<PAGE>
                                                                    Exhibit 10.7


                                    SUBLEASE


SUBLANDLORD:               ROWECOM INC., a Delaware corporation

SUBTENANT:                 CELARIX, INC., a Delaware corporation

PREMISES:                  19,872 rentable square feet of the building located
                           at 60 Aberdeen Avenue, Cambridge, Middlesex County,
                           Massachusetts (the "Building")

<PAGE>

                                TABLE OF CONTENTS

<TABLE>

<S>                                                                                                  <C>
ARTICLE I............................................................................................1
REFERENCE DATA.......................................................................................1
         1.1  SUBJECTS REFERRED TO...................................................................1
ARTICLE II...........................................................................................2
PREMISES AND APPURTENANT RIGHTS......................................................................2
         2.1  SUBLEASE OF PREMISES...................................................................2
         2.2  APPURTENANT RIGHTS AND RESERVATIONS....................................................2
         2.3  PARKING................................................................................3
         2.4  RIGHT OF FIRST OFFER...................................................................3
ARTICLE III..........................................................................................3
TERM OF THE SUBLEASE.................................................................................3
         3.1  COMMENCEMENT AND EXPIRATION OF TERM....................................................4
ARTICLE IV...........................................................................................4
FIXED RENT...........................................................................................4
         4.1  FIXED RENT.............................................................................4
         4.2  RENT CREDIT............................................................................4
ARTICLE V............................................................................................4
TAX CHARGES..........................................................................................4
         5.1   DEFINITIONS...........................................................................4
         5.2  ADDITIONAL RENT........................................................................5
         5.3  REFUND OF TAXES........................................................................5
         5.4  SURVIVAL OF PAYMENTS...................................................................5
ARTICLE VI...........................................................................................5
SECTION INTENTIONALLY DELETED........................................................................5
ARTICLE VII..........................................................................................5
USE OF PREMISES......................................................................................5
         7.1  PERMITTED USES.........................................................................5
         7.2  INSTALLATIONS AND ALTERATIONS BY SUBTENANT.............................................6
ARTICLE VIII.........................................................................................7
ASSIGNMENT AND SUBLETTING............................................................................7
         8.1  PROHIBITION............................................................................7
         8.2  OTHER REQUIREMENTS AND PROVISIONS......................................................8
ARTICLE IX...........................................................................................9
RESPONSIBILITY FOR REPAIRS AND CONDITION OF PREMISES.................................................9
         9.1  SUBLANDLORD REPAIRS AND MAINTENANCE....................................................9
         9.2  SUBTENANT'S AGREEMENT..................................................................9
         9.3  HEAVY MACHINERY........................................................................9
         9.4  ELECTRICITY............................................................................9
         9.5  OTHER UTILITIES........................................................................10
         9.6  INTERRUPTION OR CURTAILMENT OF SERVICES................................................10
ARTICLE X............................................................................................10
INDEMNITY AND INSURANCE..............................................................................10
         10.1  SUBTENANT'S INDEMNITY.................................................................10
         10.2  INSURANCE.............................................................................11
         10.3  SUBTENANT'S RISK......................................................................11
         10.4  INJURY CAUSED BY THIRD PARTIES........................................................11
ARTICLE XI...........................................................................................12
SUBLANDLORD'S ACCESS TO PREMISES.....................................................................12
         11.1  SUBLANDLORD'S RIGHTS..................................................................12
ARTICLE XII..........................................................................................12
DAMAGE OR DESTRUCTION................................................................................12
         12.1  DAMAGE OR DESTRUCTION.................................................................12
ARTICLE XIII.........................................................................................12
CONDEMNATION.........................................................................................12


                                       i
<PAGE>

                                      -ii-


         13.1  CONDEMNATION..........................................................................12
ARTICLE XIV..........................................................................................13
DEFAULT..............................................................................................13
         14.1  SUBTENANT'S DEFAULT...................................................................13
ARTICLE XV...........................................................................................15
MISCELLANEOUS PROVISIONS.............................................................................15
         15.1  EXTRA HAZARDOUS USE...................................................................16
         15.2  WAIVER................................................................................16
         15.3  COVENANT OF QUIET ENJOYMENT...........................................................16
         15.4  FORCE MAJEURE, ETC....................................................................17
         15.5  ASSIGNMENT OF RENTS AND TRANSFER OF TITLE.............................................17
         15.6  RULES AND REGULATIONS.................................................................17
         15.7  ADDITIONAL CHARGES....................................................................17
         15.8  INVALIDITY OF PARTICULAR PROVISIONS...................................................17
         15.9  PROVISIONS BINDING....................................................................18
         15.10  NOTICES..............................................................................18
         15.11  WHEN SUBLEASE BECOMES BINDING........................................................18
         15.12  PARAGRAPH HEADINGS...................................................................18
         15.13  RIGHTS OF MORTGAGEE AND GROUND LESSOR................................................18
         15.14  ESTOPPEL CERTIFICATES................................................................19
         15.15  REMEDYING DEFAULTS...................................................................20
         15.16  HOLDING OVER.........................................................................20
         15.17  SURRENDER OF PREMISES................................................................20
ARTICLE XVI..........................................................................................21
BROKERAGE............................................................................................21
         16.1  BROKERAGE.............................................................................21
ARTICLE XVII.........................................................................................21
EXCULPATORY CLAUSE...................................................................................21
         17.1  INTENTIONALLY DELETED.................................................................21
         17.2  ACTIONS AGAINST SUBLANDLORD...........................................................21
         17.3  PERFORMANCE BY LANDLORD; PERFORMANCE BY SUBLANDLORD UNDER MASTER LEASE................21
                  17.3.1  LANDLORD PERFORMANCE OF CERTAIN OBLIGATIONS................................21
                  17.3.2  NO LIABILITY FOR LANDLORD PERFORMANCE......................................21
                  17.3.3  ENFORCEMENT OF LANDLORD OBLIGATIONS........................................22
                  17.3.4  NO MASTER LEASE DEFAULT....................................................22
                  17.3.5  CONSENT OF LANDLORD........................................................22
ARTICLE XVIII........................................................................................22
SUBMISSION TO JURISDICTION, ETC......................................................................22
         18.1  GOVERNING LAW.........................................................................22
         18.2  RECOVERY OF FEES......................................................................22
ARTICLE XIX..........................................................................................23
SECURITY DEPOSIT.....................................................................................23
         19.1  PAYMENT OF SECURITY DEPOSIT...........................................................23
         19.2  NO ENCUMBRANCES.......................................................................24
         19.3  TRANSFER OF SECURITY DEPOSIT..........................................................24
</TABLE>

<PAGE>

                                    SUBLEASE

         This Sublease is entered into as of this 8th day of December, 1999, by
and between ROWECOM INC., a Delaware corporation (hereinafter referred to as
"Sublandlord") and CELARIX, INC. a Delaware corporation (hereinafter referred to
as "Subtenant").

         WHEREAS, WESTERN PROPERTIES MASTER LLC, a Delaware limited liability
company ("Landlord") is the owner and lessor of the Property, as defined in
Paragraph 1.1 hereof;

         WHEREAS, Landlord has entered into a Master Lease with Sublandlord for
the Property (attached hereto as Schedule "1," the "Master Lease");

         WHEREAS, Subtenant desires to sublease a portion of the Property from
Sublandlord and Sublandlord desires to sublease such premises to Subtenant;

         NOW, THEREFORE, in consideration of the mutual promises, covenants and
conditions hereinafter contained, and for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Sublandlord and
Subtenant agree as follows:

                                    ARTICLE I

                                 REFERENCE DATA

         1.1  SUBJECTS REFERRED TO.

         Each reference in this Sublease to any of the following subjects shall
be construed to incorporate the data stated for that subject in this Section
1.1:

SUBLANDLORD'S ADDRESS:              Rowecom Inc.
                                    15 Southwest Park
                                    Westwood, Massachusetts 02090

SUBTENANT'S
ORIGINAL ADDRESS:                   Celarix, Inc.
                                    Suite 400
                                    254 Friend Street
                                    Boston, Massachusetts  02114

PREMISES:                           The first floor of the building located at
                                    60 Aberdeen Avenue, Cambridge, Middlesex
                                    County, Massachusetts (the "Building")
                                    containing approximately 19,872 rentable
                                    square feet and substantially as shown
                                    outlined on EXHIBIT A

<PAGE>

PROPERTY:                           The land with the Building thereon, with an
                                    address at 60 Aberdeen Avenue, Cambridge,
                                    Middlesex County, Massachusetts

FIXED RENT:
                                    PERIOD            MONTHLY RENT   RENTAL RATE

                                    1/1/00 - 5/31/06  $49,680        $30/sq. ft.

SUBTENANT'S
PROPORTIONATE
BUILDING SHARE:                     50%

OCCUPANCY DATE:                     December 15, 1999

RENT COMMENCEMENT
DATE:                               January 1, 2000

ACCESS:                             Subtenant shall have 24 hours per day, 7
                                    days per week, 52 weeks per year, access to
                                    the premises.

PERMITTED USE:                      Any and all uses permitted under the Master
                                    Lease

SECURITY DEPOSIT:                   $250,000

PUBLIC LIABILITY
INSURANCE LIMITS:                   $2,000,000 per occurrence for bodily injury
                                    (including death) and $1,000,000 per
                                    occurrence for property damage.

TERM:                               See Section 3.1

                                   ARTICLE II

                         PREMISES AND APPURTENANT RIGHTS

         2.1 SUBLEASE OF PREMISES. Sublandlord hereby demises and subleases to
Subtenant, and Subtenant hereby accepts from Sublandlord, the Premises, for the
Term of this Sublease and upon and subject to the terms and conditions
hereinafter set forth.

         2.2  APPURTENANT RIGHTS AND RESERVATIONS.

         (A) Subtenant shall have, as appurtenant to the Premises, the
non-exclusive right to use, and permit its invitees to use in common with
others, common driveways, parking areas and walkways necessary for access to the
Building; but such rights shall always be subject to reasonable rules and
regulations from time to time established by Sublandlord and Landlord and to the
right of Sublandlord and

<PAGE>

Landlord to designate and change from time to time areas and facilities to be
used, provided such designation or change does not materially interfere with use
and occupancy of the Premises or Subtenant's means of access thereto.

         (B) Excepted and excluded from the Premises are the ceiling, floor,
perimeter walls and exterior windows, except the inner surfaces of each thereof,
but the entry doors to the Premises are a part thereof; and Subtenant agrees
that Sublandlord shall have the right, prior to the Commencement Date, to place
utility lines, pipes and the like in, over and upon the Premises and to make
such other modifications to the systems servicing the Building and the Premises
as Sublandlord deems desirable from time to time, provided that such
modifications do not deprive Subtenant of any square footage, impact the service
to the Premises by Building Systems or materially adversely impact Subtenant's
use and enjoyment of the Premises. In exercising such right, Sublandlord shall
use commercially reasonable efforts to minimize disruption of Subtenant's use of
the Premises.

         2.3 PARKING. Subtenant shall have the right to use without cost and on
a non-exclusive, unreserved basis up to three (3) unreserved parking spaces per
every one thousand (1,000) rentable square feet occupied at any given time by
Subtenant. Subtenant's use of the parking spaces shall be subject to all
reasonable rules and regulations established by Sublandlord and/or Landlord from
time to time.

         2.4 RIGHT OF FIRST OFFER. Prior to subleasing any portion of the Leased
Premises (as defined in the Master Lease) to any third party, Sublandlord shall
offer such space to Subtenant in writing, specifying the term, rent,
availability of Subtenant improvement allowances and other material terms (the
"Offered Terms"). Subtenant shall have ten (10) days after receipt of the
Offered Terms in writing within which to accept or reject Sublandlord's offer
(failure to act within such 10-day period shall be deemed to be a rejection of
the offer). If Subtenant accepts the offer, Sublandlord and Subtenant shall
enter into an amendment to this Sublease memorializing the Offered Terms and
adding the applicable space within fifteen days after the date of acceptance. If
Subtenant rejects or is deemed to have rejected Sublandlord's offer, Sublandlord
shall be free to sublease the offered space on terms substantially similar to
the Offered Terms or at such a rental rate per square foot which shall be
greater than the rental rate per square foot included in the Offered Terms
(without any future obligation by Sublandlord to offer such offered space to
Subtenant); PROVIDED, that if Sublandlord shall offer the offered space to a
prospective sublessee at such a rental rate per square foot which shall be less
than the rental rate per square foot included in the Offered Terms (the "Reduced
Offered Terms"), Sublandlord shall be obligated to offer the offered space to
Subtenant at the Reduced Offered Terms. Subtenant shall have two (2) business
days after receipt of the Reduced Offered Terms in writing within which to
accept or reject Sublandlord's offer (failure to act within such two (2)
business day period shall be deemed to be a rejection of the offer), after which
Sublandlord shall have no future obligation to offer such offered space to
Subtenant.

                                   ARTICLE III

                              TERM OF THE SUBLEASE

<PAGE>

         3.1 COMMENCEMENT AND EXPIRATION OF TERM. The term of this Sublease
(herein referred to as the "Term") shall commence on the Commencement Date, as
defined in Section 1.1 and shall terminate on May 31, 2006, unless sooner
terminated as herein provided (the "Expiration Date").

                                   ARTICLE IV

                                   FIXED RENT

         4.1 FIXED RENT. Subtenant agrees to pay to Sublandlord, or as directed
by Sublandlord, without offset, abatement, deduction or demand, the Fixed Rent.
The Fixed Rent shall be payable in lawful money of the United States, in equal
monthly installments, in advance, on the first day of each and every calendar
month during the Term of this Sublease commencing on the Rent Commencement Date,
at Sublandlord's Address, or at such other place as Sublandlord shall from time
to time designate by notice. Notwithstanding the foregoing, simultaneously with
the execution of this Sublease, Subtenant is paying Sublandlord the monthly
installment for the first month of the Term (January, 2000). The Fixed Rent
shall be as follows during the Term:

         (B) Fixed Rent for any partial month shall be prorated on a daily
basis.

         (C) If any installment of Fixed Rent, additional rent or any other sum
due hereunder is not paid when due more than one time during any lease year of
the Term or any Extension Term hereunder, administrative fee of 5% of such
overdue amount shall be immediately payable by Subtenant in connection with each
subsequent late payment within such Lease year.

         4.2 RENT CREDIT. Subject to the limitations of Section 17 of this
Sublease, the provisions of Section 3.2.1 of the Master Lease are incorporated
herein by reference, solely with respect to the first floor space (19,872 RSF)
as referenced on page 5 of the Master Lease.

                                    ARTICLE V

                                   TAX CHARGES

         5.1 DEFINITIONS. For purposes of this Article V, "Real Estate Taxes"
shall mean all or any of the real estate taxes and assessments imposed by any
governmental authority having jurisdiction upon the Property and Building, or
any tax or assessment hereafter imposed in whole or in part in substitution for
such real estate taxes and/or assessments (excluding water and sewerage
charges). The term "Tax Year" shall mean the fiscal year 2000 and each
subsequent fiscal year thereafter. "Real Estate Taxes" shall not include income
taxes, franchise, gift, transfer, excise, capital stock, estate, succession or
inheritance taxes or penalties or interest for the late payment of Real Estate
Taxes. As provided in Section 9.5 below, Subtenant shall purchase and receive
water and gas for the Premises directly from the public utility company serving
the Building. All costs for water and sewerage shall be paid by Subtenant, as
additional rent, within thirty (30) days of receipt of such bill from
Sublandlord or Landlord.

<PAGE>

         5.2 ADDITIONAL RENT. Subtenant shall pay to Sublandlord during the Term
of this Sublease, as additional rent, Subtenant's Proportionate Share of Real
Estate Taxes.

         5.3 REFUND OF TAXES. If Sublandlord receives any refund of Real Estate
Taxes for any Tax Year for which Subtenant has made a payment pursuant hereto,
Sublandlord shall (after deducting from such refund all reasonable expenses
incurred in connection therewith) pay Subtenant, if Subtenant is not in default
hereunder beyond applicable cure periods, Subtenant's Proportionate Share of the
net refund. Subtenant shall pay Sublandlord Subtenant's Proportionate Share of
the costs and reasonable expenses of any nature (including, without limitation,
reasonable consulting, appraisal and legal fees) incurred by Sublandlord in
connection with any tax protest or other proceeding or arrangement either
requested by Subtenant or leading to a reduction in Real Estate Taxes.

         5.4 SURVIVAL OF PAYMENTS. If any Tax Year is only partially within the
Term, all payments pursuant hereto shall be appropriately prorated, based on the
portion of the Tax Year which is within the Term. Subtenant's obligation to make
the payments required by this Article V shall survive the Expiration Date or any
sooner termination of this Sublease.

                                   ARTICLE VI

                          SECTION INTENTIONALLY DELETED

                                   ARTICLE VII

                                 USE OF PREMISES

         7.1  PERMITTED USES.

         (A) Subtenant agrees that the Premises shall be used and occupied by
Subtenant only for Permitted Uses and for no other purpose.

         (B) Notwithstanding the Permitted Uses, Subtenant shall not use or
permit all or any part of the Premises to be used for the: (1) storage (with the
intent to sell or distribute) or sale of any alcoholic beverage; (2) rendition
of any health or related services, conduct of a school or conduct of any
business which invites the general public to the Premises; or (3) conduct of any
public auction.

         (C) Subtenant agrees to conform to the following provisions during the
Term of this Sublease:

                  (1) Subtenant shall cause all freight to be delivered to or
         removed from the Building and the Premises in accordance with
         reasonable rules and regulations established by Sublandlord therefor.

                  (2) Subtenant will not place on the exterior of the Premises
         (including both interior and exterior surfaces of doors and interior
         surfaces of windows) or on any part of the Building outside the
         Premises, any sign, symbol, advertisement or the like which is visible
         to public view outside of the

<PAGE>

         Premises without the prior written consent of Sublandlord. Provided,
         however that Subtenant shall have the right (upon receipt of final
         written consent by Landlord and Sublandlord) to utilize the exterior
         Building signage locations previously utilized by Iona Technologies,
         Inc.

                  (3) Subtenant shall not perform any act or carry on any
         practice which may injure the Premises or any other part of the
         Building.

                  (4) Subtenant shall, in its use of the Premises, comply with
         all applicable laws and rules, orders, regulations and requirements of
         all governmental and quasi-governmental authorities having or asserting
         jurisdiction and any insurer of Sublandlord or Landlord of all or any
         part of the Building.

         Notwithstanding the foregoing or any other provisions of this Sublease,
Subtenant shall not be responsible for compliance with any such laws,
regulations, or the like requiring (i) structural repairs or modifications or
(ii) repairs or modifications to the utilities or building service equipment or
(iii) installation of new building service equipment, such as fire detection or
suppression equipment, unless such repairs, modifications, or installations
shall (a) be due to Subtenant's particular manner of use of the Premises (as
opposed to office use and research and development associates with Subtenant's
business generally), or (b) be due to the negligence or willful misconduct of
Subtenant or any agent, employee, or contractor of Subtenant.

         7.2  INSTALLATIONS AND ALTERATIONS BY SUBTENANT.

         (A) Subtenant shall not make or perform, or permit the making or
performance of any alterations, improvements, additions or other physical
changes in or about the Premises (collectively, "Alterations") without
Sublandlord's prior written consent. Sublandlord agrees not to unreasonably
withhold its consent to any Alterations which are nonstructural, do not involve
the Building's systems and facilities and are not visible from outside the
Premises, provided that such Alterations do not reduce the value or utility of
the Building. All Alterations shall be done at Subtenant's expense and at such
times and in accordance with any reasonable rules and regulations established by
Sublandlord. Prior to making any Alterations, Subtenant (i) shall submit to
Sublandlord plans and specifications for each proposed Alteration, (ii) shall,
at its expense, obtain all permits, approvals and certificates required by any
governmental or quasi-governmental bodies, and (iii) shall furnish to
Sublandlord duplicate original policies of worker's compensation insurance
(covering all persons to be employed by Subtenant and Subtenant's contractors
and subcontractors in connection with such Alteration) and comprehensive public
liability (including property damage coverage) insurance in such form, with such
companies, for such periods and in such amounts as Sublandlord may reasonably
require, naming Sublandlord and its agents as additional insureds. All materials
and equipment to be incorporated in the Premises as a result of all alterations
or improvements shall be of first quality. No such materials or equipment shall
be subject to any lien, encumbrance, chattel mortgage, title retention or
security agreement. All work performed by Subtenant to the Premises shall be
done in a good and workmanlike manner and in compliance with all applicable laws
and regulations.

<PAGE>

         (B) All Alterations and all fixtures, paneling, partitions, railings,
equipment and like installations installed in the Premises at any time either by
Subtenant or by Sublandlord on Subtenant's behalf shall, upon installation,
become the property of Sublandlord (unless otherwise agreed in writing by
Sublandlord and Subtenant) and remain upon and be surrendered with the Premises
unless Sublandlord, by notice to Subtenant at either the time consent for the
installation of the Alterations is requested or at the expiration of the Term of
this Sublease, elects to relinquish Sublandlord's right thereto and to have them
removed by Subtenant, in which event, they shall be removed by Subtenant
promptly thereafter, at Subtenant's expense.

         (C) All trade fixtures, articles of personal property, and all business
machinery and equipment and furniture owned or installed by Subtenant solely at
its expense in the Premises shall remain the property of Subtenant and shall be
removed by Subtenant at any time prior to the expiration of this Sublease,
provided that Subtenant, at its expense, shall repair any damage to the Premises
or the Building caused by any installation and/or removal of Subtenant's
Removable Property.

         (D) Notice is hereby given that Sublandlord shall not be liable for any
labor or materials furnished or to be furnished to Subtenant and that no
mechanic's or other lien for any such labor or materials shall attach to or
affect the reversion or other estate or interest of Sublandlord in and to the
Premises. Whenever and as often as any mechanic's lien shall have been filed
against the Property based upon any act of, or for work claimed to have been
done for, or materials furnished to, Subtenant, or of, for or to anyone claiming
through Subtenant, Subtenant shall forthwith take such action, by bonding,
deposit or payment, as will remove or satisfy the lien.

                                  ARTICLE VIII

                            ASSIGNMENT AND SUBLETTING

         8.1 PROHIBITION. Subtenant covenants and agrees that neither this
Sublease nor the term and estate hereby granted, nor any interest herein or
therein, will be assigned (including, without limitation, by operation of law),
mortgaged, pledged, encumbered or otherwise transferred, and that neither the
Premises nor any part thereof will be encumbered in any manner by reason of any
act or omission on the part of Subtenant, or used or occupied or permitted to be
used or occupied by anyone other than Subtenant or for any use or purpose other
than a Permitted Use, or be sublet (which term, without limitation, shall
include granting of concessions, licenses and the like) in whole or in part,
without, in each instance, Subtenant having first received the express written
consent of Sublandlord. Sublandlord agrees that it will not unreasonably
withhold or delay consent to assignment, subletting or use by a third party if,
in Sublandlord's reasonable discretion, Sublandlord is reasonably satisfied as
to (i) the identity of such third party, (ii) the financial ability of such
third party, and (iii) the type of business that such third party proposes to
operate in the Premises. If this Sublease be assigned, or if the Premises or any
part thereof be sublet or occupied by anyone other than Subtenant, Sublandlord
may collect rent and other charges from the assignee, Subtenant or occupant, and
apply the net amount collected to the Fixed Rent and other charges herein
reserved, but no such assignment, subletting, occupancy or

<PAGE>

collection shall be deemed a waiver of this covenant, the acceptance of the
assignee, Subtenant or occupant as a Subtenant or a release of Subtenant from
the further performance by Subtenant of its obligations hereunder. The consent
by Sublandlord to an assignment or subletting shall in no way be construed to
relieve Subtenant or any successor from obtaining the express consent in writing
of Sublandlord to any further assignment or subletting.

         Notwithstanding anything to the contrary contained in this Sublease,
Subtenant may, without Sublandlord's prior written consent, but upon notice to
Sublandlord, sublet all or any portion of the Premises or assign Subtenant's
interest in this Sublease to (i) a subsidiary, affiliate, parent or other entity
to Subtenant which controls, is controlled by, or is under common control with,
Subtenant; (ii) a successor entity to Subtenant resulting from merger,
consolidation, non-bankruptcy reorganization, or government action; or (iii) a
purchaser of all or any significant portion of Subtenant's stock or assets.

         In any case where Sublandlord shall consent to such assignment,
subletting or use, Subtenant shall remain fully liable for Subtenant's
obligations under this Sublease, including, without limitation, the obligation
to pay the rent and other amounts provided under this Sublease. At Sublandlord's
election, it shall be a condition of the validity of any such assignment, that,
upon Sublandlord's request, the assignee shall agree directly with Sublandlord,
in form reasonably satisfactory to Sublandlord, to be bound by all the
obligations of Subtenant, including, without limitation, the obligation to pay
rent and other amounts provided under this Sublease and the covenant against
further assignment, subletting and use.

         8.2  OTHER REQUIREMENTS AND PROVISIONS.

         (A) No assignment of this Sublease shall be effective unless and until
Subtenant delivers to Sublandlord duplicate originals of the instrument of
assignment (wherein the assignee assumes the performance of Subtenant's
obligations under this Sublease) and any accompanying documents.

         (B) No sub-sublease of all or any part of the Premises shall be
effective unless and until Subtenant delivers to Sublandlord duplicate originals
of the instrument of sub-sublease and any accompanying documents. Any such
sub-sublease shall be subject and subordinate to this Sublease.

         (C) Sublandlord's consent to any assignment or sub-sublease shall
neither release Subtenant from its liability for the performance of Subtenant's
obligations hereunder during the balance of the Term of this Sublease nor
constitute its consent to any further assignment or sub-sublet of this Sublease.
If a sub-sublease to which Sublandlord has consented is assigned or all or any
portion of the Premises is further sublet without in each instance, the prior
consent of Sublandlord, then Subtenant shall immediately terminate such
sub-sublease, or arrange for the termination thereof, and proceed expeditiously
to have the occupant thereunder dispossessed.

         (D) Subtenant shall pay to Sublandlord, promptly upon demand therefor,
all reasonable costs and expenses (including, without limitation, reasonable
attorneys'

<PAGE>

fees and disbursements) incurred by Sublandlord in connection with any
assignment of this Sublease or sub-sublease of all or any part of the Premises.

         (E) Fifty percent (50%) of any profit resulting from any such
assignment or subletting shall be payable to Sublandlord, with the remaining
profit to be retained by Subtenant.

                                   ARTICLE IX

              RESPONSIBILITY FOR REPAIRS AND CONDITION OF PREMISES

         9.1 SUBLANDLORD REPAIRS AND MAINTENANCE. Except as otherwise provided
in this Sublease, Sublandlord shall not be responsible for making any
improvements or repairs to the Building. All costs incurred by Sublandlord
pursuant to the terms of this Section 9.1 or the terms of Section 6 of the
Master Lease shall be deemed Operating Expenses under Article VI.

         9.2  SUBTENANT'S AGREEMENT.

         (A) Subtenant will keep neat and clean and maintain in substantially
the same order, condition and repair the Premises and every part thereof
including, plumbing, mechanical, heating and HVAC serving exclusively the
Premises as such were in on the Commencement Date, reasonable wear and tear
excepted, and Subtenant shall surrender the Premises, at the expiration or
earlier termination of this Sublease, in such condition. Without limitation,
Subtenant shall maintain and use the Premises in accordance with all reasonable,
rules and regulations of Sublandlord, Landlord and all governmental agencies
having jurisdiction and shall, at Subtenant's own expense, obtain all permits,
licenses and the like required by applicable law. Subtenant shall be responsible
for the cost of repairs which may be made necessary by reason of damage to
common areas in the Building by Subtenant or its contractors or invitees, except
for damage due to fire or other casualty.

         (B) If repairs are required to be made by Subtenant pursuant to the
terms hereof and are not made within the time periods allowed hereunder,
Sublandlord may demand that Subtenant make the same forthwith, and, if Subtenant
refuses or neglects to commence such repairs and complete the same with
reasonable dispatch after such demand, Sublandlord may (but shall not be
required to) upon prior written notice to Subtenant make or cause such repairs
to be made at Subtenant's expense and shall not be responsible to Subtenant for
any loss or damage that may occur to Subtenant's stock or business by reason
thereof.

         9.3 HEAVY MACHINERY. Any moving of machinery or equipment by Subtenant
shall be at the sole risk and hazard of Subtenant, and Subtenant will exonerate,
indemnify and save Sublandlord harmless against and from any liability, loss,
injury, claim or suit resulting directly or indirectly from such moving.

         9.4 ELECTRICITY. The Premises is currently submetered for electrical
usage and Sublandlord has contracted directly with its electricity provider.
Sublandlord shall forward all invoices for the cost of such electric current to
the Subtenant each month. Subtenant shall remit payment for such invoices within
ten

<PAGE>

(10) days of receipt of same. The cost of such electric current shall be
Subtenant's sole cost and expense. Sublandlord shall not in any way be liable or
responsible to Subtenant for any loss, damage or expense which Subtenant may
sustain or incur if, during the Term of this Sublease, either the quantity or
character of electric current is changed or electric current is no longer
available or suitable for Subtenant's requirements. Subtenant shall, at
Subtenant's expense, purchase and install all lamps, tubes, bulbs, starters and
ballasts in the Premises.

         9.5 OTHER UTILITIES. Subtenant shall purchase and receive gas for the
Premises directly from the public utility company serving the Building.
Subtenant agrees to pay, as additional rent, all costs for water and sewerage
usage at the Premises within thirty (30) days of receipt of a bill from
Sublandlord or Landlord.

         9.6 INTERRUPTION OR CURTAILMENT OF SERVICES. Upon reasonable advance
notice to Subtenant (except in case of emergency), Sublandlord reserves the
right to temporarily interrupt, curtail, stop or suspend (a) the heating
services in the Building and (b) the operation of the plumbing and electric
systems in the Building, when necessary by reason of accident or emergency, or
for repairs, alterations, maintenance, replacements or improvements in the
reasonable judgment of Sublandlord desirable or necessary to be made, or by
reason of difficulty or inability in securing supplies or labor, or strikes, or
any other cause beyond the reasonable control of Sublandlord, whether such other
cause be similar or dissimilar to those hereinabove specifically mentioned,
until said cause has been removed. There shall be no diminution or abatement of
rent or other compensation due from Subtenant to Sublandlord hereunder, nor
shall this Sublease be affected or any of the Subtenant's obligations hereunder
reduced, and the Sublandlord shall have no responsibility or liability for any
such interruption, curtailment, stoppage, or suspension of services or systems
as in this Section 9.6 above provided, except that Sublandlord shall exercise
reasonable diligence to eliminate the cause of same. Sublandlord shall use all
commercially reasonable efforts to insure that such interruptions, curtailments,
stoppages or suspensions do not materially interfere with Subtenant's Permitted
Use.

                                    ARTICLE X

                             INDEMNITY AND INSURANCE

         10.1 SUBTENANT'S INDEMNITY. To the maximum extent this agreement may be
made effective according to law, Subtenant agrees to indemnify and save harmless
Sublandlord, Landlord and Sublandlord's agents, affiliates, contractors and the
employees of the foregoing from and against all claims of whatever nature
arising from any negligence of Subtenant or Subtenant's contractors, licensees,
invitees, agents, servants or employees or arising from any accident, injury or
damage whatsoever caused to any person, or to the property of any person,
occurring on account of or based upon the negligence or misconduct of Subtenant
or Subtenant's contractors, licensees, invitees, agents servants or employees or
arising from any breach by Subtenant of the terms and conditions of this
Sublease. This indemnity and hold harmless agreement shall include indemnity
against all costs, expenses and liabilities (including, but not limited to,
reasonable attorney's fees and disbursements) incurred in connection with any
such claim or proceeding

<PAGE>

brought thereon and the defense thereof. Subtenant's liability hereunder shall
survive any expiration or termination of this Sublease.

         10.2  INSURANCE.

         (A) Subtenant agrees to maintain in full force, from the date upon
which Subtenant first enters the Premises for any reason throughout the Term of
this Sublease and thereafter so long as Subtenant is in occupancy of any part of
the Premises, (i) "all risk" property insurance covering all present and future
Subtenant's Removable Property and Subtenant's improvements and betterments to a
limit of not less than the full replacement cost thereof and, (ii) a policy of
general liability and property damage insurance (including broad form
contractual liability, independent contractor's hazard and completed operations
coverage) in respect of the Premises and the conduct or operation of business
therein, with Sublandlord, Landlord and any permitted mortgagee under Section
15.13 hereof of which Subtenant has received written notice, (and such other
persons as are in privity of estate with Sublandlord as may be set out in notice
from time to time) named as an additional insured, and with limits of not less
than the amount of Public Liability Insurance specified in Section 1.1.
Subtenant shall deliver to Sublandlord certificates of insurance and receipts
evidencing payment of the premiums for such insurance on or before the
Commencement Date and annually thereafter. Each such policy shall be
non-cancelable and non-amendable with respect to Sublandlord and Sublandlord's
said designees without twenty (20) days' prior notice to Sublandlord.

         (B) Subtenant hereby waives and releases Sublandlord from any and all
liabilities, claims and losses on account of damage to Subtenant's Removable
Property for which Sublandlord is or may be held liable to the extent Subtenant
either is required to maintain insurance pursuant to Section 10.2(A) or actually
receives insurance proceeds on account thereof. Sublandlord hereby waives and
releases Subtenant from any and all liabilities, claims and losses on account of
damage to the Building for which Subtenant is or may be held liable to the
extent Sublandlord actually receives insurance proceeds on account thereof or is
required to maintain insurance pursuant to Section 10.5 of this Sublease. Each
party hereto shall secure waiver of subrogation endorsements from their
respective insurance carriers.

         10.3 SUBTENANT'S RISK. To the maximum extent this agreement may be made
effective according to law, Subtenant agrees to use and occupy the Premises and
to use such other portions of the Building as Subtenant is herein given the
right to use at Subtenant's own risk; and Sublandlord shall have no
responsibility or liability for any loss of or damage to Subtenant's Removable
Property or for any other property of any kind, nature and description which may
be in or upon the Premises or the Building. The provisions of this Section shall
be applicable from and after the execution of this Sublease and until the end of
the Term of this Sublease, and during such further period as Subtenant may use
or be in occupancy of any part of the Premises or of the Building.

         10.4 INJURY CAUSED BY THIRD PARTIES. To the maximum extent this
agreement may be made effective according to law, Subtenant agrees that
Sublandlord shall not be responsible or liable to Subtenant, or to those
claiming by,

<PAGE>

through or under Subtenant, for any loss or damage that may be occasioned by or
through the acts or omissions of any third parties and Sublandlord agrees that
Subtenant shall not be responsible or liable to Sublandlord, or to those
claiming by, through or under Sublandlord, for any loss or damage that may be
occasioned by or through the acts or omissions of any third parties.

                                   ARTICLE XI

                        SUBLANDLORD'S ACCESS TO PREMISES

         11.1 SUBLANDLORD'S RIGHTS. Sublandlord shall have the right upon
reasonable advance notice to enter the Premises at all reasonable hours for the
purpose of inspecting or making repairs to the Premises, and Sublandlord shall
also have the right to make access available at all reasonable hours to
prospective or existing mortgagees, purchasers or Subtenants of any part of the
Property. Notwithstanding the foregoing, Sublandlord shall have the right to
enter the Premises at any time without notice in the event of an emergency.

                                   ARTICLE XII

                              DAMAGE OR DESTRUCTION

         12.1 DAMAGE OR DESTRUCTION. Subject to the limitations of Section 17 of
this Sublease, the provisions of Sections 17.1, 17.2, 17.3 and 17.4 of the
Master Lease are incorporated herein by reference, PROVIDED, that Sublandlord
shall not, in any event, have an obligation to repair or restore the Premises in
the event of a casualty. Any reference to "Lessor" in any provision of the
Master Lease incorporated herein by reference shall mean, where the context
reasonably allows, "Sublandlord" as defined in this Sublease. Any reference to
"Lessee" in any provision of the Master Lease incorporated herein by reference
shall mean, where the context reasonably allows, "SubSubtenant" as defined in
this Sublease. Any reference to "Leased Premises" in any provision of the Master
Lease incorporated herein by reference shall mean, where the context reasonably
allows, "Premises" as defined in this Sublease. Any reference to "this Lease" in
any provision of the Master Lease incorporated herein by reference shall mean
this Sublease and not the Master Lease. To the extent that any provision in the
Master Lease incorporated herein by reference may conflict with or be
inconsistent with any provision of this Sublease not so incorporated from the
Master Lease, whether or not such inconsistency is expressly noted herein, the
provisions of this Sublease shall prevail.

                                  ARTICLE XIII

                                  CONDEMNATION

         13.1 CONDEMNATION. Subject to the limitations of Section 17 of this
Sublease, the provisions of Section 17A of the Master Lease is incorporated
herein by reference, PROVIDED, that Sublandlord shall not, in any event, have an
obligation to repair or restore the Premises in the event of a condemnation. Any
reference to "Lessor" in any provision of the Master Lease incorporated herein
by reference shall mean, where the context reasonably allows, "Sublandlord" as
defined in this

<PAGE>

Sublease. Any reference to "Lessee" in any provision of the Master Lease
incorporated herein by reference shall mean, where the context reasonably
allows, "SubSubtenant" as defined in this Sublease. Any reference to "Leased
Premises" in any provision of the Master Lease incorporated herein by reference
shall mean, where the context reasonably allows, "Premises" as defined in this
Sublease. Any reference to "this Lease" in any provision of the Master Lease
incorporated herein by reference shall mean this Sublease and not the Master
Lease. To the extent that any provision in the Master Lease incorporated herein
by reference may conflict with or be inconsistent with any provision of this
Sublease not so incorporated from the Master Lease, whether or not such
inconsistency is expressly noted herein, the provisions of this Sublease shall
prevail.

                                   ARTICLE XIV

                                     DEFAULT

         14.1  SUBTENANT'S DEFAULT.

         (A) If at any time subsequent to the date of this Sublease any one or
more of the following events (herein referred to as a "Default of Subtenant")
shall happen:

                  (1) Subtenant shall fail to pay Fixed Rent, additional rent or
         any other amounts payable under this Sublease, when due and such
         failure shall continue for five (5) days after the date such Fixed
         Rent, additional rent or any other amounts payable under this Lease are
         due, PROVIDED, however, if Subtenant shall fail to pay Fixed Rent,
         additional rent or any other amounts payable under this Lease when due
         more than one (1) time during any Lease year of the Term (or Extension
         Term, if applicable), then Sublandlord shall have the option of
         declaring a Default of Subtenant immediately upon such failure, without
         regard to the aforementioned five (5) day grace period; or

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

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

                  (4) Subtenant shall make an assignment for the benefit of
         creditors or shall file a voluntary petition in bankruptcy or shall be
         adjudicated bankrupt or insolvent, or shall file any petition or answer
         seeking any reorganization, arrangement, composition, readjustment,
         liquidation, dissolution or similar relief for itself under any present
         or future Federal, State, or other statute, law or regulation for the
         relief of debtors, or shall seek or consent to or acquiesce in the
         appointment of any trustee, receiver or liquidator of

<PAGE>

         Subtenant or of all or any substantial part of its properties, or shall
         admit in writing its inability to pay its debts generally as they
         become due; or

                  (5) A petition shall be filed against Subtenant in bankruptcy
         or under any other law seeking any reorganization, arrangement,
         composition, readjustment, liquidation, dissolution, or similar relief
         under any present or future Federal, State or other statute, law or
         regulation and shall remain undismissed or unstayed for an aggregate of
         sixty (60) days (whether or not consecutive), or if any debtor in
         possession trustee, receiver or liquidator of Subtenant or of all or
         any substantial part of its properties or of the Premises shall be
         appointed without the consent or acquiescence of Subtenant, and such
         appointment shall remain unvacated or unstayed for an aggregate of
         sixty (60) days (whether or not consecutive);

then in any such case (a) if such Default of Subtenant shall occur prior to
the Commencement Date, this Sublease shall IPSO FACTO, and without further
act on the part of the Sublandlord, terminate, and (b) if such Default of
Subtenant shall occur after the Commencement Date, Sublandlord or
Sublandlord's agent may immediately, or at any time thereafter, without
demand or notice, enter into and upon the Premises, or any part thereof in
the name of the whole, and repossess the same and upon such entry this
Sublease shall terminate or Sublandlord may terminate this Sublease at any
time thereafter by notice to Subtenant, specifying a date not less than
fifteen (15) days after the giving of such notice on which this Sublease
shall terminate and this Sublease shall come to an end on the date specified
therein as fully and completely as if such date were the date herein
originally fixed for the expiration of the Term of this Sublease (Subtenant
hereby waiving any rights of redemption under MGL c. 186 Section 11), and
Subtenant will then quit and surrender the Premises to Sublandlord, but
Subtenant shall remain liable as hereinafter provided.

         (B) If this Sublease shall have been terminated as provided in this
Article, or if any execution or attachment shall be issued against Subtenant or
any of Subtenant's property whereupon the Premises shall be taken or occupied by
someone other than Subtenant, then Sublandlord may, without notice, reenter the
Premises, either by summary proceedings, ejectment or otherwise, and remove and
dispossess Subtenant and all other persons and any and all property from the
Premises, as if this Sublease had not been made, and Subtenant hereby waives the
service of notice of intention to reenter or to institute legal proceedings to
that end.

         (C) In the event of any termination of this Sublease, Subtenant shall
pay the Fixed Rent, additional rent and all other amounts payable hereunder up
to the time of such termination, and thereafter Subtenant, until the end of what
would have been the Term of this Sublease in the absence of such termination,
and whether or not the Premises shall have been relet, shall be liable to
Sublandlord for, and shall pay to Sublandlord, as liquidated current damages,
the Fixed Rent, additional rent and all other amounts payable hereunder had such
termination not occurred, less the net proceeds, if any, of any reletting of the
Premises, after deducting all reasonable expenses in connection with such
reletting, including, without limitation, all repossession costs, brokerage
commissions, legal expenses, advertising and marketing costs, expenses of
employees, alteration and Subtenant improvement costs and expenses of
preparation for such reletting. Subtenant shall pay such

<PAGE>

damages to Sublandlord monthly on the days on which the Fixed Rent and
additional rent would have been payable hereunder had this Sublease not been
terminated.

         (D) At any time after the termination of this Sublease, whether or not
Sublandlord shall have collected any damages pursuant to Section 14.1(C), as
liquidated final damages, and in lieu of all damages payable by Subtenant
pursuant to Section 14.1(C) thereafter, at Sublandlord's election, Subtenant
shall pay to Sublandlord an amount which at the time of such election represents
the then value of the excess, if any, of (1) the Fixed Rent, additional rent and
all other amounts which would have been payable by Subtenant hereunder
(conclusively presuming the annual payments with respect to real estate taxes to
be the same as were payable for the preceding year) for the period commencing
with the date of Sublandlord's election and ending with the date contemplated as
the expiration date hereof if this Sublease had not so terminated, over (2) the
aggregate fair rental value of the Premises for the same period.

         (E) In case of any Default of Subtenant, reentry or expiration and
dispossession by summary proceedings or otherwise, Sublandlord may (1) relet the
Premises or any part or parts thereof, either in the name of Sublandlord or
otherwise, for a term or terms which may at Sublandlord's option be equal to or
less than or exceed the period which would otherwise have reasonably constituted
the balance of the Term of this Sublease and may grant reasonable concessions of
free rent to the extent that Sublandlord considers advisable and necessary to
relet the same, and (2) may make such alterations, repairs and decoration in and
to the Premises as Sublandlord in its reasonable judgment considers advisable
and necessary for the purpose of reletting the Premises, and the making of such
alterations, repairs and decorations shall not operate or be construed to
release Subtenant from liability hereunder. Sublandlord shall in no event be
liable in any way whatsoever for failure to relet the Premises, or in the event
that the Premises are relet, for failure to collect the rent under such
reletting. Subtenant hereby expressly waives any and all rights of redemption
granted by or under any present or future laws in the event of Subtenant being
evicted or dispossessed, or in the event of Sublandlord obtaining possession of
the Premises, by reason of the violation by Subtenant of any of the covenants
and conditions of this Sublease.

         (F) The specified remedies to which Sublandlord may resort hereunder
are not intended to be exclusive of any remedies or means of redress to which
Sublandlord may at any time be entitled lawfully, and Sublandlord may invoke any
remedy (including the remedy of specific performance) allowed at law or in
equity as if specific remedies were not herein provided.

         (G) All reasonable costs and expenses incurred by or on behalf of
Sublandlord (including, without limitation, reasonable attorneys' fees and
expenses) in enforcing its rights hereunder or occasioned by any Default of
Subtenant shall be paid by Subtenant promptly upon demand.

                                   ARTICLE XV

                            MISCELLANEOUS PROVISIONS

<PAGE>

         15.1  EXTRA HAZARDOUS USE.

         (A) Subtenant covenants and agrees that Subtenant will not do or permit
anything to be done in or upon the Premises, or bring in anything or keep
anything therein, which shall increase the rate of property or liability
insurance of the Premises or of the Building above the standard rate applicable
to Premises being occupied for Permitted Uses; and Subtenant further agrees
that, in the event that Subtenant shall do any of the foregoing, Subtenant will
promptly pay to Sublandlord, on demand, any such increase resulting therefrom.

         (B) Subtenant shall not (either with or without negligence) cause or
permit the escape, disposal or release of any hazardous substances, or
materials. Subtenant shall not allow the storage or use of such hazardous
substances or materials in any manner, nor allow to be brought into any portion
of the Building any such hazardous materials or substances, which are typically
used in connection with Subtenant's Permitted Use and in full compliance with
applicable environmental laws. Subtenant shall not store any flammable
substances in the Premises, unless such flammable substances are stored in areas
with in-rack sprinkling. Without limitation, hazardous substances and materials
shall include those described in the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended, 42 U.S.C. Section 9601 et
seq., M.G.L. Chapter 21E and any other applicable federal, state or local laws
and the regulations adopted under these acts ("Hazardous Substances"). If any
lender or governmental agency shall ever require testing to ascertain whether or
not there has been any release of hazardous materials as a result of a breach by
Subtenant of the provisions of this Section 15.1(B), then the reasonable costs
thereof shall be reimbursed by Subtenant to Sublandlord upon demand as
additional charges. In addition, Subtenant shall execute affidavits,
representations and the like from time to time at Sublandlord's reasonable
request concerning Subtenant's best knowledge and belief regarding the presence
of hazardous substances or materials on the Premises. In all events, Subtenant
shall indemnify Sublandlord in the manner provided in Section 10.1 hereof from
any release of hazardous materials on the Premises occurring while Subtenant is
in possession (except if caused by Sublandlord or persons acting under the
direction of Sublandlord), or elsewhere if caused by Subtenant or persons acting
under Subtenant. The within covenants shall survive the expiration or earlier
termination of the Term of this Sublease.

         15.2 WAIVER. The failure of either Sublandlord or Subtenant to insist
in any one or more instances upon the strict performance of any one or more of
the obligations of this Sublease, or to exercise any election herein contained,
shall not be construed as a waiver or relinquishment for the future of the
performance of such one or more obligations of this Sublease or of the right to
exercise such election, and such right to insist upon strict performance shall
continue and remain in full force and effect with respect to any subsequent
breach, act or omission. The receipt by Sublandlord of Fixed Rent, additional
rent or other payments due hereunder or partial payments thereof with knowledge
of breach by Subtenant of any obligation of this Sublease shall not be deemed a
waiver of such breach.

          15.3 COVENANT OF QUIET ENJOYMENT. Sublandlord covenants that, if
Subtenant shall timely perform all of its obligations hereunder, then, subject
to the provisions of this Sublease, Subtenant shall, during the Term of this
Sublease,

<PAGE>

peaceably and quietly occupy and enjoy the full possession of the Premises
without hindrance by Sublandlord or any party claiming through or under
Sublandlord.

         15.4  FORCE MAJEURE, ETC.

         (A) If either Subtenant or Sublandlord is in any way delayed or
prevented from performing any of its obligations under this Sublease (excluding
any monetary obligations of Subtenant, including without limitation Subtenant's
obligation to pay Fixed Rent and additional rent) due to fire, act of God,
governmental act or failure to act, strike, labor dispute, inability to procure
materials, war or any other cause beyond such party's reasonable control
(whether similar or dissimilar to the foregoing events), then the time for
performance of such obligation shall be excused for the period equal to the
period of such delay or prevention and extended for a period equal to the period
of such delay or prevention.

         (B) In no event shall either party be liable to the other for any
indirect or consequential damages suffered by either from any cause whatsoever.

         15.5  ASSIGNMENT OF RENTS AND TRANSFER OF TITLE.

         (A) If Sublandlord shall assign Sublandlord's interest in this Sublease
or in the rents payable hereunder to the holder of a mortgage covering the
Premises (regardless of whether or not such assignment is conditional in
nature), then such assignment shall not be construed as an assumption by the
assignee of any of the obligations of Sublandlord hereunder unless such assignee
(1) by notice sent to Subtenant, specifically otherwise elects, or (2)
forecloses on its mortgage, or (3) takes possession of the Premises.

         (B) In the event of any transfer of Sublandlord's interest in the
Master Lease, Sublandlord shall thereafter be released from the performance and
observance of all covenants and obligations hereunder occurring after the date
of such transfer and the transferee shall be deemed the Sublandlord under this
Sublease from and after the date of such transfer.

         15.6 RULES AND REGULATIONS. Subtenant shall abide by all reasonable
rules and regulations reasonably established by Sublandlord or Landlord from
time to time for the operation of the Building. Sublandlord agrees to use
reasonable efforts to insure that any such rules and regulations are uniformly
enforced, but Sublandlord shall not be liable to Subtenant for the violation of
any such rules or regulations by any other subtenant or occupant of the Building
or persons conducting business with such subtenant or occupant.

         15.7 ADDITIONAL CHARGES. If Subtenant shall fail to pay when due any
sums under this Sublease, Sublandlord shall have the same rights and remedies as
Sublandlord has hereunder for failure to pay Fixed Rent.

         15.8 INVALIDITY OF PARTICULAR PROVISIONS. If any provision of this
Sublease or the application thereof to any person or circumstance shall, to any
extent, be invalid or unenforceable, then the remainder of this Sublease and the
application of such provision to persons or circumstances other than those as to
which it is invalid or unenforceable shall not be affected thereby.

<PAGE>

         15.9 PROVISIONS BINDING. Except as herein otherwise provided, the
provisions of this Sublease shall be binding upon and shall inure to the benefit
of the parties hereto and each of their respective successors and assigns,
subject to the provisions herein restricting assignment or subletting.

         15.10 NOTICES. All notices or other permitted or required
communications hereunder shall be in writing and shall be deemed duly given when
delivered in person (with receipt therefor), or when sent by Express Mail or
overnight courier service (provided a receipt will be obtained) or by certified
or registered mail, return receipt requested, postage prepaid to the following
addresses:

         If to Sublandlord, addressed to Sublandlord at Sublandlord's Address
(or to such other address or addresses as may from time to time hereafter be
designated by Sublandlord by notice).

         If to Subtenant, addressed to Subtenant at the following address:

                  Celarix, Inc.
                  60 Aberdeen Avenue
                  Cambridge, Massachusetts
                  Attention:  Mark D. Shooman
                  Telephone:  (617) 367-7908
                  Facsimile:  (617) 367-1562

         15.11 WHEN SUBLEASE BECOMES BINDING. The submission of this document
for examination and negotiation does not constitute an offer to Sublease, or a
reservation of, or option for, the Premises, and this document shall become
effective and binding only upon the execution and delivery hereof by both
Sublandlord and Subtenant. All negotiations, consideration, representations and
understandings between Sublandlord and Subtenant are incorporated herein and
this Sublease expressly supersedes any proposals or other written documents
relating hereto. This Sublease may be modified or altered only by written
agreement signed by Sublandlord and Subtenant, and no act or omission of any
employee or agent of Sublandlord shall alter, change or modify any of the
provisions hereof. This Sublease shall not be recorded.

         15.12 PARAGRAPH HEADINGS. The paragraph headings throughout this
Sublease are for convenience and reference only, and the words contained therein
shall in no way be held to explain, modify, amplify or aid in the
interpretation, construction or meaning of the provisions of this Sublease.

         15.13  RIGHTS OF MORTGAGEE AND GROUND LESSOR.

         (A) This Sublease is subject and subordinate to the lien, provisions,
operation and effect of all mortgages, deeds of trust, ground leases or other
security instruments which may now or hereafter encumber the Building, the
Master Lease or the Land (collectively, "Mortgages"; individually, "Mortgage"),
to all funds and indebtedness intended to be secured thereby, and to all
renewals, extensions, modifications, recastings or refinancings thereof. The
holder of any Mortgage to which this Sublease is subordinate shall have the
right (subject to any required approval of the holder of any superior Mortgage)
at any time to declare this

<PAGE>

Sublease to be superior to the lien, provisions, operation and effect of such
Mortgage and Subtenant shall execute, acknowledge and deliver all documents
required by such holder in confirmation thereof provided such documents are in
form and substance reasonably satisfactory to Subtenant.

         (B) In confirmation of the foregoing subordination, Subtenant shall
within fifteen (15) days of Sublandlord's request execute any requisite or
appropriate document in the form provided by Sublandlord, Landlord or their
respective mortgagees. If the Property is sold at foreclosure or transferred by
a deed-in-lieu of foreclosure, then, at the request of such purchaser, Subtenant
shall attorn to such purchaser and shall recognize such purchaser as the
landlord under the Master Lease. If the Sublandlord's interest in the Master
Lease is sold at foreclosure or transferred by a deed-in-lieu of foreclosure,
then, at the request of such assignee, Subtenant shall attorn to such assignee
and shall recognize such assignee as sublandlord under this Sublease. Upon such
attornment, such purchaser or assignee (as the case may be) shall not be (1)
bound by any payment of the Fixed Rent or additional payments due hereunder for
more than one (1) month in advance, (2) bound by any amendment of this Sublease
made without the consent of the holder of each Mortgage existing as of the date
of such amendment provided Subtenant had notice of such Mortgage, (3) liable for
damages for any breach, act or omission of any prior Sublandlord, and (4)
subject to any offsets or defenses which Subtenant might have against any prior
Sublandlord. Within fifteen (15) days after the request of such purchaser,
Subtenant shall execute, acknowledge and deliver any reasonable requisite or
appropriate document submitted to Subtenant confirming such attornment
agreement.

         (C) After Subtenant receives notice from any person, firm or other
entity that it holds a Mortgage on the Building, the Master Lease or the
Property, no notice from Subtenant to Sublandlord alleging any default by
Sublandlord shall be effective unless and until a copy of the same is given to
such holder, provided that Subtenant shall have been furnished with the name and
address of such holder. Any such holder shall have thirty (30) days after its
receipt of notice from Subtenant of a default by Sublandlord under this Sublease
to cure such default before Subtenant may exercise any remedy hereunder. The
curing of any of Sublandlord's defaults by such holder shall be treated as
performance by Sublandlord.

         (D) Sublandlord shall use all commercially reasonable efforts to obtain
a recognition/non-disturbance agreement from Landlord's fee mortgage.

         15.14 ESTOPPEL CERTIFICATES. At any time and from time to time upon not
less than fifteen (15) days prior written notice, each of the parties hereto
(and in the case of Subtenant each sub-subtenant or assignee of Subtenant or
occupant of the Premises) shall execute, acknowledge and deliver to the other
party and/or any other person or entity designated by either party, an estoppel
certificate (1) certifying that this Sublease is unmodified and in full force
and effect (or if there have been modifications, that this Sublease is in full
force and effect as modified and stating the modifications), (2) stating the
dates to which the rent and any other charges have been paid, (3) stating
whether or not, to the best of Subtenant's knowledge, Sublandlord is in default
in the performance of any obligation of Sublandlord contained in this Sublease,
and, if so, specifying the nature of such default, (4) stating the address to
which notices are to be sent, and (5) certifying to

<PAGE>

such other matters as Sublandlord may reasonably request. Subtenant and
Sublandlord acknowledge that time is of the essence to the delivery of such
statements. Upon request, Subtenant agrees to furnish Sublandlord with
Subtenant's current annual reports and any other financial information of
Subtenant as Sublandlord may request from time to time.

         15.15 REMEDYING DEFAULTS. Sublandlord shall have the right, but shall
not be required, to pay such sums or perform such acts which may be necessary or
appropriate by reason of the failure or neglect of Subtenant to perform any of
its obligations under this Sublease beyond any applicable notice and grace
period hereunder. If Sublandlord, in connection with the foregoing, makes any
reasonable expenditures or incurs any obligations for the payment of money,
Subtenant agrees to pay to Sublandlord upon demand all such sums, together with
interest thereon at a rate equal to five percent (5%) over the rate of interest
reported from time to time in the Wall Street Journal as being the "prime rate"
then in effect. Any payment of Fixed Rent, additional rent or other amounts
payable hereunder, not paid when due shall, at the option of Sublandlord, bear
interest from the due date thereof at a rate equal to five percent (5%) over the
rate of interest reported from time to time in the Wall Street Journal as being
the "prime rate" then in effect and shall be payable by Subtenant to Sublandlord
on demand by Sublandlord. Notwithstanding anything to the contrary contained
herein, the interest to be paid by Subtenant to Sublandlord hereunder shall be
limited to the then maximum legal rate thereof.

         15.16 HOLDING OVER. If Subtenant does not immediately surrender the
Premises upon the expiration or earlier termination of the Term of this
Sublease, then Subtenant shall become a Subtenant by the month and the rent
shall be increased to 150% of the monthly installments of Fixed Rent, additional
rent and all other amounts that would have been payable pursuant to the
provisions of this Sublease if the Term of this Sublease had continued during
such holdover period. Such rent shall be computed on a monthly basis and shall
be payable on the first day of such holdover period and the first day of each
calendar month thereafter during such holdover period until the Premises have
been vacated. Sublandlord's acceptance of such rent shall not in any manner
adversely affect Sublandlord's other rights and remedies, including
Sublandlord's right to evict Subtenant and to recover damages.

         15.17 SURRENDER OF PREMISES. Upon the expiration or earlier termination
of the Term of this Sublease, Subtenant shall peaceably quit and surrender to
Sublandlord the Premises in neat and clean condition and in substantially the
same order, condition and repair as the Premises were in on the Commencement
Date, together with all alterations, additions and improvements which may have
been made or installed in, on or to the Premises prior to or during the Term of
this Sublease (subject, however, to the provisions of Section 7.2(D)), excepting
only ordinary wear and use, eminent domain, and damage by fire or other casualty
for which, under other provisions of this Sublease, Subtenant has no
responsibility of repair or restoration. Subtenant shall remove all of
Subtenant's Removable Property and all items specified by Sublandlord pursuant
to Section 7.2(D) and shall, at its expense, repair and restore the Premises to
the condition existing prior to installation and repair any damage to the
Premises or the Building due to such removal. Any of Subtenant's Removable
Property which shall remain in the Building or on the Premises after the
expiration or termination of this Sublease

<PAGE>

shall be deemed conclusively to have been abandoned, and either may be retained
by Sublandlord as its property or may be disposed of, at Subtenant's sole cost
and expense, in such manner as Sublandlord may see fit. Subtenant hereby agrees
that the furniture existing in the reception area of the Premises as of the
Commencement Date is the sole property of Sublandlord and shall remain on the
Premises after the expiration or earlier termination of this Sublease.

                                   ARTICLE XVI

                                    BROKERAGE

         16.1 BROKERAGE. Sublandlord and Subtenant each represent to the other
that it has dealt with no broker in connection with this Sublease other than
State Financial Services and CB Richard Ellis/Whittier Partners (the
"Broker(s)"). Each of Sublandlord and Subtenant shall indemnify and hold the
other party harmless from and against any liability and expense (including
reasonable attorneys' fees and disbursements) for any other brokerage commission
or finder's fee based on alleged actions of the party making the indemnity or
its agents or representatives. Each party's liability hereunder shall survive
any expiration or termination of this Sublease. Sublandlord agrees that it shall
be solely responsible for any fee or commission due to the Broker(s) in
connection with this Sublease.

                                  ARTICLE XVII

                               EXCULPATORY CLAUSE

         17.1  INTENTIONALLY DELETED.

         17.2 ACTIONS AGAINST SUBLANDLORD. In any claim made by Subtenant
against Sublandlord alleging that Sublandlord has acted unreasonably where
Sublandlord had an obligation to act reasonably, Subtenant shall have no right
to recover damages from Sublandlord and Subtenant's sole and exclusive recourse
against Sublandlord shall be an action seeking specific performance of
Sublandlord's obligation to act reasonably.

         17.3 PERFORMANCE BY LANDLORD; PERFORMANCE BY SUBLANDLORD UNDER MASTER
LEASE.

                  17.3.1 LANDLORD PERFORMANCE OF CERTAIN OBLIGATIONS. It is
understood and agreed that all work to be furnished, repairs to be made and
services to be furnished pursuant to any provision of the Master Lease
incorporated herein by reference will in fact be furnished or made by the
Landlord, subject, however, to any applicable terms of the Master Lease.

                  17.3.2 NO LIABILITY FOR LANDLORD PERFORMANCE Sublandlord shall
not be liable to Subtenant, nor shall Subtenant's obligations hereunder be
impaired or the performance thereof be excused, because of any failure or delay
on the Landlord's part in furnishing any such work or services or in making any
such repairs. Notwithstanding the foregoing, Sublandlord will use commercially
reasonable efforts to enforce its rights under the Master Lease on behalf of
Subtenant. As used herein the term "commercially reasonable efforts"

<PAGE>

shall not include, INTER ALIA, the institution of litigation or arbitration, or
the payment of money or other consideration.

                  17.3.3 ENFORCEMENT OF LANDLORD OBLIGATIONS. If the Landlord
shall default in the performance of any of its obligations under the Master
Lease (as such sections of the Master Lease are expressly incorporated herein by
reference) and such Landlord default directly affects the Premises or
Subtenant's use of the Premises, Subtenant shall notify Sublandlord and
Sublandlord shall make demand upon Landlord and, if necessary, shall institute
any appropriate action or proceeding against the Landlord for the enforcement of
any such obligations of the Landlord reasonably required by Subtenant in
exercising the rights granted in this Section 17.3.3. Subtenant shall reimburse
Sublandlord for Sublandlord's costs and expenses (including reasonable
attorneys' fees) incurred by Sublandlord in enforcing any such obligations on
Subtenant's behalf.

                  17.3.4 NO MASTER LEASE DEFAULT. Sublandlord covenants and
agrees that Sublandlord will not do anything which would constitute a default
under the provisions of the Master Lease, whether or not expressly incorporated
by reference in this Sublease, or omit to do anything which Sublandlord is
obligated to do under the terms of this Sublease which would constitute a
default under the Master Lease, if and to the extent that any such default would
affect Subtenant's right to use and occupy the Premises in the manner set forth
in this Sublease.

                  17.3.5 CONSENT OF LANDLORD. No action or lack of action by
Landlord shall be deemed to be improper if Landlord, under the provisions of the
Master Lease, is required to obtain the approval of the Landlord before acting
and the Landlord's approval is refused or delayed.

                                  ARTICLE XVIII

                        SUBMISSION TO JURISDICTION, ETC.

         18.1 GOVERNING LAW. This Sublease shall be construed in accordance with
the laws of the Commonwealth of Massachusetts. All actions or proceedings
relating, directly or indirectly, to this Sublease shall be litigated only in
courts located within the Commonwealth of Massachusetts. Subtenant, its partners
and their successors and assigns hereby subject themselves to the jurisdiction
of any state or federal court located within the Commonwealth of Massachusetts.

         18.2 RECOVERY OF FEES. In the event of any action or proceeding brought
by either party against the other under this Lease, the prevailing party shall
be entitled to recover all costs and expenses including its attorneys' fees in
such action or proceeding in such amount as the court may adjudge reasonable.
The prevailing party shall be determined by the court based upon an assessment
of which party's major arguments made or positions taken in the proceedings
could fairly be said to have prevailed over the other party's major arguments or
positions on major disputed issues in the court's decision. If the party which
shall have commenced or instituted the action, suit or proceeding shall dismiss
or discontinue it without the concurrence of the other party, such other party
shall be deemed the prevailing party.

<PAGE>

                                   ARTICLE XIX

                                SECURITY DEPOSIT

         19.1 PAYMENT OF SECURITY DEPOSIT. Simultaneous with the execution of
this Sublease, Subtenant shall pay the Security Deposit as security for the
faithful performance and observation by Subtenant of the terms, conditions and
provisions of this Sublease. Sublandlord shall have no obligation to segregate
the Security Deposit or to pay any interest thereon. In the event Subtenant
defaults in respect of any of the terms, conditions or provisions of this
Sublease, (A) Sublandlord may apply all or part of the Security Deposit to the
extent required for payment of any Fixed Rent, additional rent or other sums as
to which Subtenant is in default or for any sum which Sublandlord may expend or
may be required to expend by any reason of Subtenant's default in respect of any
terms, covenants and conditions of this Sublease, including, but not limited to,
any damages or deficiency in the reletting of the Premises, whether such damages
or deficiency accrue before or after summary proceedings or other re-entry by
Sublandlord, without thereby waiving any other rights or remedies of Sublandlord
with respect to such default, and (B) Sublandlord shall hold the remainder of
the Security Deposit, if any, as security for the faithful performance and
observance by Subtenant of the terms, covenants and conditions of this Sublease
on Subtenant's part to be observed and performed with the same rights as
hereinabove set forth to apply the same in the event of any further default by
Subtenant under this Sublease. If Sublandlord applies any part of the Security
Deposit, Subtenant shall upon demand immediately deposit with Sublandlord a sum
equal to the amount so applied as security as aforesaid, failing which
Sublandlord shall have the same rights and remedies as for the non-payment of
Fixed Rent, and additional rent beyond the applicable grace period. If Subtenant
shall fully and faithfully comply with all of the terms, provisions, covenants
and conditions of this Sublease, the Security Deposit or any remaining portion
thereof, together with any portion of any other sums then held by Sublandlord as
such security, shall be returned to Subtenant after the expiration of this
Sublease and after delivery of the entire possession of the Premises to
Sublandlord.

         Notwithstanding the foregoing, Subtenant may elect to pay Sublandlord a
portion of the Security Deposit, such portion not to exceed $150,000.00 in the
form of a clean, irrevocable, freely transferable letter of credit, acceptable
to Sublandlord and to Sublandlord's mortgage lender (with the balance of the
Security Deposit to be paid in cash), as security for the performance of the
obligations of Subtenant hereunder. The letter of credit shall be from a bank
that will honor the letter of credit in Boston, Massachusetts, and is otherwise
reasonably acceptable to Sublandlord and its mortgage lender. If there is a
material adverse change at any time in the financial condition of the bank
issuing the letter of credit, Sublandlord may require Subtenant to provide a
substitute letter of credit from another reasonably acceptable bank within
thirty (30) days after request, and if not so replaced Sublandlord may draw the
letter of credit and hold the proceeds as set forth below. The letter of credit
shall be renewed at least thirty (30) days prior to its expiration from time to
time, and, if not so renewed, Sublandlord or its mortgage lender may draw the
letter of credit and hold the proceeds as set forth below. If Subtenant shall
fail to perform any of its obligations under this Sublease,

<PAGE>

Sublandlord or its mortgage lender may, but shall not be obliged to, (i) draw
the entire amount of the letter of credit, (ii) hold the proceeds of the letter
of credit as a cash Security Deposit and/or (iii) apply the proceeds of the
letter of credit to the extent necessary to cure the default, and within three
(3) days following request by Sublandlord, Subtenant shall, by a cash payment
made to Sublandlord, reinstate the Security Deposit to the amount thereof at the
time of the default. Any transfer of the letter of credit to Sublandlord's
successors or assigns shall be at the sole cost and expense of Subtenant and, if
the issuer of the letter of credit does not promptly issue a new letter of
credit in favor of Sublandlord's successors and assigns, Subtenant have the
right to draw the entire amount of the letter of credit as a cash Security
Deposit.

         Provided Subtenant is not then in default of any of its obligations
under this Sublease, the Security Deposit shall be reduced according to the
schedule attached hereto as EXHIBIT B. The amount by which the Security Deposit
is reduced on the third and fourth anniversary of the Rent Commencement Date of
this Sublease (pursuant to EXHIBIT B) shall be applied by Sublandlord towards
the Monthly Rent for the first month's Fixed Rent for the third and fourth years
of the Term.

         19.2 NO ENCUMBRANCES. Subtenant covenants that it shall not assign or
encumber or attempt to assign or encumber any part of the security and that
neither Sublandlord nor its successors or assigns shall be bound by any such
assignment, encumbrance, attempted assignment or attempted encumbrance.

         19.3 TRANSFER OF SECURITY DEPOSIT. In the event of any sale,
transfer or leasing of Sublandlord's interest in the Property to a vendee,
transferee or lessee, Sublandlord shall have the right to transfer the
Security Deposit or any remaining portion thereof to the vendee, transferee
or lessee, and Sublandlord shall thereupon be released by Subtenant from all
liability for the return or payment thereof, and Subtenant shall look solely
to the new Sublandlord for the return or payment of same. Subtenant agrees to
execute any documents reasonably requested by Sublandlord to acknowledge and
effect the transfer of the Security Deposit. The provisions of this Section
19.3 shall apply to every subsequent sale, transfer or leasing.

                [THE REST OF THIS PAGE INTENTIONALLY LEFT BLANK]

<PAGE>

         IN WITNESS WHEREOF, each of Sublandlord and Subtenant has caused this
Sublease to be duly executed as of the date first written above

                                  SUBLANDLORD:

                                  ROWECOM INC.


                                  By: /s/ Richard R. Rowe
                                     -----------------------------------------
                                       Name:   Richard R. Rowe
                                             -----------------------------------
                                       Title:  President & CEO
                                              ----------------------------------

                                  SUBTENANT:

                                  CELARIX, INC.


                                  By: /s/ [ILLEGIBLE]
                                     -----------------------------------------
                                       Name:   [ILLEGIBLE]
                                             -----------------------------------
                                       Title:  VP & CFO
                                              ----------------------------------

<PAGE>

                                LANDLORD CONSENT

         The undersigned, as Landlord under the Master Lease, hereby consents to
this Sublease. The undersigned agrees that the $100,000 portion of the tenant
improvement allowances allocated under the Master Lease to the Premises
hereunder shall be available for Subtenant's use on all of the same terms and
conditions as are set forth in Section 3.2.1 of the Master Lease. The
undersigned further agrees that Subtenant shall have the right to utilize the
exterior building signage locations at the Building and on the Property
previously utilized by Iona Technologies, Inc.

                                       Western Properties Master LLC


                                       /s/  Allan R. Jones
                                       ----------------------------------
                                       Name:      Allan R. Jones
                                       Office:    Manager - Member

<PAGE>

                         LIST OF SCHEDULES AND EXHIBITS

         SCHEDULE 1                 Master Lease

         EXHIBIT A                  Floor Plan Showing Premises

         EXHIBIT B                  Security Deposit Reduction Schedule

<PAGE>

                                    EXHIBIT B

                       SECURITY DEPOSIT REDUCTION SCHEDULE
<TABLE>
<CAPTION>

---------------------------- -------------------------- -------------------------- --------------------------
                                       CASH                 LETTER OF CREDIT                 TOTAL
---------------------------- -------------------------- -------------------------- --------------------------
<S>                                  <C>                        <C>                        <C>
          Year 1                     $100,000                   $150,000                   $250,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 2                     $100,000                   $150,000                   $250,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 3                      $50,000                   $150,000                   $200,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 4                        $0                      $150,000                   $150,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 5                        $0                      $100,000                   $100,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 6                        $0                      $100,000                   $100,000
---------------------------- -------------------------- -------------------------- --------------------------
          Year 7                        $0                      $100,000                   $100,000
---------------------------- -------------------------- -------------------------- --------------------------
</TABLE>