defined below)
            upon the terms and conditions set forth herein. If Tenant provides
            Landlord with a Rejection Notice, Landlord and Tenant shall work
            together in good faith to agree upon the Prevailing Market rate for
            the Premises during the Renewal Term. When Landlord and Tenant have
            agreed upon the Prevailing Market rate for the Premises, such
            agreement shall be reflected in a written agreement between Landlord
            and Tenant, whether in a letter or otherwise, and Landlord and
            Tenant shall enter into the Renewal Amendment in accordance with the
            terms and conditions hereof. Notwithstanding the foregoing, if
            Landlord and Tenant are unable to agree upon the Prevailing Market
            rate for the Premises within 30 days after the date Tenant provides
            Landlord with the Rejection Notice, Tenant's Renewal Option shall be
            deemed to be null and void and of no force and effect.

      D.    Renewal Amendment. If Tenant is entitled to and properly exercises
            its Renewal Option, Landlord shall prepare an amendment (the
            "RENEWAL AMENDMENT") to reflect changes in the Base Rent, Term,
            Termination Date and other appropriate terms. The Renewal Amendment
            shall be sent to Tenant within a reasonable time after Landlord's
            receipt of the Binding Notice or other written agreement by Landlord
            and Tenant regarding the Prevailing Market rate, and Tenant shall
            execute and return the Renewal Amendment to Landlord within 15 days
            after Tenant's receipt of same, but, upon final determination of the
            Prevailing Market rate applicable during the Renewal Term as
            described herein, an otherwise valid exercise of the Renewal Option
            shall be fully effective whether or not the Renewal Amendment is
            executed.

      E.    Definition of Prevailing Market. For purposes of this Renewal
            Option, "PREVAILING MARKET" shall mean the arms length fair market
            annual rental rate per rentable square foot under renewal leases and
            amendments entered into on or about the date on which the Prevailing
            Market is being determined hereunder for space comparable to the
            Premises in the Building and office buildings comparable to the
            Building in the Bellevue central business district. The
            determination of Prevailing Market shall take into account any
            material economic differences between the terms of this Lease and
            any comparison lease or amendment, such as rent abatements,
            construction costs and other concessions and the manner, if any, in
            which the landlord under any such lease is reimbursed for operating
            expenses and taxes. The determination of Prevailing Market shall
            also take into consideration any reasonably anticipated changes in
            the Prevailing Market rate from the time such Prevailing Market rate
            is being determined and the time such Prevailing Market rate will
            become effective under this Lease.

IV.   ROOF SPACE FOR DISH/ANTENNA.

      A.    At any time during the Term, Tenant may deliver to Landlord written
            notice (a "ROOF SPACE NOTICE"): (i) stating that Tenant wishes to
            lease space on the roof of the Building for the purpose of
            installing, operating and maintaining a 24 (or smaller) inch
            dish/antenna or other communication device approved by the Landlord
            (the "DISH/ANTENNA"), (ii) setting forth a general description of,
            and precise specifications for, the Dish/Antenna (collectively, the
            "PLANS AND SPECIFICATIONS"), and (iii) specifying the size of such
            space that Tenant desires to lease (which size shall be measured in
            terms of square footage and shall in any event be not greater than
            50 square feet). Within 10 Business Days after

                                       4
<PAGE>

            receiving the Roof Space Notice, Landlord shall provide Tenant with
            written notice (the "ADVICE"): (x) as to whether, as of the date of
            Landlord's receipt of the Roof Space Notice, there is available for
            lease (or there can be made available for lease without material
            cost to Landlord and solely through Landlord's delivery of 30 days'
            prior written notice to any party then leasing the same) space on
            the roof of the Building ("QUALIFIED ROOF SPACE") that (1) is, in
            Landlord's sole good faith discretion, suitable for the
            installation, operation and maintenance of the Dish/Antenna as
            described in the Plans and Specifications, and (2) has a size
            satisfying the requirements set forth in the Roof Space Notice; (y)
            if no Qualified Roof Space is available for lease (and no Qualified
            Roof Space can be made available for lease without material cost to
            Landlord and solely through Landlord's delivery of 30 days' prior
            written notice to any party then leasing such Qualified Roof Space),
            as to whether the Reserved Roof Space (defined in Section IV.B
            below) would have been a Qualified Roof Space if the size of the
            Reserved Roof Space had satisfied the size requirements of the Roof
            Space Notice (but the Reserved Roof Space had otherwise been
            unchanged); and (z) specifying the commencement date for any space
            on the roof that may be described in the Advice pursuant to either
            of the preceding clauses (x) and (y) (i.e., a Qualified Roof Space
            or the Reserved Roof Space) and may be leased by Tenant pursuant to
            this Section IV.A (which commencement date shall be not later than
            45 days after the date on which Landlord delivers the Advice). For
            purposes hereof, a space on the roof of the Building shall not be
            deemed to be "available for lease" as of a particular date if, as of
            such date, either (i) any other party has a right to lease, occupy
            or use such space during all or any portion of the balance of the
            Term, or (ii) a then-existing tenant that is leasing such space has
            expressed to Landlord, in writing, its bona fide interest in
            extending or renewing its lease for such space or in entering into a
            new lease for such space and Landlord is then engaged in good faith
            negotiations with such existing tenant regarding such possible
            extension or renewal. If, as of the date on which Landlord receives
            the Roof Space Notice, Qualified Roof Space is available for lease
            (or can be made available for lease without material cost to
            Landlord and solely through Landlord's delivery of 30 days' prior
            written notice to any party then leasing such Qualified Roof Space),
            Tenant shall lease such Qualified Roof Space (or, if more than one
            Qualified Roof Space is available for lease or can so be made
            available for lease, then Tenant shall lease that Qualified Roof
            Space which is selected by Landlord in its sole and absolute
            discretion, as stated in the Advice) on the terms set forth in
            Section IV.E below. If, as of the date on which Landlord receives
            the Roof Space Notice, Qualified Roof Space is not available for
            lease (and no Qualified Roof Space can be made available for lease
            without material cost to Landlord and solely through Landlord's
            delivery of 30 days' prior written notice to any party then leasing
            such Qualified Roof Space), then, at Tenant's option (which shall be
            exercised by written notice to Landlord delivered within 10 Business
            Days after Tenant's receipt of the Advice), either (i) Tenant shall
            have the right to lease the Reserved Roof Space on the terms set
            forth in Section IV.E below, but only if the Reserved Roof Space
            would have been a Qualified Roof Space if the size of the Reserved
            Roof Space had satisfied the size requirements of the Roof Space
            Notice (but the Reserved Roof Space had otherwise been unchanged),
            or (ii) commencing on the date on which Landlord receives the Roof
            Space Notice, Tenant shall have a right of first offer (the "RIGHT
            OF FIRST OFFER") with respect to the first Qualified Roof Space that
            becomes available for lease after such date. The Right of First
            Offer shall be a one-time right of first offer, and shall be
            exercised as follows: within 10 Business Days after Landlord has
            determined that a Qualified Roof Space has become available for
            lease, Landlord shall provide Tenant with written notice (the "ROFO
            NOTICE") that Landlord is prepared to lease such Qualified Roof
            Space to Tenant for the remainder of the Term. Upon receipt of a
            ROFO Notice, Tenant may exercise its Right of First Offer to lease
            the Qualified Roof Space described therein, on the terms set forth
            in Section IV.E below, by delivering written notice of exercise to
            Landlord (the "NOTICE OF EXERCISE") within 5 Business Days after the
            date of Tenant's receipt of the ROFO Notice.

      B.    Notwithstanding anything herein to the contrary, Landlord represents
            and warrants to Tenant that a space on the roof of the Building
            which has a size of not less than 25 square feet nor more than 50
            square feet and, in Landlord's reasonable judgment, is suitable for
            the installation, operation and maintenance of a dish/antenna or
            other communication device of a type typically installed by tenants
            of class "A" office buildings (the "RESERVED ROOF SPACE") will, as
            of the

                                       5
<PAGE>

            date on which Landlord receives the Roof Space Notice, either (i) be
            available for lease, or (ii) be capable of being made available for
            lease without material cost to Landlord and solely through
            Landlord's delivery of 30 days' prior written notice to any party
            then leasing such space; provided, however, that, not having
            received the Plans and Specifications as of the date hereof,
            Landlord does not represent or warrant that the Reserved Roof Space
            will be suitable for the installation, operation and maintenance of
            the Dish/Antenna as described in the Plans and Specifications. If
            the Reserved Roof Space is a Qualified Roof Space but is not
            available for lease as of the date on which Landlord receives the
            Roof Space Notice, then Landlord shall, within 5 Business Days after
            such date, deliver the written notice necessary to cause the
            Reserved Roof Space to be made available for lease (as contemplated
            by clause (ii) of the preceding sentence).

      C.    Notwithstanding anything in Section IV.A above to the contrary,
            Tenant shall have no right to lease any space on the roof of the
            Building, and Landlord shall not be required to provide Tenant with
            an Advice or a ROFO Notice, as applicable, if, as of the date on
            which Landlord would otherwise be required to provide such Advice or
            ROFO Notice:

            1.    a Default has occurred and is then continuing; or

            2.    25% or more of the rentable square footage of the Premises is
                  then sublet (other than pursuant to a Permitted Transfer); or

            3.    Tenant is not then occupying a material portion of the
                  Premises; or

            4.    such space on the roof of the Building is not intended for the
                  exclusive use of Tenant during the remaining portion of the
                  Term.

      D.    Termination of Right of First Offer; Subordination.

            (i)   Any right of Tenant to lease any space on the roof of the
                  Building pursuant to this Section IV shall terminate on the
                  earlier to occur of: (i) the date on which Landlord would have
                  been required to provide Tenant with an Advice or a ROFO
                  Notice if Tenant had not been in violation of one or more of
                  the conditions set forth in Section IV.C above; or (ii)
                  Tenant's failure to deliver any applicable Notice of Exercise
                  within the 5-Business-Day period provided in Section IV.A
                  above.

            (ii)  Notwithstanding anything herein to the contrary, Tenant's
                  right to lease any Qualified Roof Space (other than the
                  Reserved Roof Space) pursuant to this Section IV is subject
                  and subordinate to any rights of any tenant of the Building
                  existing on the date of Landlord's receipt of the Roof Space
                  Notice.

      E.    Terms for Roof Space.

            1.    The term of any leasing by Tenant of any space on the roof of
                  the Building pursuant to this Section IV shall commence upon
                  the commencement date stated in the Advice or the ROFO Notice,
                  as applicable; provided, however, that such commencement date
                  shall not be later than 45 days after the date on which
                  Landlord delivers such Advice or ROFO Notice.

            2.    Tenant shall pay to Landlord $300.00 per month (the
                  "DISH/ANTENNA PAYMENTS") for use of the space on the roof of
                  the Building leased by Tenant (the "ROOF SPACE"). Tenant's
                  rights to install, operate and maintain the Dish/Antenna shall
                  be subject to Section 9.03 of the Lease. The Dish/Antenna
                  Payments shall constitute Additional Rent under the terms of
                  the Lease and Tenant shall be required to make these payments
                  in the same manner and at the same time as other payments of
                  Additional Rent and in strict compliance with the terms of
                  Section 4 of the Lease. Landlord reserves the right, at
                  Landlord's sole cost and expense, to relocate the Roof Space,
                  together with Tenant's Dish/Antenna equipment and
                  appurtenances, as reasonably necessary during the Term.
                  Landlord's designation shall take into account Tenant's use of
                  the

                                       6
<PAGE>

                  Dish/Antenna and the operating efficiency and/or functionality
                  of same. Notwithstanding the foregoing, Tenant's right to
                  install the Dish/Antenna shall be subject to the approval
                  rights of Landlord and Landlord's architect and/or engineer
                  with respect to the plans and specifications of the
                  Dish/Antenna, the manner in which the Dish/Antenna is attached
                  to the roof of the Building and the manner in which any cables
                  are run to and from the Dish/Antenna. The Dish/Antenna must be
                  tagged with weatherproof labels showing manufacturer, model,
                  frequency range, and name of Tenant. In addition, the cable
                  between the Dish/Antenna and Tenant's suite must be tagged in
                  the telecom closet on each floor with a label showing Tenant's
                  name, phone number and suite number. In addition to the Plans
                  and Specifications, all other documents Landlord reasonably
                  requires (and requests in writing not later than the date of
                  Landlord's delivery of the applicable Advice or ROFO Notice)
                  to review the installation of the Dish/Antenna (collectively,
                  the "ADDITIONAL INFORMATION") shall be submitted to Landlord
                  for Landlord's written approval no later than 20 days before
                  Tenant commences to install the Dish/Antenna. Tenant shall be
                  solely responsible for obtaining all necessary governmental
                  and regulatory approvals and for the cost of installing,
                  operating, maintaining and removing the Dish/Antenna. Tenant
                  shall notify Landlord upon completion of the installation of
                  the Dish/Antenna. If Landlord determines that the Dish/Antenna
                  equipment does not comply with the approved Plans and
                  Specifications and Additional Information, that the Building
                  has been damaged during installation of the Dish/Antenna or
                  that the installation was defective, Landlord shall notify
                  Tenant of any noncompliance or detected problems and Tenant
                  shall promptly commence and diligently cure the defects. If
                  the Tenant fails to promptly commence and diligently cure the
                  defects, Landlord shall have the right, but not the
                  obligation, to cure the same and Tenant shall pay to Landlord
                  upon demand the cost, as reasonably incurred by Landlord, of
                  correcting any defects and repairing any damage to the
                  Building caused by such installation. If at any time Landlord,
                  in its sole discretion, deems it necessary, Tenant shall
                  provide and install, at Tenant's sole cost and expense,
                  appropriate aesthetic screening, reasonably satisfactory to
                  Landlord, for the Dish/Antenna (the "AESTHETIC SCREENING").

            3.    Landlord agrees that Tenant, during the term for the Roof
                  Space, shall have access to the roof of the Building and the
                  Roof Space for the purpose of installing, maintaining,
                  repairing and removing the Dish/Antenna, the appurtenances and
                  the Aesthetic Screening, if any, all of which shall be
                  performed by Tenant or Tenant's authorized representative or
                  contractors, which shall be reasonably approved by Landlord,
                  at Tenant's sole cost and risk. It is agreed, however, that
                  only authorized engineers, employees or properly authorized
                  contractors of Tenant, FCC (defined below) inspectors, or
                  persons under their direct supervision will be permitted to
                  have access to the roof of the Building and the Roof Space.
                  Tenant further agrees to exercise firm control over the people
                  requiring access to the roof of the Building and the Roof
                  Space in order to keep to a minimum the number of people
                  having access to the roof of the Building and the Roof Space
                  and the frequency of their visits.

            4.    It is further understood and agreed that the installation,
                  maintenance, operation and removal of the Dish/Antenna, the
                  appurtenances and the Aesthetic Screening, if any, is not
                  permitted to damage the Building or the roof thereof, or
                  interfere with the use of the Building and roof by Landlord.
                  Tenant agrees to be responsible for any damage caused to the
                  roof or any other part of the Building, which may be caused by
                  Tenant or any of its agents or representatives.

            5.    If, in the sole judgment of Landlord, any electrical,
                  electromagnetic, radio frequency or other interference shall
                  result from the operation of any of the Dish/Antenna, Tenant
                  agrees that Landlord may, at Landlord's option, shut down
                  Tenant's equipment upon 8 hours prior notice to Tenant;
                  provided, however, if an emergency situation exists, which
                  Landlord reasonably determines in its sole discretion to be
                  attributable to the

                                       7
<PAGE>

                  Dish/Antenna, Landlord shall immediately notify Tenant orally,
                  who shall act immediately to remedy the emergency situation.
                  Should Tenant fail to so remedy said emergency situation,
                  Landlord may then act to shut down Tenant's equipment. Tenant
                  shall indemnify Landlord and hold it harmless from, and Tenant
                  waives, all expenses, costs, damages, losses, claims or other
                  liabilities arising out of said shutdown. Tenant agrees to
                  cease operations (except for intermittent testing on a
                  schedule approved by Landlord) until the interference has been
                  corrected to the satisfaction of Landlord. If such
                  interference has not been corrected within 30 days, Landlord
                  may require that Tenant immediately remove from the Roof Space
                  the specific item of equipment causing such interference, in
                  which latter case the Dish/Antenna Payments shall be reduced
                  by the portion of the fee applicable to such Dish/Antenna
                  equipment for the remainder of the Term and all other terms
                  and conditions of this Amendment shall remain in full force
                  and effect.

            6.    Tenant shall, at its sole cost and expense, and at its sole
                  risk, install, operate and maintain the Dish/Antenna in a good
                  and workmanlike manner, and in compliance with all Building,
                  electric, communication, and safety codes, ordinances,
                  standards, regulations and requirements, now in effect or
                  hereafter promulgated, of the Federal Government, including,
                  without limitation, the Federal Communications Commission (the
                  "FCC"), the Federal Aviation Administration ("FAA") or any
                  successor agency of either the FCC or FAA having jurisdiction
                  over radio or telecommunications, and of the state, city and
                  county in which the Building is located. Under this Lease, the
                  Landlord and its agents assume no responsibility for the
                  licensing, operation and/or maintenance of Tenant's equipment.
                  Tenant has the responsibility of carrying out the terms of its
                  FCC license in all respects. The Dish/Antenna shall be
                  connected to Landlord's power supply in strict compliance with
                  all applicable Building, electrical, fire and safety codes.
                  Neither Landlord nor its agents shall be liable to Tenant for
                  any stoppages or shortages of electrical power furnished to
                  the Dish/Antenna or the Roof Space because of any act,
                  omission or requirement of the public utility serving the
                  Building, or the act or omission of any other tenant, invitee
                  or licensee or their respective agents, employees or
                  contractors, or for any other cause beyond the reasonable
                  control of Landlord, and Tenant shall not be entitled to any
                  rental abatement for any such stoppage or shortage of
                  electrical power. Neither Landlord nor its agents shall have
                  any responsibility or liability for the conduct or safety of
                  any of Tenant's representatives, repair, maintenance and
                  engineering personnel while in or on any part of the Building
                  or the Roof Space.

            7.    The Dish/Antenna, the appurtenances and the Aesthetic
                  Screening, if any, shall remain the personal property of
                  Tenant, and shall be removed by Tenant at its own expense at
                  the expiration or earlier termination of this Lease or
                  Tenant's right to possession hereunder. Tenant shall repair
                  any damage caused by such removal, including the patching of
                  any holes to match, as closely as possible, the color
                  surrounding the area where the equipment and appurtenances
                  were attached. Tenant agrees to maintain all of the Tenant's
                  equipment placed on or about the roof or in any other part of
                  the Building in proper operating condition and maintain same
                  in satisfactory condition as to appearance and safety in
                  Landlord's sole discretion. Such maintenance and operation
                  shall be performed in a manner to avoid any interference with
                  any other tenants or Landlord. Tenant agrees that at all times
                  during the Term, it will keep the roof of the Building and the
                  Roof Space free of all trash or waste materials produced by
                  Tenant or Tenant's agents, employees or contractors.

            8.    In light of the specialized nature of the Dish/Antenna, Tenant
                  shall be permitted to utilize the services of its choice for
                  installation, operation, removal and repair of the
                  Dish/Antenna, the appurtenances and the Aesthetic Screening,
                  if any, subject to the reasonable approval of Landlord.
                  Notwithstanding the foregoing, Tenant must provide Landlord
                  with prior written notice of any such installation, removal or
                  repair and coordinate such work with Landlord in order to
                  avoid voiding or otherwise adversely affecting any warranties
                  granted to Landlord with respect to the

                                       8
<PAGE>

                  roof. If necessary, Tenant, at its sole cost and expense,
                  shall retain any contractor having a then existing warranty in
                  effect on the roof to perform such work (to the extent that it
                  involves the roof), or, at Tenant's option, to perform such
                  work in conjunction with Tenant's contractor. In the event the
                  Landlord contemplates roof repairs that could affect Tenant's
                  Dish/Antenna, or which may result in an interruption of the
                  Tenant's telecommunication service, Landlord shall formally
                  notify Tenant at least 30 days in advance (except in cases of
                  an emergency) prior to the commencement of such contemplated
                  work in order to allow Tenant to make other arrangements for
                  such service.

            9.    Tenant shall not allow any provider of telecommunication,
                  video, data or related services ("COMMUNICATION SERVICES") to
                  locate any equipment on the roof of the Building or in the
                  Roof Space for any purpose whatsoever, nor may Tenant use the
                  Roof Space and/or Dish/Antenna to provide Communication
                  Services to an unaffiliated tenant, occupant or licensee of
                  another building, or to facilitate the provision of
                  Communication Services on behalf of another Communication
                  Services provider to an unaffiliated tenant, occupant or
                  licensee of the Building or any other building.

            10.   Tenant acknowledges that Landlord may at some time establish a
                  standard license agreement (the "LICENSE AGREEMENT") with
                  respect to the use of Roof Space by tenants of the Building.
                  Tenant, upon request of Landlord, shall enter into such
                  License Agreement with Landlord provided that such agreement
                  does not materially alter the rights or obligations of Tenant
                  hereunder with respect to the Roof Space.

            11.   Tenant specifically acknowledges and agrees that the terms and
                  conditions of Section 13 of the Lease (Indemnity and Waiver of
                  Claims) shall apply with full force and effect to the Roof
                  Space and any other portions of the roof accessed or utilized
                  by Tenant, its representatives, agents, employees or
                  contractors.

            12.   If Tenant is in Default under any of the terms and conditions
                  of this Section IV or the Lease (as described in Section 18 of
                  the Lease), Landlord shall be permitted to exercise all
                  remedies provided under the terms of the Lease, including
                  removing the Dish/Antenna, the appurtenances and the Aesthetic
                  Screening, if any, and restoring the Building and the Roof
                  Space to the condition that existed prior to the installation
                  of the Dish/Antenna, the appurtenances and the Aesthetic
                  Screening, if any. If Landlord removes the Dish/Antenna, the
                  appurtenances and the Aesthetic Screening, if any, as a result
                  of a Default, Tenant shall be liable for all costs and
                  expenses Landlord incurs in removing the Dish/Antenna, the
                  appurtenances and the Aesthetic Screening, if any, and
                  repairing any damage to the Building, the roof of the Building
                  and the Roof Space caused by the installation, operation or
                  maintenance of the Dish/Antenna, the appurtenances, and the
                  Aesthetic Screening, if any.

                THE REMAINDER OF THIS PAGE IS INTENTIONALLY BLANK

                                       9
<PAGE>

                                    EXHIBIT G

                            JANITORIAL SPECIFICATIONS

                       [INSERT JANITORIAL SPECIFICATIONS]

                                       1<PAGE>

                      TERMS AND CONDITIONS OF STOCK OPTIONS

                                GRANTED UNDER THE

                   LIGHTBRIDGE, INC. 2004 STOCK INCENTIVE PLAN

      These terms and conditions shall apply to all Options granted by
Lightbridge, Inc., a Delaware corporation (hereinafter together with its
subsidiaries, where the context permits, referred to as the "Company"), under
its 2004 Stock Incentive Plan , as amended from time to time (the "Plan"),
unless otherwise specified in the written notice of option grant (the "Notice of
Grant") delivered by the Company to the grantee of an Option (a "Holder").
Capitalized terms used and not otherwise defined herein shall have the
respective meanings ascribed to such terms in the Plan.

      Section 1. GRANT OF OPTION. Each Option shall be evidenced by a Notice of
Grant, which may be in electronic form and may be electronically acknowledged
and accepted by the recipient, and shall give the Holder the right and option to
purchase from the Company shares of the Company's Common Stock, $.01 par value
per share (the "Common Stock"). The Notice of Grant shall set forth with respect
to the subject Option (i) its expiration date, (ii) its exercise price per
share, (iii) the maximum number of shares that the Holder may purchase upon
exercise thereof, and (iv) the vesting schedule. The Notice of Grant may also
contain other terms and conditions applicable to the Option, and in the event of
any conflict or inconsistency between these terms and conditions and the terms
contained in any Notice of Grant, the latter shall prevail. The right to
purchase shares under any Option shall be cumulative.

      Each Option is and shall be subject in every respect to the provisions of
the Plan, which is incorporated herein by reference and made a part hereof. In
the event of any conflict or inconsistency between the terms hereof or of any
Notice of Grant and those of the Plan, the terms of the Plan shall prevail.

      If an Option is granted to a person who is an employee of the Company or
an Affiliate, it shall be deemed to be an Incentive Stock Option to the extent
that it otherwise qualifies as such under applicable law. Any portion of such an
Option that does not so qualify, and any Option granted to any other Eligible
Person, shall be a Non-Statutory Stock Option.

      Section 2. EXERCISE OF OPTION. An Option shall be exercised by the
delivery of written notice to the Company (the "Notice") setting forth the
number of shares with respect to which the Option is to be exercised and the
address to which the certificates for such shares are to be mailed or otherwise
delivered, together with:

            (i) cash or check payable to the order of the Company for an amount
      equal to the option price for the number of shares specified in the
      Notice; or

            (ii) with the consent of the Committee, shares of Common Stock of
      the Company that (a) either have been purchased by the Holder on the open
      market, or have been beneficially owned by the Holder for a period of at
      least six (6) months and are not then

<PAGE>

      subject to restriction under any Company plan ("Mature Shares"), and (b)
      have a Fair Market Value on the date of surrender equal to the option
      price for the shares as to which the Option is being exercised; or

            (iii) if the Common Stock is registered under the Exchange Act at
      the time of exercise, by delivery to the Company of a properly executed
      Notice along with irrevocable instructions to a broker to deliver promptly
      to the Company cash or a check payable and acceptable to the Company in an
      amount equal the option price for the shares as to which the Option is
      being exercised; provided that in the event that the optionee chooses to
      pay the purchase price as so provided, the optionee and the broker shall
      comply with such procedures and enter into such agreements of indemnity
      and other agreements as the Committee shall prescribe as a condition of
      such payment procedure (including, in the case of an optionee who is an
      executive officer of the Company, such procedures and agreements as the
      Committee deems appropriate in order to avoid any extension of credit in
      the form of a personal loan to such officer); provided further that the
      Company need not act upon such exercise notice until the Company receives
      full payment of the exercise price; or

            (iv) with the consent of the Committee, by reducing the number of
      Option shares otherwise issuable to the Holder upon exercise of the Option
      by a number of shares of Common Stock having a Fair Market Value equal to
      the option price for the shares as to which the Option is being exercised;
      provided, however, that the Holder otherwise holds an equal number of
      Mature Shares; or

            (v) with the consent of the Committee, a combination of (i) through
      (iv).

      Section 3. CONDITIONS AND LIMITATIONS. The Company, in its discretion, may
file a registration statement on Form S-8 under the Securities Act of 1933 to
register shares of Common Stock reserved for issuance under the Plan. At any
time at which such a registration statement is not in effect, it shall be an
additional condition precedent to any exercise of an Option that the Holder
shall deliver to the Company a customary "investment letter" satisfactory to the
Company and its counsel in which, among other things, the Holder shall state
that the Holder is purchasing the shares for investment and acknowledges that
they are not freely transferable except in compliance with state and federal
securities laws.

      Section 4. DELIVERY OF SHARES. Within a reasonable time after receipt by
the Company of the Notice and payment for any shares to be purchased under an
Option and, if required as a condition to exercise, the investment letter
described in Section 3, the Company will deliver or cause to be delivered to the
Holder (or if any other individual or individuals are exercising the Option, to
such individual or individuals) at the address specified in the Notice a
certificate or certificates for the number of shares with respect to which the
Option is then being exercised, registered in the name or names of the
individual or individuals exercising the Option, either alone or jointly with
another person or persons with rights of survivorship, as the individual or
individuals exercising the Option shall prescribe in writing to the Company at
or prior to such purchase; provided, however, that if any law or regulation or
order of the SEC or other body having jurisdiction in the premises shall require
the Company or the Holder (or the individual or individuals exercising the
Option) to take any action in connection with the shares then being

                                      -2-
<PAGE>

purchased, the date for the delivery of the certificates for such shares shall
be extended for the period necessary to take and complete such action, it being
understood that the Company shall have no obligation to take and complete any
such action. The Company may imprint upon such certificate such legends
referencing stock transfer restrictions which counsel for the Company considers
appropriate. Delivery by the Company of the certificates for such shares shall
be deemed effected for all purposes when the Company or a stock transfer agent
of the Company shall have deposited such certificates in the United States mail,
addressed to the Holder, at the address specified in the Notice.

      Section 5. ADJUSTMENTS UPON CHANGES IN CAPITALIZATION. The existence of
any Option shall not affect in any way the right or power of the Company or its
stockholders to make or authorize any or all adjustments, recapitalizations,
reorganizations or other changes in the Company's capital structure or its
business, or any merger or consolidation of the Company, or any issuance of
Common Stock, or any issuance of bonds, debentures, preferred or prior
preference stock or other capital stock ahead of or affecting the Common Stock
or the rights thereof, or the dissolution or liquidation of the Company, or any
sale or transfer of all or any part of its assets or business, or any other
corporate act or proceeding, whether of a similar character or otherwise.

      If the Company shall effect a stock dividend, stock split or similar
change in capitalization affecting the shares of Common Stock outstanding, in
any such case without receiving compensation therefor in money, services or
property, then the number, class, and price per share of shares of Common Stock
subject to each Option shall be appropriately adjusted in such a manner as to
entitle the Holder to receive upon exercise of the Option, for the same
aggregate cash consideration, the same total number and class of shares as the
Holder would have received as a result of the event requiring the adjustment had
the Holder exercised the Option in full immediately prior to such event.

      Except as hereinbefore expressly provided, the issuance by the Company of
shares of stock of any class, or securities convertible into shares of stock of
any class, for cash or property, or for labor or services, either upon direct
sale or upon the exercise of rights or warrants to subscribe therefor, or upon
the conversion of shares or obligations of the Company convertible into such
shares or other securities, shall not affect, and no adjustment by reason
therefor shall be made with respect to, the number or price of shares of Common
Stock then subject to any Option.

      Section 6. EFFECT OF CERTAIN TRANSACTIONS. After a merger of one or more
corporations with or into the Company or after a consolidation of the Company
and one or more corporations in which the stockholders of the Company
immediately prior to such merger or consolidation own after such merger or
consolidation shares representing at least fifty percent (50%) of the voting
power of the Company or the surviving or resulting corporation, as the case may
be, a Holder shall, at no additional cost, be entitled upon exercise of an
Option to receive in lieu of the shares of Common Stock as to which the Option
was exercisable immediately prior to such event, the number and class of shares
of stock or other securities, cash or property (including, without limitation,
shares of stock or other securities of another corporation or Common Stock) to
which the Holder would have been entitled pursuant to the terms of the agreement
of merger or consolidation if, immediately prior to such merger or
consolidation, the Holder had been the

                                      -3-
<PAGE>

holder of record of a number of shares of Common Stock equal to the number of
shares for which the Option shall be so exercised.

      If a Change in Control occurs while an Option remains outstanding, then
fifty percent (50%) of any remaining unvested shares purchasable under such
Option after the effective date of a Change in Control will be deemed vested in
accordance with the terms hereof, and, subject to the provisions of clause (iii)
in the immediately following paragraph, the remaining fifty percent (50%) shall
continue to vest in accordance with the terms of such Option. The acceleration
required under this paragraph shall not be deemed to limit the authority of the
Committee to take the actions set forth in the immediately following paragraph.

      Upon the occurrence of a Change of Control while an Option remains
outstanding, then (i) subject to the provisions of clause (iii) below, after the
effective date of such Change of Control, the Holder of the Option shall be
entitled, upon exercise of the Option, to receive, in lieu of the shares of
Common Stock as to which the Option was exercisable immediately prior to the
Change of Control, the number and class of shares of stock or other securities,
cash or property (including, without limitation, shares of stock or other
securities of another corporation or Common Stock) to which the Holder would
have been entitled pursuant to the terms of the Change of Control if,
immediately prior to the Change of Control, the Holder had been the holder of a
number of shares of Common Stock equal to the number of shares as to which the
Option shall be so exercised; (ii) the Committee may accelerate, fully or in
part, the time for exercise of the Option so that, from and after a date prior
to the effective date of the Change of Control specified by the Committee, the
Option shall be exercisable to the extent determined by the Committee; or (iii)
the Option may be canceled by the Committee as of the effective date of the
Change of Control, provided that (x) prior written notice of such cancellation
shall be given to the Holder and (y) the Holder shall have the right to exercise
the Option for a period of up to ninety (90) days after the effective date of
the Change in Control to the extent that the same is then exercisable including
as provided in the immediately preceding paragraph or, if the Committee shall
have accelerated the time for exercise of the Option pursuant to clause (ii)
above, in full during the thirty (30) day period preceding the effective date of
the Change of Control.

      Section 7. RIGHTS OF HOLDER. No person shall, by virtue of the granting of
an Option, be deemed to be a holder of any shares purchasable under the Option
or to be entitled to the rights or privileges of a holder of such shares unless
and until the Option has been exercised with respect to such shares and they
have been issued pursuant to that exercise of the Option.

      The Company shall, at all times while any portion of any Option is
outstanding, reserve and keep available, out of shares of its authorized and
unissued stock or reacquired shares, a sufficient number of shares of its Common
Stock to satisfy the requirements of the Option; shall comply with the terms of
the Option promptly upon exercise of the option rights; and shall pay all fees
or expenses necessarily incurred by the Company in connection with the issuance
and delivery of shares pursuant to the exercise of the Option.

      Section 8. TRANSFER AND TERMINATION. No Option is transferable by the
Holder otherwise than by will or under the laws of descent and distribution. The
granting of an Option shall not impose upon the Company any obligation to retain
or to continue to retain the services

                                      -4-
<PAGE>

of the Holder in any capacity. The right of the Company to terminate the
services of the Holder shall not be diminished or affected by reason of the fact
that an Option has been granted to such Holder.

      An Option shall terminate in all respects, and all rights and options to
purchase shares thereunder shall terminate, upon the expiration date set forth
in the Notice of Grant. Each Option is exercisable, during the Holder's
lifetime, only by the Holder, and by the Holder only while the Holder is serving
as an Eligible Person, except as follows:

            (i) If the Holder ceases to serve as an Eligible Person by reason of
      death before the expiration date of the Option, the Option may thereafter
      be exercised, to the extent exercisable at the date of death, by the legal
      representative or legatee of the Holder for a period of one (1) year after
      the date of death, or until the expiration of the stated term of the
      Option, if earlier.

            (ii) If the Holder ceases to serve as an Eligible Person by reason
      of Disability before the expiration date of the Option, the Holder shall
      have the right to exercise the Option, to the extent exercisable at the
      date of such cessation of service, for a period of one (1) year after the
      date of such cessation of service, or until the expiration of the stated
      term of the Option, if earlier.

            (iii) If the Holder ceases to serve as an Eligible Person by reason
      of Normal Retirement before the expiration date of the Option, the Holder
      shall have the right to exercise the Option, to the extent exercisable at
      the date of such cessation of service, for a period of ninety (90) days
      after the date of such cessation of service, or until the expiration of
      the stated term of the Option, if earlier.

            (iv) If the Holder ceases to serve as an Eligible Person for any
      reason other than death, Disability, or Normal Retirement before the
      expiration date of the Option, the Holder shall have the right to exercise
      the Option, to the extent exercisable at the date of such cessation of
      service, for a period of ninety (90) days after the date of such cessation
      of service, or until the expiration of the stated term of the Option, if
      earlier.

      Section 9. NOTIFICATION OF DISQUALIFYING DISPOSITION. If an Option
qualifies as an Incentive Stock Option, in whole or in part, the Holder shall
notify the Company in writing immediately after making a Disqualifying
Disposition, as defined below, of any shares of Common Stock received pursuant
to the exercise of the Option. The Holder shall also provide the Company with
any information that the Company shall request concerning any such Disqualifying
Disposition.

            9.1 DISQUALIFYING DISPOSITION. A "Disqualifying Disposition" shall
have the meaning specified in Section 421(b) of the Code or any successor
provision; as of the date of adoption of these terms and conditions, a
Disqualifying Disposition is any disposition (including any sale) of shares
acquired upon exercise of an Incentive Stock Option before the later of (a) the
second anniversary of the date of grant of the Option or (b) the first
anniversary of the date on which the Holder acquired the shares by exercising
the Option, provided that such holding period requirements terminate upon the
death of the Holder.

                                      -5-
<PAGE>

            9.2 FORFEITURE OF FAVORABLE TAX TREATMENT. If an Option qualifies as
an Incentive Stock Option, the Holder acknowledges that the Holder will forfeit
the favorable income tax treatment otherwise available with respect to the
exercise of the Option if the Holder makes a Disqualifying Disposition of shares
received upon exercise of the Option.

      Section 10. WITHHOLDING OF TAXES.

            10.1 UPON A DISQUALIFYING DISPOSITION. If the Company in its
discretion determines that it is obligated to withhold tax with respect to a
Disqualifying Disposition of shares of Common Stock received on exercise of an
Option, the Holder agrees that the Company may withhold from the Holder's wages,
or other amounts due to the Holder from the Company, the appropriate amount of
federal, state or local withholding taxes attributable to such Disqualifying
Disposition.

            10.2 UPON TREATMENT AS A NON-STATUTORY OPTION. If any portion of an
Option is treated as a Non-Statutory Stock Option, the Holder hereby agrees that
the Company may withhold from the Holder's wages, or other amounts due to the
Holder from the Company, the appropriate amount of federal, state and local
withholding taxes attributable to the Holder's exercise of such Non-Statutory
Option.

            10.3 ELECTION AS TO METHOD OF SATISFYING WITHHOLDING OBLIGATION. At
the Holder's election, the amount required to be withheld may be satisfied, in
whole or in part, by (a) authorizing the Company to withhold from shares of
Common Stock to be issued pursuant to the exercise of a Non-Statutory Option a
number of shares with an aggregate Fair Market Value that would satisfy the
minimum withholding amount due with respect to such exercise, or (b)
transferring to the Company Mature Shares with an aggregate Fair Market Value
that would satisfy the minimum withholding amount due.

            10.4 AGREEMENT TO REIMBURSE COMPANY FOR WITHHOLDING OBLIGATION. The
Holder further agrees that, if the Company does not withhold an amount from the
Holder's wages sufficient to satisfy the Company's withholding obligation, the
Holder will reimburse the Company on demand, in cash, for the amount
underwithheld.

      Section 11. NOTICE. Any notice to be given to the Company under these
terms and conditions shall be deemed sufficient if addressed to the Company and
delivered by hand or by mail to the Treasurer of the Company, 30 Corporate
Drive, Burlington, Massachusetts 01803 or such other address as the Company may
hereafter designate.

      Any notice to be given to the Holder hereunder shall be deemed sufficient
if addressed to and delivered in person to the Holder or when deposited in the
mail, postage prepaid, addressed to the Holder at the Holder's address furnished
to the Company.

      Section 12. GOVERNMENT AND OTHER REGULATIONS. Each Option is subject to
all laws, regulations and orders of any governmental authority which may be
applicable thereto and, notwithstanding any of the provisions hereof, the Holder
agrees that the Holder will not exercise an Option nor will the Company be
obligated to issue or sell any shares of stock thereunder if the exercise
thereof or the issuance or sale of such shares, as the case may be, would
constitute a violation by the Holder or the Company of any such law, regulation
or order or any provision

                                      -6-
<PAGE>

thereof. The Company shall not be obligated to take any affirmative action in
order to cause the exercise of an Option or the issuance or sale of shares
pursuant thereto to comply with any such law, regulation, order or provision.

      Section 13. LOCK-UP AGREEMENT. The Holder agrees that upon request of the
Company or the underwriters managing any underwritten offering of the Company's
securities, the Holder shall agree in writing that for a period of time not to
exceed one hundred eighty (180) days from the effective date of any registration
of securities of the Company the Holder will not sell, make any short sale of,
loan, grant any option for the purchase of, or otherwise dispose of any shares
of Common Stock issued pursuant to the exercise of any Option without the prior
written consent of the Company or such underwriters, as the case may be.

      Section 14. GOVERNING LAW. These terms and conditions and all Options
shall be governed by, and construed and enforced in accordance with, the
substantive laws of The Commonwealth of Massachusetts, without regard for
principles of conflicts of laws.

                                      -7-

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