<PAGE>

                                                                   Exhibit 10.11

                       *********************************


                                     Lease


                                 676 St. Clair
                               Chicago, Illinois



                       *********************************


                                    Between

                          Open Port Technology, Inc.
                                   (Tenant)




                                      and




             Teachers Insurance and Annuity Association of America
                                  (Landlord)

<PAGE>

                                     Lease

                                 676 St. Clair
                               Chicago, Illinois

<TABLE>
<CAPTION>
                                                                                                                 Page
<S>                                                                                                              <C>
DEFINITIONS ...................................................................................................   iv

SCHEDULE ......................................................................................................    1

     1.   LEASING AGREEMENT....................................................................................    2
     2.   RENT ................................................................................................    2
          A.   Kinds...........................................................................................    2
          B.   Payment of Operating Cost Share Rent and Tax Share Rent ........................................    2
          C.   Definitions ....................................................................................    4
          D.   Rules of Interpretation and Computation of Base Rent and Rent Adjustments ......................    6
     3.   PREPARATION AND CONDITION OF PREMISES, POSSESSION AND SURRENDER OF PREMISES .........................    8
     4.   PROJECT SERVICES ....................................................................................    9
          A.   Heat and Air Conditioning ......................................................................    9
          B.   Elevators ......................................................................................   10
          C.   Electricity ....................................................................................   10
          D.   Water...........................................................................................   10
          E.   Janitorial Service .............................................................................   11
          F.   Window Washing .................................................................................   11
          G.   Interruption of Service ........................................................................   11
     5.   ALTERATIONS AND REPAIRS .............................................................................   12
     6.   USES OF PREMISES ....................................................................................   13
     7.   BUILDING RULES AND GOVERNMENTAL REGULATIONS .........................................................   13
     8.   CLAIMS; INSURANCE; LIABILITY ........................................................................   13
     9.   FIRE AND OTHER CASUALTY .............................................................................   15
    10.   RIGHTS RESERVED TO THE LANDLORD......................................................................   16
          A.   Name............................................................................................   16
          B.   Signs...........................................................................................   16
          C.   Windows.........................................................................................   16
          D.   Service Contracts...............................................................................   16
          E.   Keys............................................................................................   17
          F.   Access for Repairs, etc.........................................................................   17
          G.   Occupancy.......................................................................................   17
          H.   Rights to Conduct Businesses....................................................................   17
          I.   Heavy Equipment.................................................................................   17
          J.   Show Premises...................................................................................   17
          K.   Close Project...................................................................................   17
          L.   Substitution of Space...........................................................................   18
          M.   Use of Lock Box by Landlord.....................................................................   18
          N.   Repairs and Alterations.........................................................................   19
          O.   Mail Chutes.....................................................................................   19
          P.   Other Rights....................................................................................   19
     11.  DEFAULT AND LANDLORD'S REMEDIES......................................................................   19
          A.   Defaults .......................................................................................   20
          B.   Landlord's Remedies ............................................................................   23
     12.  HOLDOVER ............................................................................................   23
     13.  SUBORDINATION TO MORTGAGES, TRUST DEEDS AND GROUND LEASES ...........................................   23
          A.   Subordination ..................................................................................   23
          B.   Termination of Ground Lease or Foreclosure of Mortgage .........................................   24
</TABLE>

                                      -i-
<PAGE>

<TABLE>
<S>                                                                                                      <C>
          C.   Security Deposit........................................................................   24
          D.   Notice and Right to Cure................................................................   24
     14.  ASSIGNMENT AND SUBLETTING BY TENANT..........................................................   25
     15.  SALE BY LANDLORD.............................................................................   27
     16.  ESTOPPEL CERTIFICATE.........................................................................   27
     17.  SECURITY DEPOSIT.............................................................................   27
     18.  EXCUSE OF LANDLORD'S INABILITY TO PERFORM; LANDLORD'S DEFAULT................................   28
     19.  PERSONAL PROPERTY AND TENANT FIXTURES........................................................   28
     20.  NOTICES......................................................................................   28
     21.  QUIET POSSESSION.............................................................................   29
     22.  REAL ESTATE BROKER...........................................................................   29
     23.  CONDEMNATION.................................................................................   29
     24.  SPRINKLERS...................................................................................   29
     25.  MISCELLANEOUS................................................................................   29
          A.   Covenants Binding on Successors.........................................................   29
          B.   Date Payments Are Due...................................................................   30
          C.   Meaning of "Re-entry" and "Landlord"....................................................   30
          D.   Time Is of the Essence..................................................................   30
          E.   No Option...............................................................................   30
          F.   Severability............................................................................   30
          G.   Governing Laws..........................................................................   30
          H.   Lease Modification......................................................................   30
          I.   No Oral Modification....................................................................   30
          J.   Litigation and Arbitration Costs........................................................   30
          K.   Captions................................................................................   30
          L.   Remedies and Rights May Be Exercised by Landlord In Its Own Name; Authority to
                 Execute This Lease....................................................................   30
          M.   Payments to Affiliates..................................................................   31
          N.   Entire Agreement........................................................................   31
          O.   Landlord's Title........................................................................   31
          P.   Light and Air Rights....................................................................   31
          Q.   No Reservation..........................................................................   31
          R.   Consents................................................................................   31
          S.   Landlord's Agents.......................................................................   31
          T.   Terms "Landlord" and "Tenant"...........................................................   31
          U.   Rent Not Based on Income................................................................   32
          V.   No Recording by Tenant..................................................................   32
          W.   Blue Cross Association, etc.............................................................   32
     26.  UNRELATED BUSINESS INCOME....................................................................   32
     27.  HAZARDOUS MATERIALS..........................................................................   33
     28.  EXCULPATORY PROVISIONS.......................................................................   33
</TABLE>

APPENDIX A - PLAN OF THE PREMISES

APPENDIX B - CLEANING SCHEDULE

APPENDIX C - RULES AND REGULATIONS

APPENDIX D - INTENTIONALLY OMITTED

EXHIBIT A TO APPENDIX D - INTENTIONALLY OMITTED

APPENDIX E - MORTGAGES CURRENTLY AFFECTING THE PROJECT

                                     -ii-
<PAGE>

                                  DEFINITIONS

                                             Section in which
    Term                                      Term is Defined
    ----                                     ----------------
     1. Additional Rent                       2A(5)
     2. Base Rent                             2A(l)
     3. Base Operating Expenses               2A(2)
     4. Base Taxes                            2A(3)
     5. Building                              Preamble
     6. business hours                        4A
     7. Commencement Date                     1
     8. Corporate Base Rate                   2E(3)
     9. CPI Report                            2C(2)
    10. Equitable Adjustment                  2C(2)
    11. Excess Operating Expenses             2A(2)
    12. Excess Taxes                          2A(3)
    13. Fiscal Year                           2D(3)
    14. Force Majeure                         18
    15. Ground Lease                          2D(2)
    16. Holidays                              4A
    17. Land                                  Preamble
    18. Landlord                              Preamble (see also 25C)
    19. mortgage                              13B(3)
    20. mortgagee                             3B(3)
    21. new premises                          10(L)
    22. Operating Cost Share Rent             2A(2)
    23. Operating Costs                       2D(2)
    24. Operating Cost Report                 2B(2)
    25. Premises                              Preamble
    26. Project                               Preamble
    27. re-enter, re-entry                    25C
    28. Rent Tax                              2D(l)
    29. Rental Agents                         2A
    30. Representations                       25N
    31. Required Improvements                 9B
    32. Reconstruction Delays                 9C
    33. Schedule                              Preamble
    34. Taxes                                 2D(1)
    35. Tax Report                            2B(3)
    36. Tax Share Rent                        2A(3)
    37. Tenant                                Preamble
    38. Tenant's Proportionate Share          2(D)(4)
    39. Term                                  1
    40. Termination Date                      1
    41. Work                                  5A

                                     -iii-
<PAGE>

                                     LEASE

                                 676 ST. CLAIR
                               CHICAGO, ILLINOIS

     THIS INDENTURE (this "Lease") is made as of the ___ day of August, 2995
between TEACHERS INSURANCE AND ANNUITY ASSOCIATION OF AMERICA, a New York
Corporation (the "Landlord") and the tenant named in Item 1 of the Schedule (the
"Tenant"). The term "Project" when used herein refers to the land (the "Land")
and the building (the "Building") currently known as "676 ST. CLAIR" (including,
without limitation, any and all easements adjacent thereto) situated at the
northwest corner of St. Clair and Erie Streets, Chicago, Illinois, together with
the vehicular drives and all other structures and improvements now or hereafter
located on the Land. "Premises" when used herein refers to that part of the
Project leased to Tenant.

     The following Schedule (the "Schedule") is an integral part of this Lease.

                                   SCHEDULE

 1.  Name of Tenant: Open Port Technology, Inc., an Illinois corporation
 2.  Floor(s) or room(s) of Premises: the entire 9th floor
 3.  Net Rentable Square Feet: approximately 24,531 square feet
 4.  Tenant's use of Premises: general office subject to Section 6
 5.  Base Rent for the first 12 consecutive calendar months of the term:
     $441,558.00 ($18.00 per rentable square foot for the first Lease Year)
 6.  Monthly Installments of Base Rent for the first 12 consecutive calendar
     months of the term: $36,796.50
 5.  Base Rent for the 13th through the 18th calendar months of the term:
     $225,194.58 ($18.36 per rentable square foot)
 6.  Monthly Installments of Base Rent for the 13th through the 18th calendar
     months of the term: $37,532.43
 7.  Tenant's Proportionate Share: 4.4488% (Tenant's Proportionate Share is
     based on a total of 551,409 rentable square feet in the Building and a
     total of 24,531 rentable square feet in the Premises initially demised
     hereunder.)
 8.  Base Operating Expenses: $3,446,306.25
 9.  Base Taxes: $3,821,264.37
10.  Rent Abatement: N/A
11.  Security Deposit: $36,796.50
12.  Tenant's address for notices before possession date: c/o Stacey Kruger
     Birndorf, Julien Studley, Inc., 1 East Wacker Drive, Suite 3900, Chicago,
     Illinois 60601
13.  Tenant's Real Estate Broker used for this Lease: Julien Studley, Inc.
     (Stacey Kruger Birndorf)
14.  Tenant Improvements, if any: None.
15.  Date Tenant Plans are due from Tenant including special work, if any: N/A
16.  Commencement Date: September 1, 1995 (with a right to occupy on August 19,
     1995, provided this Lease has been fully executed)
17.  Term/Termination Date: Eighteen (18) calendar months after the Commencement
     Date, ending February 28, 1997.

                                     -1-
<PAGE>

           1.  LEASING AGREEMENT.  Landlord leases to Tenant, and Tenant leases
        from Landlord, for the term (the "Term") set forth on the Schedule,
        commencing on the commencement date (the "Commencement Date") set forth
        on the Schedule and ending on the termination date (the "Termination
        Date") set forth on the Schedule, unless sooner terminated or extended
        as herein provided, the Premises described on the Schedule and outlined
        on the plan attached hereto and made a part hereof as Appendix A. The
        Premises constitute a portion of the Building located on the Land. As
        provisions of said Lease, Landlord and Tenant covenant and agree as
        follows:

           2.  RENT.

           A.  Kinds. Tenant agrees to pay rent to Landlord's building manager
               -----
        at the office of the Project located at 676 St. Clair, Chicago, Illinois
        60611 or to such other person or at such other place as Landlord from
        time to time designates in a written notice to Tenant, with Tenant's
        check, or in coin or currency which at the time of payment is legal
        tender for the payment of public and private debts in the United States
        of America, the aggregate of the following, all of which are rent
        reserved under this Lease:

               (1)  Base Rent to be paid in monthly installments in
                    ---------
           advance on or before the first day of each month of the Term of this
           Lease in the amount set forth on the Schedule, provided that the
           first five monthly installments of Base Rent and the Security
           Deposit, totalling $220,779.00, will be paid by the Tenant
           concurrently with the execution of this Lease.

               (2)  Operating Cost Share Rent in an amount equal to the Tenant's
                    -------------------------
           Proportionate Share of the excess (the "Excess Operating Expenses")
           of Operating Costs for the applicable fiscal year of the Lease over
           Operating Costs set forth on the Schedule ("Base Operating
           Expenses"). Operating Cost Share Rent shall be paid monthly in
           advance in an estimated amount, as adjusted by Landlord from time to
           time. Definitions of Operating Costs, Tenant's Proportionate Share
           and the method for billing and payment of Operating Cost Share Rent
           are set forth in Sections 2B and 2D.

               (3)  Tax Share Rent in an amount equal to the Tenant's
                    --------------
           Proportionate Share of the excess (the "Excess Taxes") of Taxes for
           the applicable fiscal year of the Lease over the Taxes set forth on
           the Schedule ("Base Taxes"). Tax Share Rent shall be paid monthly in
           advance in an estimated amount, as adjusted by Landlord from time to
           time. Definitions of Taxes, Tenant's Proportionate Share and the
           method for billing and payment of Tax Share Rent are set forth in
           Sections 2B and 2D.


               (4)    Additional Rent consisting of all of the sums,
                      ---------------
           liabilities, obligations and other amounts (excepting Base Rent,
           Operating Cost Share Rent and Tax Share Rent) which Tenant is
           required to pay or discharge pursuant to this Lease (including,
           without limitation, any amounts which this Lease provides shall be
           Tenant's cost or expense), together with interest for late payment
           thereon, all as hereafter provided.

           B.  Payment of Operating Cost Share Rent and Tax Share Rent.
               ---------------------------------------------------------

                                      -2-
<PAGE>

                (1)  Payment of Estimated Operating Cost Share Rent and Tax
                     -------------------------------------------------------
             Share Rent. Landlord shall estimate the Operating Costs and Taxes
             ----------
             of the Project from time to time each year. Such estimates may be
             revised by Landlord whenever it obtains information relevant to
             making such estimates more accurate. Such estimates will generally
             (but need not) be issued after the beginning of a fiscal year and
             revised upon the determination of the final real estate tax
             assessment or final real estate tax rate for the Project.

                Within thirty (30) days after notice from Landlord setting forth
             (a) an estimate of Operating Costs for a particular fiscal year,
             (b) the Base Operating Expenses and (c) the resulting estimate of
             Excess Operating Costs for such fiscal year, Tenant shall pay
             Landlord an amount equal to one-twelfth (1/12th) of Tenant's
             Proportionate Share of such estimated Excess Operating Costs for
             such fiscal year, multiplied by the number of months that have
             elapsed in such fiscal year to the date of such payment, minus
             payments of estimated Operating Cost Share Rent previously paid for
             said period. Thereafter on the first day of each month, Tenant
             shall pay monthly until a new estimate of Operating Costs is
             applicable, one-twelfth (1/12th) of Tenant's Proportionate Share of
             the estimated Excess Operating Costs.

                Within ten (10) days after notice from Landlord setting forth
             (a) an estimate of Taxes for a particular fiscal year, (b) the Base
             Taxes and (c) the resulting estimate of Excess Taxes, Tenant shall
             pay Landlord an amount equal to one-twelfth (1/12th) of Tenant's
             Proportionate Share of such estimated Excess Taxes, multiplied by
             the number of months that have elapsed in such fiscal year to the
             date of such payment, minus payments of estimated Tax Share Rent
             previously paid for said period. Thereafter on the first day of
             each month, Tenant shall pay monthly until a new estimate of Taxes
             is applicable, one-twelfth (1/12th) of Tenant's Proportionate Share
             of the estimated Excess Taxes.

                (2)  Correction of Operating Cost Share Rent. As soon as
                     ---------------------------------------
             reasonably possible after the end of each fiscal year, Landlord
             shall deliver to Tenant a report (the "Operating Cost Report")
             setting forth (a) the actual Operating Costs for the preceding
             fiscal year, (b) the Base Operating Expenses, (c) the amount of
             Operating Cost Share Rent due to Landlord for such preceding fiscal
             year, and (d) the amount of Operating Expense Share Rent paid by
             the Tenant in and allocable to such fiscal year. On or before
             thirty (30) days after receipt of such report, Tenant shall pay to
             Landlord the amount of Operating Cost Share Rent due for the
             preceding fiscal year (or a portion thereof if this Lease was not
             in effect for the entire fiscal year) minus any payments made by
             Tenant for such fiscal year. If Tenant's estimated payments of
             Operating Cost Share Rent exceed the amount due Landlord for the
             fiscal year in question, Landlord shall apply any such amount as a
             credit against Tenant's other obligations under this Lease, or if
             the Term has expired or this Lease has been terminated and Tenant
             has no further obligations under this Lease (including any
             obligations which survive the expiration or termination of this
             Lease), then Landlord shall refund any such amount to Tenant.

                                      -3-
<PAGE>

                 (3)  Correction of Tax Share Rent. At any time during any
                      ----------------------------
             fiscal year, when such information becomes available, Landlord
             shall deliver to Tenant a report (the "Tax Report") setting forth
             (a) the actual Taxes for the preceding fiscal year, (b) the Base
             Taxes, (c) the amount of Tax Share Rent due to Landlord for such
             preceding fiscal year, and (d) the amount of Tax Share Rent paid by
             the Tenant in and allocable to such fiscal year. On or before
             twenty (20) days after receipt of such report, Tenant shall pay to
             Landlord the amount of Tax Share Rent due for the preceding fiscal
             year (or a portion thereof if this Lease was not in effect for the
             entire fiscal year) minus any payments made by Tenant for such
             fiscal year. If Tenant's estimated payments of Tax Share Rent
             exceed the amount due Landlord for the fiscal year in question,
             Landlord shall apply any such amount as a credit against Tenant's
             other obligations under this Lease, or if the Term has expired or
             this Lease has been terminated and Tenant has no further
             obligations under this Lease (including any obligations which
             survive the expiration or termination of this Lease), then
             Landlord shall refund any such amount to Tenant.

             C.  Definitions:
                 -----------

                 (1) Taxes. "Taxes" shall mean any and all federal, state and
                     -----
             local governmental taxes, assessments and charges of any kind or
             nature, whether general, special, ordinary or extraordinary, which
             Landlord shall pay or become obligated to pay because of or in
             connection with the ownership, leasing, renting, management,
             control or operation of the Project or of the personal property,
             fixtures, machinery, equipment, systems and apparatus located
             therein or used in connection therewith. Taxes shall include,
             without limitation, real estate taxes, personal property taxes,
             sewer rents, water rents, assessments (special or otherwise),
             transit taxes, ad valorem taxes and the Illinois Replacement Tax.
             Taxes shall also include all fees, costs and expenses (including,
             without limitation, legal fees and court costs) paid by Landlord in
             connection with protesting or contesting, or seeking a refund or
             reduction of, any of the aforesaid Taxes, regardless of whether the
             Landlord is ultimately successful. If at any time during the term
             hereof, a tax or excise on rents or income or other tax however
             described (the "Rent Tax") is levied or assessed by the United
             States or the State of Illinois, or any political subdivision
             thereof, on account of the rents hereunder or the interest of
             Landlord under this Lease, such Rent Tax shall constitute and be
             included in Taxes, provided, however, that in no event shall Tenant
             be obligated (a) to pay for any year any greater amount as a result
             of such Rent Tax than would have been payable by Tenant had the
             rentals paid to Landlord under all Project leases (being the
             rentals upon which such taxes are imposed) been the sole taxable
             income of Landlord for the year in question or (b) to pay or to
             reimburse Landlord for any tax of any kind assessed against
             Landlord on account of any such Rent Tax having been reimbursed to
             Landlord by Tenant or any third party.

                 For the purpose of determining Taxes for any given fiscal year,
             the amount to be included for such fiscal year (a) from special
             taxes or assessments payable in installments, shall be the amount
             of the installments (and any interest) due and payable during such
             fiscal year, (b) from all other Taxes,

                                      -4-
<PAGE>

             shall be the amount accrued, assessed or otherwise imposed for such
             fiscal year without regard to when any such Taxes are payable, and
             (c) from any adjustment (including, without limitation, a refund)
             to any Taxes by the taxing authority, when such adjustment has
             resulted in a corresponding adjustment payment by or to Landlord,
             shall constitute an adjustment to Taxes for the fiscal year during
             which such adjustment is made or received by Landlord, as the case
             may be.

                 Taxes shall not include any net income (except Rent Tax as
             hereinabove provided), capital, stock, succession, transfer,
             franchise, gift, estate or inheritance taxes, unless the same
             shall be imposed in lieu of all or any portion of Taxes.

                 (2)  Operating Costs. "Operating Costs" shall mean any
                      ---------------
             expenses, costs and disbursements (other than Taxes) of every kind
             and nature, paid or incurred by Landlord in connection with the
             ownership, leasing, management, maintenance, operation and repair
             of all or any part of the Project (adjusted for vacancy as
             hereafter provided) and of the personal property, fixtures,
             machinery, equipment, systems and apparatus located in the Project
             or used in connection therewith. Operating Costs shall not include
             (a) costs of alterations of tenant premises; (b) costs of capital
             improvements, except for any capital improvements which are
             intended to reduce Operating Costs, and any capital improvements
             which Landlord is required to make pursuant to, or which Landlord
             shall deem necessary to keep the Project in compliance with, all
             applicable governmental rules and regulations applicable from time
             to time to the Project (the foregoing capital improvements that are
             included within Operating Costs are collectively referred to herein
             as the "Included Capital Items"), provided that the cost of such
             Included Capital Items shall be evenly amortized by Landlord over
             the useful life of such Included Capital Item and such amortized
             costs are only included in Operating Costs under this Lease for
             that portion of the useful life of the Included Capital Item which
             falls within the Term; (c) depreciation (except on any Included
             Capital Items); (d) interest and principal payments on mortgages or
             any rental payments on any ground or other underlying leases
             subject to which Landlord holds its interest in the Project
             (hereinafter, referred to individually as a "Ground Lease" and
             collectively as "Ground Leases"), and other debt costs, if any; (e)
             real estate brokers' leasing commissions or compensations; (f) any
             cost or expenditure (or portion thereof) for which Landlord is
             reimbursed, whether by insurance proceeds or otherwise (Operating
             Cost Share Rent and Tax Share Rent provided for in any tenant
             leases are not reimbursements); (g) the cost of any kind of
             service furnished to any other office tenant of the Project which
             Landlord does not make available to Tenant hereunder; (h)
             executives' salaries above the grade of building manager; (i) legal
             and auditing fees which are for the benefit of Landlord such as
             collecting delinquent rents and enforcing tenant leases, preparing
             partnership returns and other partnership financial statements, and
             audits other than those incurred in connection with the preparation
             of statements required pursuant to Section 2B above; and (j) legal
             fees, space planner fees, real estate brokers'

                                      -5-

<PAGE>

             leasing commissions and advertising expenses incurred with regard
             to leasing the Building or portions thereof.

                 If during all or any portion of any fiscal year the Project is
             not fully rented and occupied by tenants, Landlord may elect to
             make an appropriate adjustment (an "Equitable Adjustment") of
             Operating Costs for such fiscal year, employing sound accounting
             and management principles, to determine the Operating Costs that
             would have been paid or incurred by Landlord had the Project been
             fully rented and occupied for the entire fiscal year, and the
             amount so determined shall be deemed to have been the Operating
             Costs for such fiscal year. The foregoing process illustrated by
             the following hypothetical which assumes (i) the Building has ten
             floors; (ii) the Tenant occupies one floor and therefor, Tenant's
             Proportionate Share is ten percent (10%); (iii) the other nine
             floors are vacant; (iv) the cost of providing a particular service
             for Tenant's floor is $1,000. If Tenant were to pay Tenant's
             Proportionate Share of the cost of such service for the Building it
             would pay $100. Instead, Landlord shall estimate the cost of such
             service for the Building if it were one hundred percent (100%)
             occupied. If there would be any savings in the variable costs per
             floor of providing the service because such service would be
             provided for all ten floors, instead of one floor, these should be
             taken into account by Landlord in making its estimate. If some
             savings would exist, the estimate of the Landlord would be an
             amount that is less than the amount obtained by multiplying the
             number of floors in the Building by the cost of providing such
             service to one floor (10 x $1000); for example, $9,000. The amount
             of Landlord's estimate ($9,000) less the actual cost incurred by
             the Landlord in providing the service ($1000) would equal the
             Equitable Adjustment ($8000). The Equitable Adjustment would be
             added to the accrual cost and Tenant would then pay Tenant's
             Prorata Share of this amount, that is, Tenant would pay $9,000
             times 10%, which equals $900.

                 If Landlord is not furnishing any particular work or service
             (the cost of which if performed by Landlord would constitute an
             Operating Cost) to a tenant who has undertaken to perform such work
             or service in lieu of the performance thereof by Landlord for all
             or any portion of a fiscal year, Operating Costs for such fiscal
             year shall be deemed to be increased by an amount equal to the
             additional Operating Costs which reasonably would have been
             incurred during such fiscal year by Landlord if it had, at its own
             expense, furnished such work or service to such tenant.

                 Notwithstanding anything contained herein to the contrary, the
             provisions of this Section 2C(2) with respect to an Equitable
             Adjustment of Operating Costs for vacancy, or as a result of the
             performance by tenants of certain services, shall apply only to
             Operating Costs which are variable and which increase as occupancy
             in the Project increases and shall not apply to any Operating Costs
             which do not vary with the amount of occupancy in the Project.

                 (3)  Fiscal Year. The term "fiscal year" shall mean any 12
                      -----------
             month period (including, without limitation, the calendar year)
             which Landlord may from time to time select as the fiscal year of
             the Project, provided that the first fiscal

                                      -6-
<PAGE>

     year and the last fiscal year of the Term may contain less than twelve (12)
     months.

          (4)  Tenant's Proportionate Share. "Tenant's Proportionate Share"
               ----------------------------
     shall mean the percentage set forth as Item 7 on the Schedule.

     D.   Rules of Interpretation and Computation of Base Rent and Rent
          -------------------------------------------------------------
Adjustments:
-----------

          (1)  If this Lease commences on other than the first day of a month,
     the Base Rent, Operating Cost Share Rent and Tax Share Rent for the month
     in which this Lease so begins shall be prorated based upon the number of
     days of the Term falling within such month. If the Term of this Lease
     commences on any day other than the first day of the designated fiscal
     year, or if the Term of this Lease ends on any day other than the last day
     of the designated fiscal year, any Operating Cost Share Rent and Tax Share
     Rent due to Landlord with respect to such fiscal year shall be prorated
     based on the number of days in the Term falling within such fiscal year.

          (2)  All rent shall be paid to Landlord without deduction or offset at
     the office of the building manager in the Project, or to such other person
     or place as Landlord may from time to time designate in writing. The
     Tenant's covenants to pay rent shall be independent of every other covenant
     set forth in this Lease.

          (3)  Any sum due from Tenant to Landlord not paid when due shall bear
     interest from the date due until the date paid at the annual rate equal to
     the lesser of: (i) the highest lawful rate, or (ii) a rate of interest
     equal to the sum of three percent (3%) plus the "Corporate Base Rate" at
     the time of such default. The phrase "Corporate Base Rate" means that rate
     of interest most recently announced by the First National Bank of Chicago,
     or its successor (collectively, the "First") as the corporate base rate,
     changing automatically and simultaneously with each announced change by the
     First in the Corporate Base Rate, such change to be effective as of and on
     the date announced by the First as the effective date for the change in the
     Corporate Base Rate. A certificate made by an officer of the First
     stating the Corporate Base Rate in effect on a certain day, or Corporate
     Base Rates in effect during a certain period, shall, for purposes of this
     Lease, be conclusive evidence of the First's Corporate Base Rate or Rates
     on said day or during such period. In the event that the First ceases to
     use the term Corporate Base Rate in setting a base rate of interest for
     commercial loans, then the Corporate Base Rate herein shall be determined
     by reference to the rate used by the First as a base rate of interest for
     commercial loans as the same shall be designated by the First to the
     Landlord. The payment of such interest shall not excuse or cure any default
     of Tenant under this Lease.

          (4)  If Tenant is in default of any of its obligations under this
     Lease, Tenant shall not be entitled to any refund of any sum which may
     otherwise be due it by application of any provision of this Lease until any
     and all of Tenant's defaults under this Lease are cured by Tenant.

                                      -7-
<PAGE>

          (5)  If changes are made to this Lease or to the Project changing the
     number of rentable square feet contained in the Premises or in the Project,
     Tenant's Proportionate Share shall be appropriately adjusted and the
     computations of rent shall be appropriately adjusted so as to take into
     account the different Tenant's Proportionate Share figures applicable
     during each portion of the applicable fiscal year.

          (6)  Landlord shall maintain books and records in accordance with
     sound accounting and management practices, reflecting the Operating Costs
     and Taxes. In the event of any dispute as to any Operating Cost Share Rent
     or Tax Share Rent, Tenant shall have the right to inspect Landlord's
     accounting records relative to Operating Costs and Taxes at Landlord's
     accounting office upon reasonable prior notice during normal business hours
     during the forty-five (45) days following the furnishing by Landlord to
     Tenant of either of the Operating Cost Report and the Tax Report. Unless
     Tenant shall take written exception to any item in any such report within
     said forty-five (45) day period, such report shall be considered as final
     and accepted by Tenant. Any payment due to the Landlord as shown on the
     Operating Cost Report or the Tax Report, whether or not written exception
     is taken thereto, shall be made by the Tenant within thirty (30) days after
     the Landlord shall have submitted the Operating Cost Report or the Tax
     Report (as the case may be) without prejudice to any such written
     exception. If Tenant makes such timely written exception, a certification
     as to the proper amount of Operating Cost Share Rent and Tax Share Rent
     shall be made by Landlord's independent certified public accountant, which
     shall be final and conclusive. Tenant agrees to pay the cost of such
     certification unless it is determined that Landlord's original
     determination of the aggregate of Taxes and Operating Costs was in error by
     more than five percent (5%) of said amounts.

          (7)  In the event of the termination of this Lease by expiration of
     the stated Term or for any other cause or reason whatsoever prior to the
     determination of Operating Cost Share Rent, Tax Share Rent or Additional
     Rent, Tenant's agreement to pay any such sum shall survive termination of
     the Lease and Tenant shall pay any such amount due to Landlord within
     thirty (30) days after being billed therefor. Tenant's obligation to pay
     Base Rent shall also survive the expiration or termination of this Lease.
     In the event of the termination of this Lease by expiration of the stated
     Term or for any other cause or reason whatsoever, except the default by
     Tenant under any of the terms or provisions of this Lease, prior to the
     determination of Operating Cost Share Rent or Tax Share Rent as hereinabove
     set forth, Landlord's agreement to refund any excess in the amount of the
     estimated payments made by Tenant on account of Operating Cost Share Rent
     or Tax Share Rent over the actual amount thereof accruing or payable up to
     the time of the termination or expiration shall survive termination of the
     Lease and Landlord shall pay the amount due to Tenant within fifteen (15)
     days of Landlord's determination of such amount.

          (8)  No calculation, determination or payment of Operating Cost Share
     Rent or Tax Share Rent, by virtue of the operation of the rent adjustment
     provisions under this Section

                                      -8-
<PAGE>

     2 shall result in the payment by Tenant in any fiscal year during the Term
     of less than the Base Rent shown on the Schedule.

          (9)  If any Operating Cost though paid in one fiscal year, relates to
     more than one fiscal year, at the option of the Landlord, such Operating
     Cost may be proportionately allocated among such related fiscal years. If
     any Operating Cost relates to more than one parcel of property, at the
     option of the Landlord, such Operating Cost may be proportionately
     allocated among all parcels of property to which it relates.

          (10) All payments made with respect to Operating Cost Share Rent or
     Tax Share Rent (including any monthly payments made on the basis of
     Landlord's estimates thereof) may be commingled and need not be segregated
     by the Landlord and may be held and utilized by the Landlord without
     payment to the Tenant of interest or any sums for the use of any of said
     amounts.

     3.   PREPARATION AND CONDITION OF PREMISES, POSSESSION AND
          SURRENDER OF PREMISES.

     A.   Landlord is leasing the Premises to Tenant "as is", without any
representations or warranties of any kind (including, without limitation, any
express or implied warranties of merchantability, fitness or habitability) and
without any obligation on the part of the Landlord to alter, remodel, improve,
repair, decorate or clean the Premises or any part thereof.

     B.   During the term of this Lease, Tenant shall maintain the Premises in
as good condition as when Tenant took possession, or as when completed after
possession in the event that Tenant takes possession prior to the Commencement
Date (loss or damage caused by action of the elements, Acts of God and the
public enemy, ordinary wear and fire and other casualty insured against by
Landlord excepted), failing which Landlord may but need not restore the Premises
to such good condition and Tenant shall pay the cost thereof. At the termination
of this Lease or at the termination of Tenant's right to possession without
termination of this Lease, Tenant shall, subject to Sections 3C and 3D below,
return the Premises to Landlord broom clean and in good condition as described
in the immediately preceding sentence or Landlord may, but need not, restore the
Premises to such good condition (except that Tenant shall be under no obligation
to restore the partitions which are to be torn down by Tenant pursuant to those
certain demolition and construction plans of the Environment Group dated August
16, 1995) and Tenant shall pay the cost thereof.

     C.   Unless otherwise provided by written agreement, signed by Landlord,
all Work (hereinafter defined), partitions, hardware, light fixtures and other
fixtures (except trade fixtures and movable furniture and equipment belonging to
Tenant) in or upon the Premises, whether placed there by Landlord or Tenant,
shall be surrendered with the Premises at the termination of this Lease, by
lapse of time or otherwise, or at the termination of Tenant's right to
possession without termination of this Lease, and shall become Landlord's
property without compensation to Tenant; provided, however, that if prior to any
such termination of the Lease, or of the right to possession, or within ten (10)
days thereafter,

                                      -9-

<PAGE>

Landlord so directs by written notice, Tenant shall promptly remove any work,
partitions, hardware, light fixtures or other fixtures placed in or upon the
Premises by Tenant and designated in such notice and repair any damage to the
Premises caused by such removal, failing which Landlord may remove the same and
repair the Premises and Tenant shall pay the cost thereof to Landlord upon
demand.

     D.   Tenant shall also remove its furniture, movable equipment, trade
fixtures and all other items of personal property from the Premises prior to the
end of the Term or any extension thereof, or within thirty (30) days after the
early termination of this Lease for any reason, or of the termination of
Tenant's right of possession; and if Tenant does not remove such property, at
Landlord's election: (i) Tenant shall be conclusively presumed to have conveyed
the same to Landlord under this Lease as a bill of sale without further payment
or credit by Landlord to Tenant, (ii) Tenant shall be conclusively presumed to
have forever abandoned such property, and without accepting title thereto,
Landlord may, at Tenant's expense, remove, store, destroy, discard or otherwise
dispose of all or any part thereof in any manner that Landlord shall choose
without incurring liability to Tenant or to any other person, and Tenant shall
pay to Landlord, upon demand, any and all reasonable expenses incurred in taking
any of such actions. In no event shall Landlord ever become or accept or be
charged with the duties of a bailee (either voluntary or involuntary) of any
personal property; and the failure of Tenant to remove all such property from
the Premises and the Project shall forever bar Tenant from bringing any action
or asserting any liability against Landlord with respect to any such property
which Tenant fails to remove.

     E.   All obligations of the Tenant hereunder shall survive the expiration
of the Term or sooner termination of this Lease.

     F.   Tenant's taking possession of the Premises or any portion thereof
shall be conclusive evidence that the Premises or such portion were then in good
order, repair and satisfactory condition. Landlord may authorize Tenant to take
possession of all or any part of the Premises prior to the Commencement Date. If
Tenant does take possession pursuant to such authorization, all of the covenants
and conditions of this Lease shall apply to and shall control such pre-term
occupancy except that Tenant shall not be obligated to pay Base Rent, Operating
Cost Share Rent or Tax Share Rent.

     4.   PROJECT SERVICES.

     So long as Tenant is not in default hereunder, Landlord agrees to furnish
services to the Tenant without charge except for Operating Cost Share Rent,
electricity and as otherwise specifically provided herein, as follows:

     A.   Heat and Air Conditioning. Landlord shall furnish air conditioning
          -------------------------
such that the average temperature condition of the Premises is 76(degrees)F +
2(degrees)F dry bulb with 50% + 5% relative humidity when the outdoor conditions
are not above 91(degrees)F dry bulb, and Landlord shall furnish heat such that
the average temperature condition of the Premises is 67(degrees)F+2(degrees) dry
bulb when the outdoor conditions are not below 5(degrees)F dry bulb. Such heat
and air conditioning shall be provided daily during business hours (8:00 a.m. to
6:00 p.m. Monday through Friday and 8:00 a.m. to 1:00 p.m. Saturday), Sundays
and Holidays (hereinafter defined) excepted. Tenant agrees to keep and

                                     -10-
<PAGE>

cause to be kept closed all windows in the Premises and at all times to
cooperate fully with the Landlord in the operation of the heating and air
conditioning systems and to abide by all reasonable regulations and requirements
which Landlord may prescribe to permit the proper functioning and protection of
the heating and air conditioning systems. Landlord reserves the right to stop
the heating and air conditioning systems when necessary by reason of accident or
emergency or for repairs, alterations, replacements or improvements, which in
the judgment of the Landlord are desirable or necessary, until said repairs,
alterations, replacements or improvements shall have been completed; provided,
however, that Landlord shall cause as little inconvenience or annoyance to
Tenant as is reasonably possible under the circumstances. For purposes of this
Lease "Holidays" shall mean any Legal Holiday as defined in Illinois Compiled
Statutes, Chapter 205, Paragraph 630/17 (formerly I11. Rev. Stat. 1985, Ch. 17,
pars. 2201, 2202), as amended from time to time. Landlord agrees to make any
repairs to the heating and air conditioning systems promptly and with due
diligence.

     Whenever heavy concentration of personnel, motors, machines or equipment,
including telephone equipment, used in the Premises adversely affects the
temperature otherwise maintained by the air conditioning system, Landlord
reserves the right to install supplementary air conditioning units in the
Premises and the cost thereof, including all of the costs relating to the
installation and the cost of operation and maintenance thereof, shall be
Additional Rent hereunder and shall be paid by Tenant to Landlord upon demand.

     Landlord shall also furnish heat and air conditioning after business hours,
on the condition that Tenant gives Landlord not less than twenty-four (24)
hours' prior notice of Tenant's needs for such additional heating or air
conditioning, and provided that Tenant pays to Landlord its then current charges
for such additional heating or air conditioning. Such charges will be prorated
by Landlord between requesting user-tenants if more than one tenant requests
such additional heating or air conditioning at the same time and the proration
shall be based on the area of the Project leased to such tenants and their
respective periods of use.

     B.   Elevators. Landlord shall provide passenger elevator service in common
          ---------
with the Landlord and the other tenants, daily, during business hours, Sundays
and Holidays excepted. Tenant may request additional freight elevator service
provided that such service shall be at Tenant's sole cost and expense. Freight
elevator service shall at all times be subject to scheduling by the Landlord.
Landlord shall provide limited passenger elevator service at all times (except
in the case of an emergency) during which normal passenger elevator service is
not furnished.

     C.   Electricity. All the electricity used in the Premises shall be
          -----------
supplied by Commonwealth Edison Company or any other electricity company
serving the Project, and such electricity shall be supplied through a separate
meter and be paid for by Tenant, provided that Landlord shall pay for the
electricity required for the operation of the Building's shared heating,
ventilating and air conditioning systems at the times specified in Section 4A
above. The meter shall be installed at the expense of Tenant or the electricity
company. Landlord shall not in any way be liable to Tenant for any loss or
damage or expense Tenant may sustain or incur if either the amount or quality of
electric service is changed or is no longer available or suitable for Tenant's
requirements. Subject

                                     -11-
<PAGE>

to Section 4G, if such service shall be discontinued, such discontinuance shall
not in any way affect this Lease. Tenant covenants and agrees that at all times
its use of electric current shall never exceed the capacity of the existing
feeders to the Building or the risers or the wiring installed thereon when
reviewed in conjunction with the electrical usage of the other tenants in the
Project. Tenant covenants and agrees that it shall make no alterations or
additions to the electric equipment and/or appliances without the prior written
consent of Landlord in each instance. Landlord shall maintain the light fixtures
in the Premises and install any lamps, bulbs, ballasts or starters to be used by
Tenant in the Premises, all at Tenant's sole cost and expense.

     Tenant shall pay for all electricity required during janitorial service and
alterations and repairs to the Premises and Tenant shall pay for all electricity
required for the operation of any special air conditioning or ventilating system
for its office machinery or equipment requiring special or extra current.

     D.   Water. Landlord shall furnish cold water from City of Chicago mains
          -----
from regular Building outlets for drinking, lavatory and toilet purposes, drawn
through fixtures installed by Landlord or by Tenant with Landlord's prior
written consent, and hot water for public lavatory purposes from the regular
supply of the Building. Tenant shall pay Landlord at Landlord's actual cost for
water furnished for any other purpose as Additional Rent hereunder. Tenant shall
not waste or permit the waste of water.

     E.   Janitorial Service. Landlord shall also furnish janitorial and
          ------------------
cleaning services as set forth in Appendix B, on Monday through Friday, Holidays
excepted. Tenant shall not provide janitorial services in the Premises without
the prior written consent of Landlord and then only at Tenant's sole
responsibility, cost and expense, by contractors or employees at all times
satisfactory to Landlord in its sole discretion.

     F.   Window Washing. Landlord shall furnish window washing of all exterior
          --------------
windows, weather permitting, at intervals to be determined by Landlord, but not
less than three times during each calendar year.

     G.   Interruption of Service. Landlord does not warrant that any service
          -----------------------
will be free from interruption caused by labor controversies, accidents,
inability to obtain fuel, steam, water or supplies, governmental regulations, or
other causes beyond the reasonable control of the Landlord, or repairs,
alterations, replacements or improvements to such systems. No such interruption
of Service shall be deemed an eviction or disturbance of Tenant's use and
possession of the Premises or any part thereof, or render Landlord liable to
Tenant for damages, by abatement of rent or otherwise, or relieve Tenant from
performance of Tenant's obligations under this Lease, except as provided below.

     The rent otherwise payable under this Lease shall abate in the manner
described in the last sentence of this paragraph if all of the following
conditions are met: (i) if Landlord ceases to furnish any service in the
Building as a result of a condition which affects only the Building (i.e. which
does not affect office buildings in general in the vicinity of the Building);
and (ii) if Tenant notifies Landlord in writing within one (1) business day
after such cessation; and (iii) if such cessation is not caused by Force

                                     -12-
<PAGE>

Majeure (as defined in Section 18 of this Lease); and (iv) if such cessation has
not arisen as a result of an act or omission of Tenant; and (v) as a result of
such cessation, the Premises (or a material portion thereof) is rendered
untenantable (meaning that Tenant is unable to use such space in the normal
course of its business) and Tenant in fact so ceases to use such space in the
manner used prior to such cessation. As Tenant's sole and exclusive remedy for
such cessation, on the sixth day after all of the foregoing conditions have been
met, the rent payable hereunder shall be equitably abated based upon the
percentage of the space in the Premises so rendered untenantable and not being
so used by Tenant, and such abatement shall continue until the date the Premises
become tenantable again.

     Tenant shall make arrangements directly with the telephone company
servicing the Building for such telephone service in the Premises as may be
desired by Tenant. Tenant shall pay the entire cost of all telephone charges,
electricity consumed within the Premises, maintenance of light fixtures and
replacement of lamps, bulbs, tubes, ballasts and starters.

     5.   ALTERATIONS AND REPAIRS.

     A.   Tenant shall not make any improvements or alterations in or additions,
changes or installations to the Premises which (i) impact the base structural
components or the heating, air conditioning, ventilation, electrical, plumbing
or mechanical systems (collectively, the "Systems") of the Building or (ii)
impact any other tenant's premises (collectively, the "Systems/Structure Work"),
without submitting plans and specifications therefor to Landlord, and obtaining
Landlord's prior written consent thereto (which consent Landlord may withhold in
its sole discretion). Tenant shall not make any improvements or alterations in
or additions, changes or installations to the Premises which are not deemed
Systems/Structure Work pursuant to this Section 5A, without submitting plans and
specifications therefor to Landlord, and obtaining Landlord's prior written
consent thereto (which consent shall not be unreasonably withheld), if (a) the
cost thereof is in excess of $5,000.00, or (b) such improvements, alterations,
additions, changes or installations are visible from outside the Premises
(collectively, the "Non-Systems Work"). Tenant shall be allowed to make any
improvements or alterations in or additions, changes or installations to the
Premises which are not deemed Systems/Structure Work or Non-Systems Work
pursuant to this Section 5A without Landlord's consent (collectively, the "Non-
Consent Work"), but Tenant shall be obligated to notify Landlord of the nature
and scope of such work and otherwise comply with the provisions of this Section
5, failing which Landlord may deny Tenant's contractors access to the Premises.
For purposes of this Lease, Systems/Structure Work, Non-Systems Work and Non-
Consent Work are sometimes collectively referred to herein as the "Work".
Landlord hereby agrees to inform Tenant of its approval or disapproval of any
such Systems/Structure Work or Non-Systems Work within fifteen (15) days after
receipt of a complete set of plans and specifications therefor. All Work shall
be performed (a) at the sole cost and expense of Tenant by employees of or
contractors employed by Landlord, or with Landlord's written consent given prior
to the letting of the contract, by contractors employed by Tenant under a
written contract previously approved in writing by Landlord, and (b) on such
terms and under such conditions as Landlord, in its sole discretion, shall
determine as will protect the Premises, the

                                     -13-
<PAGE>

Building and the Project from improper contractors' work and against the
imposition of any lien resulting from Work; without limiting the foregoing, if
Landlord consents to any Work, it shall be performed subject to the following
requirements:

          (1)  If the Work is to be done by Tenant's contractors, Tenant shall
     furnish to Landlord prior to commencement thereof, building permits and
     certificates of appropriate insurance and bonds satisfactory in all
     respects to Landlord. Tenant shall also furnish to Landlord, if Landlord so
     requests, security for the payment of all costs to be incurred in
     connection with the Work.

          (2)  Upon completion of any Work, Tenant shall furnish Landlord with
     contractors' affidavits and full and final waivers of lien, each conforming
     to the applicable Illinois statutory requirements, as-built plans of any
     Work and receipted bills covering all labor and materials expended and
     used. Insofar as applicable to the work or material for which payment is
     requested or notice or lien claim is made, Landlord in its sole discretion
     shall make available for partial or final payment or release thereof such
     funds as may have been deposited with it by Tenant for the estimated cost
     of such Work.

          (3)  Any Work permitted to be undertaken by Tenant's contractors shall
     be performed in such a fashion and by such means as necessary to maintain
     peace and harmony among the other contractors serving the Project and the
     other tenants and so as not to cause interference with the continuance of
     work to be performed or services to be rendered to the Project or the other
     tenants.

          (4)  All Work shall comply with all insurance requirements and with
     all applicable laws, ordinances and regulations. All Work shall be
     constructed in a good and workmanlike manner, and only good grades
     of material shall be used with a quality equal to or better than that used
     in the Project.

          (5)  Tenant shall permit Landlord to supervise all Work within the
     Premises. Except for the Work set forth on the construction bid attached
     hereto as Appendix F for which no supervisory fee will be charged, Landlord
     shall charge a supervisory fee not to exceed (a) ten percent (10%) of the
     total cost of the Work, including, without limitation, all labor and
     material costs, if Landlord's employees or contractors perform the Work,
     and (b) five percent (5%) of the total cost of the Work, including, without
     limitation, all labor and material costs, if Tenant's employees or
     contractors perform the Work.

     B.   If Tenant desires telegraphic, telephonic, burglar alarm, computer
installations or signal service (all of which shall be at Tenant's sole cost and
expense), Landlord shall, upon request, direct where and how all connections and
wiring for such service shall be introduced and run. In the absence of any such
directions, Tenant shall make no borings, cutting or install any wires or cable
in or about the Premises.

                                   -14-
<PAGE>

     C.   Tenant agrees to protect, defend and indemnify Landlord, its agents
(including, without limitation, the building manager) and employees, the
Premises, the Building and the Project from and against any and all liabilities
of every kind and description which may arise out of or be connected in any way
with any Work, whether performed by or under the direction of Landlord and at
the cost of Tenant or performed by Tenant and whether performed in compliance
with this Section 5.

     D.   Any mechanic's lien filed against the Premises or the Project or any
notice which is received by either Landlord or Tenant or filed for work or
materials furnished or claimed to be furnished and deriving from Work or for
materials or work claimed to have been furnished to Tenant or the Premises shall
be released and discharged of record by Tenant, in either case, within thirty
(30) days after such filing or receipt, whichever is applicable, at Tenant's
expense. If Tenant chooses to contest such claim, notice or lien, Tenant may do
so in place of causing the release and discharge thereof, provided that within
said thirty (30) day period, (i) Tenant provides Landlord with a title indemnity
or bond or other adequate security covering any possible lien or claim that may
arise from the failure to release and discharge such claim, notice or lien; (ii)
Tenant contests such claim, notice or lien in good faith by appropriate
proceedings that operate to stay enforcement thereof; and (iii) Tenant promptly
pays and discharges any final adverse judgment entered in any such proceeding.
If Tenant has not caused the release or discharge or begun appropriate
proceedings to contest such claim, notice or lien, within said thirty (30) days,
Landlord may, but shall not be obligated to, pay the amount necessary to remove
the same without being responsible for making an investigation as to the
validity or accuracy thereof, and the amount so paid, together with all costs
and expenses (including, without limitation, reasonable attorneys' fees)
incurred by Landlord in connection therewith, shall be deemed Additional Rent
hereunder, payable upon demand. Tenant has no power or authority to cause or
permit any lien or encumbrance of any kind whatsoever, whether created by act of
Tenant, operation of law or otherwise, to attach to or be placed upon Landlord's
title or interest in the Premises or the Project, and any and all liens and
encumbrances created by Tenant shall attach to Tenant's interest only.

     E.   Except for ordinary wear and as otherwise provided in this Lease,
Tenant shall, at all times during the Term hereof, at its sole expense, keep all
Tenant's movable and removable fixtures located in or appurtenant to the
Premises in good order, repair and condition, and Tenant shall promptly arrange
with the Landlord to have Landlord (or Landlord's agent) make repairs of all
other damages to the Premises and the replacement or repair of all damaged or
broken glass (including signs thereon), fixtures and appurtenances (including
hardware and heating, cooling, ventilating, electrical, plumbing and other
mechanical facilities in the Premises), with materials equal in quality and
class to the original materials damaged or broken, within any reasonable period
of time specified by Landlord. Landlord may, but shall not be required to do so,
enter the Premises at all reasonable times to make any repairs, alterations,
improvements or additions, as Landlord shall desire or deem necessary for the
safety, protection, preservation or improvement of the Project, or as Landlord
may be required to do by any governmental department or agency, or by the order
or decree of any court or by any other proper authority; provided, however, that
Landlord shall cause as little inconvenience or annoyance to Tenant

                                     -15-
<PAGE>

as is reasonably possible under the circumstances. The cost of all repairs made
by Landlord to the Project which are made necessary as a result of misuse or
neglect by Tenant or Tenant's employees, invitees, servants, contractors or
agents shall be immediately paid as Additional Rent by Tenant to Landlord within
thirty (30) days of being billed for same. The cost of all other repairs and
replacements (except those caused by Tenant's misuse or negligence and those
relating to Tenant's movable and removable fixtures) shall be paid for by the
Landlord and deemed an item of Operating Costs.

     6.   USES OF PREMISES. The Premises shall be occupied and used by Tenant
only for general office purposes, and for no other purpose; except that if the
zoning classification of the Building so permits (and Tenant hereby acknowledges
that Landlord makes no representation or warranty in this regard) and subject to
the requirements of applicable zoning laws and ordinances, Tenant may also
perform light assembly of computers and computer peripherals. Without limiting
the generality of the foregoing, no use shall be made of the Premises nor acts
done which will increase the existing rate of insurance upon the Project or
cause a cancellation of any insurance policy covering the Project or any part
thereof or require additional insurance coverage. Tenant shall not permit to be
kept, used or sold in or about the Premises any article which may be prohibited
by Landlord's insurance policies.

     7.   BUILDING RULES AND GOVERNMENTAL REGULATIONS. Tenant shall abide by all
applicable laws or governmental regulations concerning its use of the Premises.
Tenant shall also abide by all uniform reasonable rules and regulations adopted
or to be adopted from time to time by Landlord pertaining to the operation and
management of the Project. If any rules and regulations are contrary to the
terms of the Lease, the terms of this Lease shall prevail. The present rules are
contained in Appendix C. The violation of the Project rules or the laws or
regulations governing Tenant's use of the Premises shall be a default under this
Lease allowing Landlord all remedies for default set forth under Section 11 of
this Lease. Landlord shall not be responsible to Tenant for violation of rules
or regulations or terms of this Lease or any other Lease in the Project by
another tenant, nor shall failure to obey the same by others or lack of
enforcement by Landlord relieve Tenant from its obligations to comply therewith.

    8.    CLAIMS; INSURANCE; LIABILITY.

     A.   To the extent permitted by law, Tenant waives all claims it may have
against Landlord, its officers, directors, servants, agents or employees for
damage to person or property sustained by Tenant or by any occupant of the
Premises or the Project, or any other person, occurring in or about the Premises
or the Project, resulting from the Premises or the Project or any part of said
Premises or Project becoming out of repair or resulting from any existing or
future condition, defect, matter or thing in the Premises, the Project or any
part of it, or from equipment or appurtenances therein, or from the action of
the elements, or any accident within or adjacent to the Premises or Project or
resulting directly or indirectly from any act or omission of Landlord or any
occupant of the Premises or Project or any other person while on the Premises or
the Project. If any such damage to the Premises or the Project or any equipment
or appurtenances therein, or to tenants thereof, or their agents, employees,
contractors or invitees, results from any act, omission or negligence of Tenant,
its agents,

                                     -16-
<PAGE>

employees, servants, contractors or invitees, Landlord may, at Landlord's
option, repair such damage and Tenant shall reimburse Landlord within thirty
(30) days of invoice for all costs of such repairs and damages. All property on
the Project or in the Premises belonging to the Tenant, its agents, employees,
servants, contractors or invitees or to any occupant of the Premises shall be
there at the risk of the Tenant or such other person only and Landlord shall not
be liable for damage thereto or theft, misappropriation or loss thereof.
Notwithstanding anything contained in this Section 8 to the contrary, no
agreement of Tenant in this Section 8 shall be deemed to exempt Landlord from
liability for injury to persons or damage to property caused by or resulting
from the negligence of Landlord, its agents or employees in the operation or
maintenance of the Premises or the Project.

     B.   Landlord and Tenant agree to have all property insurance policies
which may be carried by either of them endorsed with a clause providing that any
release from liability of or waiver of claim for recovery from the other party
entered into in writing by the insured thereunder prior to any loss or damage
shall not affect the validity of said policy or the right of the insured to
recover thereunder. Without limiting any release or waiver of liability or
recovery contained in any other Section of this Lease but rather in confirmation
and furtherance thereof, Landlord and Tenant each hereby waive any and every
claim for recovery from the other for any and all loss of or damage to the
Project or the Premises or to the contents thereof, which loss or damage is
covered by valid and collectible fire and extended coverage insurance policies,
to the extent that such loss or damage is recoverable under said insurance
policies. Inasmuch as this mutual waiver will preclude the assignment of any
such claim by subrogation (or otherwise) to an insurance company (or any other
person), Landlord and Tenant each agree to give to each insurance company which
has issued, or in the future may issue, its policies of fire and extended
coverage insurance, written notice of the terms of this mutual waiver, and to
have said insurance policies properly endorsed, if necessary to prevent the
invalidation of said insurance coverage by reason of said waiver.

     C.   At all times during the Term of this Lease, Tenant shall at its sole
cost and expense maintain in full force and effect insurance protecting Tenant
and Landlord and their respective agents and employees, and any other parties
designated by Landlord from time to time, with terms, coverages and in companies
at all times satisfactory to Landlord and with such increases in limits as
Landlord may, from time to time, request. Initially, such coverage shall be in
the following amounts:

          (1)  Comprehensive or Commercial General Liability Insurance,
     including Contractual Liability insuring the indemnification provisions
     contained in this Lease, with limits of not less than One Million Dollars
     ($1,000,000.00) combined single limit per occurrence for Bodily Injury,
     Death and Property Damage, and umbrella coverage of not less than Three
     Million Dollars ($3,000,000). The Comprehensive or Commercial General
     Liability policy shall include the Landlord and Landlord's building manager
     as additional insureds, with a severability of interest endorsement.

          (2)  Insurance against (a) "All Risks" of physical loss covering the
     tenant improvements (if any) described in Item 14

                                  - 17 -

<PAGE>

     of the Schedule, the Work, movable fixtures, office equipment, furniture,
     trade fixtures, merchandise and all other items of Tenant's property on the
     Premises, and (b) loss of use of the Premises.

     D.   Tenant hereby agrees to, prior to the commencement of the Term hereof
and prior to the expiration of any policy, furnish Landlord certificates
evidencing that all required insurance is in force and providing that such
insurance may not be cancelled or changed without at least thirty (30) days,
prior written notice to Landlord and Tenant (unless such cancellation is due to
nonpayment of premiums, in which event ten (10) days' prior written notice shall
be provided).

     E.   Tenant hereby agrees to indemnify, defend and hold harmless Landlord
and its officers, directors, servants, agents and employees against any claims
or liability for damage to person or property (or for loss or misappropriation
of property) occurring in the Premises or Project, arising from any breach or
default on the part of Tenant during the Term of this Lease or from any act or
omission of Tenant or of any employee, agent, servant, invitee or contractor of
Tenant, and from any costs relating thereto (including, without limitation,
attorneys' fees).

     Landlord hereby agrees to indemnify, defend and hold harmless Tenant and
its officers, directors, servants, agents and employees against any claims or
liability for damage to person or property (or for loss or misappropriation of
property), proximately caused by the intentional misconduct or sole negligence
of Landlord or of any employee, agent, servant, invitee or contractor of
Landlord, and from any costs relating thereto (including, without limitation,
attorneys' fees); provided, however, that such indemnification shall be
effective only to the extent of the insurance proceeds recoverable and recovered
under Landlord's general liability insurance policy or policies covering the
Building, together with the amount of any deductible carried by Landlord under
such policy.

     9.   FIRE AND OTHER CASUALTY.

     A.   In the event that (i) the Premises are made substantially untenantable
by fire or other casualty, including damage or casualties of war, and Landlord
shall decide not to restore or repair the same, or (ii) the Building is so
damaged by fire or other casualty that Landlord shall decide to demolish or not
rebuild the same, then, in either of such events, either Landlord or Tenant
shall have the right to terminate this Lease by notice to the other within
ninety (90) days after the date of such fire or other casualty.

     B.   If the Premises or the Building are made untenantable by fire or other
casualty, and this Lease is not terminated pursuant to Section 9A above,
Landlord shall, to the extent permitted by any mortgages or Ground Leases with
respect to the Premises and the Project, immediately take such action as is
necessary to make applicable insurance proceeds available and to use the same to
reconstruct, repair and restore the Building and the Premises, subject to zoning
laws and building codes then in effect, or, if any portion of the Premises has
been leased on an "as is" basis, including only improvements similar to those
located in such portion of the Premises on the Commencement Date or the date on
which such

                                    - 18 -

<PAGE>

portion was added to the Premises, if later than the Commencement Date (herein,
the improvements Landlord is required to make are called the "Required
Improvements"), and at Landlord's option Tenant may be permitted or required to
devote the proceeds of its insurance described in Section 8C(2)(a) to cause
restoration of tenant improvements over and above the Required Improvements,
and pay for the same to Landlord or through Landlord as if newly done pursuant
to Section 5 of this Lease. In the event a fire or other casualty occurs and
both Landlord and Tenant are insured, it is agreed that the coverage of the
Landlord shall be primary and that Landlord's recovery in no event shall be
reduced by any insurance recovery to Tenant.

     C.   Notwithstanding anything in this Section 9 to the contrary (except
that Section 9A shall supersede this Section 9C), if all or any portion of the
Premises shall be made untenantable by a fire or other casualty, Landlord shall
with reasonable promptness, cause a registered architect selected by Landlord
and licensed to do business in Illinois to estimate the amount of time required
to substantially complete repair and restoration of the Premises and make the
Premises tenantable again, using standard working methods. If the estimate
indicates that the Premises cannot be made tenantable within twelve (12) months
from the date the repair and restoration is started, either party shall have the
right to terminate this Lease by giving to the other notice of such election
within ten (10) days after its receipt of the architect's certificate. If the
estimate of the registered architect indicates that the Premises can be made
tenantable within twelve (12) months from the date the repair and restoration is
started, or if neither party terminates this Lease pursuant to this Section 9C,
Landlord shall proceed with reasonable promptness to repair and restore the
Premises, provided that if the estimate of the registered architect indicates
that the Premises can be made tenantable within twelve (12) months from the date
repair and restoration is started, and if Landlord does not repair and restore
the Premises within said twelve (12) month period, which twelve (12) month
period shall be extended to the extent of any Reconstruction Delays, then Tenant
may terminate this Lease upon fifteen (15) days' prior written notice to
Landlord. For purposes of this Lease, the term "Reconstruction Delays" shall
mean: (i) any delays caused by the insurance adjustment process, (ii) any delays
caused by Tenant, and (iii) any delays caused by events beyond Landlord's
reasonable control.

     D.   In the event that this Lease is terminated pursuant to Section 9A or
Section 9C above, rent shall be apportioned on a per diem basis and be paid to
the date of the fire or other casualty. In the event that such fire or casualty
renders all or any portion of the Premises untenantable and this Lease is not
terminated pursuant to Section 9A or Section 9C, then subject to the last
sentence of this Section 9D, the rent provided for in this Lease shall abate on
a per diem basis during the period of repair and restoration until the Premises
are tenantable again, and the abatement shall be in an amount bearing the same
ratio to the total amount of rent due for such period as the untenantable
portion of the Premises from time to time bears to the entire Premises. Any
provision hereof notwithstanding, Tenant's rent shall not abate if its
negligence was the cause of the fire or other casualty; and whether or not the
Lease is terminated, Tenant's recovery shall be limited to the amount necessary
to cause restoration of the tenant improvements as described in this Section 9.

                                    - 19 -

<PAGE>

     10.  RIGHTS RESERVED TO THE LANDLORD. Landlord reserves the following
rights, exercisable without notice to Tenant except as otherwise expressly
provided herein, and without liability to Tenant for damage or injury to
property, person or business (all such claims being hereby released, except to
the extent they are caused by Landlord's negligence), and without effecting an
eviction or disturbance of Tenant's use or possession or giving rise to any
claim for offsets, or abatements of rent or affecting any of Tenant's
obligations under this Lease. Specification of the rights reserved to Landlord
herein shall not exclude any right accruing to Landlord by operation of law or
reserved specifically or by inference from any provision contained in this
Lease:

     A.   Name: To change the Project's name or street address, provided,
          ----
however, that with respect only to a change of street address, if the same is
voluntarily undertaken by Landlord, Landlord shall give 60 days prior notice to
Tenant and shall reimburse Tenant's reasonable costs incurred in changing the
street address on printed materials.

     B.   Signs: To install, affix and maintain any and all signs on the
          -----
exterior and interior of the Building. No signs visible from the exterior of the
Building or from within its lobbies or common corridors shall be permitted to be
installed in the Premises by Tenant without Landlord's approval of the sign and
the location thereof, which may be withheld in Landlord's sole discretion.
Landlord reserves the right to remove at Tenant's expense any such sign not so
approved by Landlord.

     C.   Windows: To designate and approve, prior to installation, all types of
          -------
window shades, blinds, drapes, awnings, window ventilators and other similar
equipment and to control all the internal lighting that may be visible from the
exterior of the Building.

     D.   Service Contracts: To designate all sources furnishing sign painting
          -----------------
and lettering, ice and drinking water, towels, toilet supplies, beverages, food
service, shoe shining or other services on the Premises, provided that the
rates for such services as are designated by Landlord are reasonably competitive
with rates charged therefor in the Chicago metropolitan area. No vending or
dispensing machines of any kind shall be placed in or about the Premises
without the prior written consent of Landlord.

     E.   Keys: To retain at all times and to use passkeys to the Premises and
          ----
keys to all locks within and into the Premises. No locks or bolts shall be
altered, changed or added without the prior written consent of Landlord.

     F.   Access for Repairs, etc.: To have access to the Premises to perform
          ------------------------
its duties and obligations under this Lease and to inspect the Premises, make
repairs, alterations, additions or improvements, whether structural or
otherwise, in and about the Premises, the Project or any part thereof as set
forth in and subject to various Sections of this Lease including, without
limitation, Section 5 and Section 10N.

     G.   Occupancy: To decorate, remodel, repair, alter or otherwise prepare
          ---------
the Premises for reoccupancy at any time after Tenant vacates or abandons the
Premises and defaults in the payment

                                    - 20 -

<PAGE>

        of rent. Such acts of Landlord shall not relieve Tenant of its
        obligation to pay rent to the Termination Date.

               H. Rights to conduct Businesses: To grant to anyone the exclusive
                  ----------------------------
        right to conduct any business or render any service in the Project
        provided such exclusive right shall not operate to exclude Tenant from
        the use permitted by this Lease.

               I. Heavy Equipment: To approve the weight, size or location of
                  ---------------
        safes and other heavy equipment and articles in and about the Premises
        and the Project and to require all such items and furniture to be moved
        into and out of the Building or anywhere else in the Project and the
        Premises only at such times and in such manner as Landlord shall direct
        in writing. Movement of Tenant's property into or out of the Project and
        within the Project is entirely at the risk and responsibility of Tenant.
        Any furniture, equipment, curtains and similar articles desired to be
        removed from the Premises or the Building shall be listed in a written
        notice from Tenant to Landlord and a removal permit therefor shall be
        obtained from Landlord prior to removal thereof.

               J. Show Premises: To show the Premises to prospective tenants or
                  -------------
        brokers during the last year of the Term of this Lease or the last year
        of any extension thereof or to show the Premises to prospective
        purchasers at all reasonable times, provided prior notice is given to
        Tenant in each case and Tenant's use and occupancy of the Premises shall
        not materially be inconvenienced by any such action of Landlord.

               K. Close Protect: To close or restrict access to the Project
                  -------------
        during such hours as Landlord shall from time to time reasonably
        determine, and on Holidays subject, however, to Tenant's right to
        admittance at all times under such regulations as Landlord may prescribe
        from time to time which may include, by way of example but not of
        limitation, that persons entering or leaving the Project identify
        themselves to a security guard by registration or otherwise and that
        said persons establish their right to enter or leave the Project.

               L. Substitution of Space: At any time hereafter, Landlord may
                  ---------------------
        relocate all of the Premises to another area in the Project (the "new
        premises") upon sixty (60) days' prior written notice, provided that:

                    (1) the new premises shall be similar to the Premises in
               area and suitable for the use which Tenant had made of the
               Premises;

                    (2) such change shall be made in order to put into the
               Premises a major tenant in the Project;

                    (3) Landlord will pay all of the costs of improving the new
               premises so they are substantially similar to the Premises;

                    (4) Landlord shall pay all of Tenant's moving costs,
               reasonable costs of new stationery and announcements and other
               reasonable expenses incurred in connection with such move; and

                                     -21-
<PAGE>

               (5) Such move shall be made during evenings, weekends or
          otherwise so as to incur the least inconvenience to Tenant under the
          circumstances.

          Tenant shall cooperate with Landlord in all reasonable ways to
     facilitate the move to the new premises including, by way of example but
     not of limitation, designating locations to move furniture and equipment,
     supervising moving of files or fragile equipment, designating location of
     telephone outlets, and listing color of paint and of flooring desired in
     the new premises.

          M.   Use of Lock Box by Landlord: Landlord may from time to time elect
               ---------------------------
    to designate a lock box collection agent (independent agent, bank or other
    financial institution) to act as Landlord's agent for the collection of
    amounts due Landlord. In such event the date of payment of rent or other
    sums paid Landlord through such agent shall be the date of agent's receipt
    of such payment (or the date of collection of any such sum if payment is
    made in the form of a negotiable instrument thereafter dishonored upon
    presentment); however, for purposes of this Lease, no such payment or
    collection shall be deemed "accepted" by Landlord if Landlord issues a check
    payable to the order of the Tenant in the amount sent to the lock box and if
    Landlord mails the check to the Tenant addressed to the place designated in
    this Lease for notice to Tenant within twenty-one (21) days after the amount
    sent by the Tenant is received by the lock box collection agent or if the
    Landlord returns a dishonored instrument within twenty-one (21) days of its
    dishonor. Return of any such sum to Tenant by so sending such a check of the
    Landlord or by so sending a dishonored instrument to the Tenant within the
    appropriate twenty-one (21) day period shall be deemed to be rejection of
    Tenant's tender of such payment for all purposes as of the date of
    Landlord's lock box collection agent's receipt of such payment (or
    collection). The return of Tenant's payment in the manner described in this
    Section 10M shall be deemed not to be a waiver of any breach by Tenant of
    any term, covenant or condition of this Lease nor a waiver of any of
    Landlord's rights or remedies granted in this Lease. The possession of
    Tenant's funds or negotiation of Tenant's negotiable instrument by
    Landlord's agent or Landlord during the applicable twenty-one (21) day
    period shall be deemed not to be a waiver of any defaults of Tenant or any
    rights of Landlord theretofore accrued nor shall any such possession or
    negotiation be considered an acceptance of Tenant's tender.

          N. Repairs and Alterations: At any time Landlord may decorate, make
             -----------------------
    alterations, additions or improvements, structural or otherwise, in or to
    the Project or any part thereof, including the Premises, and perform any
    acts required or permitted hereunder, or related to the safety, protection,
    preservation or improvement of the Project or the Premises, and during such
    operations Landlord shall have the right to take into and through the
    Premises or any part of the Project all material and equipment required and
    to close and temporarily suspend operation of entrances, doors, corridors,
    elevators and other facilities, and to have access to and open all ceilings,
    without liability to Tenant by reason of interference, inconvenience,
    annoyance or loss of business; provided, however, that Landlord shall cause
    as little inconvenience or annoyance to Tenant as is reasonably possible
    under the circumstances, and shall not do any act which would permanently
    reduce the size of the Premises. Landlord shall do any such work during
    ordinary business hours, and Tenant shall pay Landlord for overtime and for
    any other incremental or extra expenses incurred if such work is done during

                                   -22-
<PAGE>

        other hours at Tenant's request. Landlord may do or permit any work
        to be done upon or along, and any use of, any adjacent or nearby
        building, land, street, alley or way.

               O. Mail Chutes: To have access for Landlord and other occupants
                  -----------
        of the Building to any mail chutes according to the rules of the United
        States Postal Service.

               P. Other Rights: All other rights reserved by the Landlord
                  ------------
        pursuant to the provisions of this Lease.

               11.  DEFAULT AND LANDLORD'S REMEDIES.

               A.   Defaults. The occurrence of any of the following shall
                    --------
        constitute a default hereunder:

                    (1) If Tenant defaults in the payment of rent (whether Base
               Rent, Operating Cost Share Rent, Tax Share Rent or Additional
               Rent), or any other sum required to be paid by this Lease;
               provided, however, that Landlord shall not be entitled to
               exercise its remedies set forth herein or at law or in equity
               with respect to such default, unless such default is not remedied
               within five (5) days after written notice thereof by Landlord to
               Tenant;

                    (2) If Tenant defaults in the prompt and full performance or
               observance of any term, covenant, agreement or provision of this
               Lease (except those specified in Subsections (1), (3), (4), (5),
               (6), (7), (8) and (9) of this Section 11A); provided, however,
               that Landlord shall not be entitled to exercise its remedies set
               forth herein or at law or in equity with respect to such default,
               (i) if such default is remedied within seven (7) days after
               written notice thereof by the Landlord, (or if such default
               involves a hazardous condition and it is not cured by Tenant
               immediately upon written notice to Tenant), or (ii) with respect
               to a default which cannot reasonably be cured within seven (7)
               days, if Tenant immediately commences to cure and diligently
               proceeds to complete the cure of such default within a reasonable
               time period which shall in no event extend beyond ninety (90)
               days after Tenant receives written notice of such default;

                    (3) If Tenant abandons or vacates the Premises during
               the Term hereof without rent being paid;

                    (4) If the leasehold interest of Tenant is levied upon under
               execution or is attached under process of law, which levy or
               attachment continues for a period of thirty (30) days;

                    (5) If Tenant becomes insolvent or bankrupt or shall
               generally not pay its debts as they become due or shall admit in
               writing its inability to pay its debts or shall make a general
               assignment for the benefit of creditors;

                    (6) If Tenant shall commence any case, proceeding or other
               action seeking reorganization, arrangement, adjustment,
               liquidation, dissolution or composition of it or its debts under
               any law relating to bankruptcy, insolvency, reorganization or
               relief of debtors, or seeking appointment of a receiver, trustee,
               custodian or other similar official for it or for all or any
               substantial part of its property;

                                     -23-
<PAGE>

                    (7) If Tenant shall take any corporate or other action to
             authorize any of the actions set forth above in Subsections (5) and
             (6) of this Section 11A;

                    (8) If any case, proceeding or other action against Tenant
             shall be commenced seeking to have an order for relief entered
             against it as debtor, or seeking reorganization, arrangement,
             adjustment, liquidation, dissolution or composition of it or its
             debts under any law relating to bankruptcy, insolvency,
             reorganization or relief of debtors, or seeking appointment of a
             receiver, trustee, custodian or other similar official for it or
             for all or any substantial part of its property, and such case,
             proceeding or other action (i) results in the entry of an order for
             relief against it which is not fully stayed within seven (7)
             business days after the entry thereof or (ii) remains undismissed
             for a period of thirty (30) days; or

                    (9) If Tenant does any act, or any other circumstance
             occurs, which this Lease expressly provides is a default hereunder.

             B.     Landlord's Remedies.
                    -------------------

                    (1) Upon the occurrence of any one or more defaults by
             Tenant, Landlord may elect, by written notice to Tenant, to
             terminate this Lease and Tenant's right to the Premises as of the
             date set forth in the notice or, without terminating this Lease, to
             terminate Tenant's right to possession of the Premises as of the
             date set forth in the notice. Upon any termination of this Lease,
             whether by lapse of time or otherwise, or upon any termination of
             Tenant's right to possession without termination of the Lease,
             Tenant shall surrender possession and vacate the Premises and
             deliver possession thereof to Landlord, and Tenant hereby grants to
             Landlord full and free license to enter into and upon the Premises
             with process of law in the event of any such termination of this
             Lease or of Tenant's right to possession, and to repossess Landlord
             of the Premises as of Landlord's former estate and to expel or
             remove Tenant and any others who may be occupying or be within the
             Premises and to remove any and all property therefrom using such
             force as may be necessary without being deemed in any manner guilty
             of trespass, eviction or forcible entry or detainer, and without
             relinquishing Landlord's rights to rent or any other right given to
             Landlord hereunder or by law or in equity. Except as otherwise
             provided in this Section 11, Tenant expressly waives the service of
             any notice of intention to terminate this Lease or to reenter the
             Premises and waives the service of any demand for payment of rent
             or possession and waives the service of any other notice or demand
             prescribed by any statute or other law, and agrees that the simple
             breach of any of the covenants or conditions of this Lease shall,
             without the service of any demand or notice whatsoever, constitute
             a forcible detainer by Tenant of the Premises within the meaning of
             the statutes of the State of Illinois.

                    (2) If Landlord elects to terminate Tenant's right to
             possession only without terminating the Lease, and Landlord does so
             elect, Landlord may at Landlord's option enter into the Premises,
             remove Tenant's signs and other evidences of

                                     -24-
<PAGE>

             tenancy, and take and hold possession thereof as set forth in
             subsection B(1) of this Section 11, without such entry and
             possession terminating the Lease or releasing Tenant, in whole or
             in part, from Tenant's obligation to pay the rent hereunder for the
             full Term, and, at Landlord's option, the present value of the
             aggregate amount of the Base Rent, Operating Cost Share Rent and
             Tax Share Rent (based upon the amount thereof for the calendar
             month immediately preceding the month in which the default has
             occurred) for the period from the date stated in the written notice
             terminating possession to the stated end of the Term (such present
             value to be computed on the basis of a per annum discount rate
             equal to three (3) percentage points below the Corporate Base Rate
             at the time of the default) shall be immediately due and payable by
             Tenant to Landlord, together with any other monies due hereunder,
             and Landlord shall have right to immediate recovery of all such
             amounts. In the alternative, Landlord shall have the right from
             time to time, to recover from Tenant, and Tenant shall remain
             liable for, all rent not theretofore accelerated and paid pursuant
             to the foregoing sentence and any other sums thereafter accruing as
             they become due under this Lease during the period from the date
             stated in the notice terminating possession to the stated end of
             the Term. Upon and after entry into possession without termination
             of the Lease, subject to Landlord's right to first rent other
             vacant areas in the Building, Landlord may relet the Premises or
             any part thereof to any person, firm or corporation other than
             Tenant for such rent, for such time (which may be a period
             extending beyond the stated Term of this Lease) and upon such terms
             as Landlord in Landlord's sole discretion shall determine, and
             Landlord shall not be required to accept any tenant offered by
             Tenant or to observe any instructions by Tenant relating to such
             reletting. In any such case, Landlord may make repairs, alterations
             and additions in or to the Premises and redecorate the same to the
             extent deemed necessary or desirable by Landlord, and in connection
             therewith Landlord may change the locks to the Premises, and Tenant
             shall upon written demand pay the cost thereof, together with
             Landlord's expenses of reletting. Any proceeds from the reletting
             of the Premises by Landlord shall be collected by Landlord and
             shall first be applied against the cost and expenses of reentry and
             of reletting the Premises including, but not limited to, all
             brokerage, advertising, legal, alteration, redecoration, repair,
             and other reasonably necessary costs and expenses incurred to
             secure a new tenant for the Premises, and second to the payment of
             rent herein provided to be paid by the Tenant. If the consideration
             collected by Landlord upon any such reletting, after payment of the
             expenses of reletting the Premises, is not sufficient to pay any
             accelerated amounts of rent due and owing and to pay monthly the
             full amount of the rent reserved in this Lease and not theretofore
             accelerated, Tenant shall pay to Landlord the accelerated amounts
             upon demand, and the amount of each monthly deficiency as it
             becomes due. If the consideration collected by Landlord upon any
             such reletting for Tenant's account after payment of the expenses
             of reletting the Premises is greater than the amount necessary to
             pay accelerated amounts of rent due and owing and to pay the full
             amount of the rent reserved in this Lease and not theretofore
             accelerated, the full amount of such excess shall be retained by
             Landlord and in no event shall be payable to Tenant. No such
             reentry, repossession, repairs,

                                     -25-
<PAGE>

             alterations, additions or reletting shall be construed as an
             eviction or ouster of Tenant or as an election on Landlord's part
             to terminate this Lease, unless written notice of such intention is
             given to Tenant, or shall operate to release Tenant in whole or in
             part from any of Tenant's obligations hereunder. Notwithstanding
             any provision hereof which may be to the contrary, Landlord agrees
             to use all reasonable efforts to mitigate damages to the extent
             required by law.

                    (3) If Landlord shall decide to terminate this Lease,
             Landlord shall be entitled to recover from Tenant all of the
             amounts of rent accrued and unpaid for the period up to and
             including the date of the termination, as well as all other
             additional sums for which Tenant is liable, or in respect of which
             Tenant has agreed to indemnify Landlord under any of the provisions
             of this Lease, which may then be owing and unpaid, and all
             reasonable costs and expenses including, without limitation, court
             costs and attorneys' fees incurred by Landlord in the enforcement
             of its rights and remedies hereunder, and in addition, Landlord, at
             its sole option, shall be entitled to recover from Tenant, in lieu
             of any amounts due under Section 11B(2) hereof, and Tenant shall
             pay to Landlord, on demand, as final and liquidated damages (and
             not as a penalty), a sum equal to the amount of Landlord's
             reasonable estimate of the aggregate amount of Base Rent, Operating
             Cost Share Rent, Tax Share Rent and Additional Rent that would be
             payable for the period from the date of such termination through
             the Termination Date, reduced by the then reasonable rental value
             of the Premises for the same period, both discounted to present
             value at the rate per annum equal to three (3) percentage points
             below the Corporate Base Rate at the time of the default. If,
             before presentation of proof of such liquidated damages to any
             court, commission or tribunal, the Premises, or any part thereof,
             shall have been relet by Landlord for such period, or any part
             thereof, the amount of rent payable upon such reletting shall be
             deemed to be the reasonable rental value for the part or the whole
             of the Premises relet during the term of the reletting.

                    (4) Landlord may but shall not be obligated to cure any
             default by Tenant hereunder, but, if Landlord so elects, all costs
             and expenses paid by Landlord in curing such default and legal fees
             in connection therewith shall be Additional Rent due on the next
             rent date.

                    (5) Notwithstanding anything in the Lease to the contrary,
             any and all remedies set forth in this Lease (i) shall be in
             addition to any and all other remedies Landlord may have at law or
             in equity and (ii) shall be cumulative. The waiver by Landlord of
             any breach of any term, covenant or condition herein contained
             shall only be effective if it is in writing and shall not be deemed
             to be a waiver of a continuing or subsequent breach of the same, or
             of any other term, covenant or condition herein contained. The
             acceptance of rent or any other amounts due hereunder shall not be
             construed to be a waiver of any breach by Tenant of any term,
             covenant or condition of this Lease, and if the same shall be
             accepted after the termination of this Lease, by lapse of time or
             otherwise, or of the Tenant's right of possession hereunder, or
             after the giving of any notice, such acceptance shall not
             reinstate, continue or extend the Term of this Lease or affect

                                   -26-
<PAGE>

             any notice given to Tenant prior to the receipt of such
             amounts, it being agreed that after the service of notice or
             the commencement of a suit or after final judgment for
             possession of the Premises, Landlord may receive and collect
             any rent and other sums due, and the payment of the same shall
             not waive or affect said notice, suit or judgment.

                   (6) Notwithstanding any provision in this Lease prohibiting
             Landlord from exercising its rights hereunder or at law or in
             equity if Tenant cures a default within a specified period of time,
             if Tenant shall default (i) in the timely payment of rent (whether
             any or all of Base Rent, Operating Cost Share Rent, Tax Share Rent
             or Additional Rent) three or more times in any period of 12
             consecutive months, or (ii) in the performance of any particular
             term, condition or covenant of this Lease three or more times in
             any period of six consecutive months, then, notwithstanding that
             such defaults shall have each been cured within any applicable cure
             period after notice, if any, as provided in this Lease, any further
             similar default (including, without limitation, with respect to
             non-payment of rent, the further non-payment of any kind of rent
             payable under this Lease) shall not be curable by Tenant and
             Landlord shall have the right to exercise all of the remedies
             provided in this Lease (including, without limitation, any and all
             remedies at law and in equity) immediately after the occurrence of
             such similar default.

                   (7) If the term of any lease, other than this Lease, made by
             the Tenant for any demised premises in the Building or any other
             building owned by Landlord or an affiliate of Landlord shall be
             terminated or terminable after the making of this Lease because of
             any default by the Tenant under such other lease, such fact shall
             empower the Landlord, at Landlord's sole option, to terminate this
             Lease by written notice to the Tenant.

                   (8) In the event that Tenant shall file for protection under
             the Bankruptcy Code now or hereinafter in effect, or a trustee in
             bankruptcy shall be appointed for Tenant, Landlord and Tenant agree
             to the extent permitted by law, to request that the debtor-in-
             possession or trustee-in-bankruptcy, if one shall have been
             appointed, assume or reject this Lease within sixty (60) days
             thereafter.

             12.   HOLDOVER. If Tenant retains possession of the Premises or any
        part thereof after the termination of the Term or any extension thereof,
        by lapse of time or otherwise, Tenant shall become a tenant from month-
        to-month only upon each and all of the terms herein provided as may be
        applicable to such month-to-month tenancy and any such holding over
        shall not constitute an extension of this Lease; provided, however, that
        during such holding over, Tenant shall pay Base Rent, Operating Cost
        Share Rent and Tax Share Rent at 150% of the rate payable for the fiscal
        year, or portion thereof, immediately preceding said holding over,
        computed on a monthly basis for the time Tenant thus remains in
        possession and, in addition, Tenant shall pay Landlord all damages,
        consequential as well as direct, sustained by reason of Tenant's holding
        over. Alternatively, at the election of Landlord expressed in a written
        notice to Tenant and not otherwise, if such retention of possession
        lasts more than sixty (60) days, such retention of possession shall
        constitute a renewal of this Lease for one (1) year; provided,

                                     -27-
<PAGE>

        however, that Tenant shall pay Base Rent in an amount equal to the
        greater of 150% of the rate payable for the immediately preceding fiscal
        year, or portion thereof or 150% of the then current market rate
        (hereinafter defined) as determined by Landlord, and Tenant shall
        continue to make all other payments required under this Lease,
        including, without limitation, Operating Cost Share Rent and Tax Share
        Rent. Neither the acceptance of rent by the Landlord after termination,
        nor the provisions of this Section: (i) shall be construed as, or
        operate as, a renewal or as a waiver of Landlord's right of re-entry or
        right to regain possession by actions at law or in equity or by any
        other right or remedy hereunder, or (ii) shall be construed as, or
        operate as, a waiver of any other right or remedy of Landlord.

               13.  SUBORDINATION TO MORTGAGES, TRUST DEEDS AND GROUND LEASES.

               A.   Subordination. This Lease shall be subordinated to any and
                    -------------
        all Ground Leases now or hereafter in force with respect to the Project
        at the election of the ground lessor under any such Ground Lease. This
        Lease shall be subject to all of the terms and conditions of such Ground
        Leases, which are hereby incorporated in this Lease by this reference,
        and in the event of any conflict between the terms hereof and the terms
        of any such Ground Leases, the terms of such Ground Leases shall
        control. This Lease shall be subordinated to the lien of any and all
        mortgages now or hereafter in force against (a) the Project and (b) any
        and all Ground Leases with respect to the Project, at the election of
        the mortgagee under any such mortgage. Landlord hereby represents that
        as of the date hereof there are no Ground Leases with respect to the
        Project.

               The respective rights to so subordinate this Lease at the
        election of any such ground lessor or mortgagee shall continue during
        any amendment, renewal, modification, consolidation, replacement or
        extension of each such Ground Lease or mortgage, and shall apply to any
        and all advances made or hereafter made on the security of each such
        mortgage.

               Subordination shall be effective at election of any such ground
        lessor or mortgagee. Election shall not be dependent on receipt of
        notice by Tenant of the election to subordinate. Without limiting the
        foregoing, notice of the election to subordinate may be given as
        provided for notices pursuant to this Lease.

               Any subordination at the election of any such ground lessor or
        mortgagee shall be self-operating. Nevertheless, Tenant or its
        successors in interest upon request of Landlord shall promptly
        execute and deliver (within ten (10) days after a request therefor)
        at any time and from time to time upon the request of Landlord, such
        instruments as are reasonably necessary or appropriate in Landlord's
        judgment to evidence such subordination.

               B.   Termination of Ground Lease or Foreclosure of Mortgage.
                    ------------------------------------------------------
        Should any mortgage on the Project or on any Ground Lease be foreclosed
        or if any Ground Lease be terminated and this Lease be continued:

                    (1)  The liability of the mortgagee, ground lessor or
               purchaser at such foreclosure sale shall exist only during the
               time such mortgagee, ground lessor or purchaser is the owner of
               the Project.

                                     -28-
<PAGE>

                    (2)  Tenant shall attorn, as Tenant under this Lease,
               without any deductions or setoffs whatsoever (except that Tenant
               shall receive full credit for any rents theretofore paid by
               Tenant), to the purchaser at the foreclosure sale (or the
               mortgagee if the mortgagee becomes owner of the fee estate or
               lessor under any Ground Lease) or, if any Ground Lease be
               terminated for any reason, Tenant shall be deemed to have
               attorned as Tenant under this Lease to the ground lessor under
               the Ground Lease, and this Lease shall continue in full force and
               effect as a direct lease between and binding upon Tenant and such
               mortgagee or ground lessor, as the case may be. Likewise, Tenant
               will attorn to a leasehold mortgagee in the event a leasehold
               mortgagee should ever become the owner of the leasehold estate
               covered by its mortgage or should become the owner of any new
               lease in replacement or substitution of such leasehold estate.
               Tenant agrees to promptly execute and deliver (within ten (10)
               days after a request therefor) at any time and from time to time
               upon the request of Landlord, or of any ground lessor under any
               such Ground Lease, or of any holder of any such mortgage or
               leasehold mortgage, or of any such purchaser, any instrument
               which, in the sole judgment of such requesting party, may be
               necessary or appropriate in any such foreclosure or termination
               proceeding or otherwise to evidence such attornment.

                    (3)  As used in this Section 13, "mortgage" shall include
               "trust deed" and "mortgagee" shall include "trustee" and
               successors and assigns of such party (whether immediate or
               remote), the purchaser of any mortgage, whether at foreclosure
               or otherwise and the successors, assigns and mortgagees of such
               purchaser (whether immediate or remote).

               C.   Security Deposit. The mortgagee under a mortgage and the
                    -----------------
          lessor under any Ground Lease shall have no responsibility for the
          return of the security deposit, if any, except to the extent the
          security deposit is held by such mortgagee or ground lessor.

               D.   Notice and Right to Cure. Landlord hereby notifies Tenant
                    ------------------------
          that the Project is subject to the mortgages set forth on Appendix E
          attached hereto (Mortgages Currently Affecting the Project), and
          Landlord agrees promptly to notify Tenant of the placing of any
          additional Ground Leases, mortgages or trust deeds against the real
          property or leasehold estate of which the Premises form a part.

               Tenant agrees to give the mortgagees shown on Appendix E and any
          other mortgagee or holder of a deed of trust or lessor of any Ground
          Lease, by registered mail, a copy of any notice of default served upon
          the Landlord, provided that prior to such notice Tenant has been
          notified, in writing (by way of notice of Assignment of Rents and
          Leases, or otherwise), of the address of such mortgagee, holder of a
          deed of trust or lessor under any Ground Lease. Tenant further agrees
          that if Landlord shall have failed to cure such default within the
          time provided for in this Lease, then such mortgagee, holder of a deed
          of trust or lessor under any Ground Lease shall have an additional
          thirty (30) days within which to cure such default, or if such default
          cannot be cured within that time, such mortgagee, holder of a deed of
          trust or lessor under any Ground Lease shall have such additional time
          as may be necessary to cure such default, provided that within such
          thirty (30) days, any mortgagee, holder of a deed of trust or lessor
          under any Ground

                                   -29-
<PAGE>

     Lease, as the case may be, has commenced and is diligently pursuing the
     cure of such default (including but not limited to commencement of
     foreclosure or lease forfeiture proceedings, if necessary to effect such
     cure), and Tenant shall not pursue any of the remedies it may have for such
     default and this Lease shall not be terminated, while such cure is being
     diligently pursued, so long as the default is completely cured within a
     reasonable time thereafter. During the period between the giving of such
     notice and the remedying of Landlord's default, the rent herein recited
     shall be abated and apportioned to the extent that any part of the Premises
     shall be untenantable.

          14.  ASSIGNMENT AND SUBLETTING BY TENANT.

          A.   Tenant shall not, without the prior written consent of Landlord
     in each instance, (i) assign, transfer, mortgage, pledge, hypothecate or
     encumber or subject to or permit to exist upon or be subjected to any lien
     or charge, this Lease or any interest under it, (ii) allow to exist or
     occur any transfer of or lien upon this Lease or the Tenant's interest
     herein by operation of law, (iii) sublet the Premises or any part thereof,
     or (iv) permit the use or occupancy of the Premises or any part thereof for
     any purpose not provided for under Section 6 of this Lease or by anyone
     other than the Tenant and Tenant's employees. In no event shall this Lease
     or any interest herein be assigned or assignable by voluntary or
     involuntary bankruptcy proceedings or by operation of law or otherwise, and
     in no event shall this Lease or any rights or privileges hereunder be an
     asset of Tenant under any bankruptcy, insolvency or reorganization
     proceedings, except as provided by law.

          B.   Consent by Landlord to any assignment, subletting, use,
     occupancy, transfer or encumbrance shall not operate to relieve Tenant from
     any covenant, liability or obligation hereunder (whether past, present or
     future), including, without limitation, the obligation to pay rent, except
     to the extent, if any, expressly provided for in such consent, or be deemed
     to be a consent to any subsequent assignment, subletting, use, occupancy,
     transfer or encumbrance. Tenant shall pay all of Landlord's costs, charges
     and expenses, including without limitation, reasonable attorney's fees,
     incurred in connection with any assignment, subletting, use, occupancy,
     transfer or encumbrance made or requested by Tenant.

          C.   Tenant shall, by notice in writing, advise Landlord of its
     intention from, on and after a stated date (which shall not be less than
     sixty (60) days after the date of Tenant's notice) to assign this Lease or
     sublet any part or all of the Premises for the balance or any part of the
     Term, and, in such event, Landlord shall have the right, to be exercised by
     giving written notice to Tenant within thirty (30) days after receipt of
     Tenant's notice, to terminate this Lease with respect to the space
     described in Tenant's notice as of the date stated in Tenant's notice for
     the commencement of the proposed assignment or sublease. Tenant's notice
     shall include the name and address of the proposed assignee or subtenant, a
     true and complete copy of the proposed assignment or sublease and
     sufficient information as Landlord deems necessary to permit Landlord to
     determine the financial responsibility and character of the proposed
     assignee or subtenant. If Tenant's notice covers all of the Premises and if
     Landlord exercises its right to terminate this Lease as to such space, then
     the Term of this Lease shall expire and end on the commencement date stated
     in Tenant's notice as

                                     -30-
<PAGE>

        fully and completely as if that date had been the Termination Date. If,
        however, Tenant's notice covers less than all of the Premises, and if
        Landlord exercises its right to terminate this Lease with respect to
        such space described in Tenant's notice, then as of the commencement
        date stated in Tenant's notice, the rent reserved herein shall be
        adjusted on the basis of the number of rentable square feet retained by
        Tenant, and this Lease as so amended, shall continue thereafter in full
        force and effect. If Landlord, upon receiving Tenant's notice, does not
        exercise its right to terminate as aforesaid, Landlord will not
        unreasonably withhold its consent to Tenant's assignment of this Lease
        or subletting the space covered by its notice. Without limitation, it
        shall be deemed reasonable for Landlord to withhold its consent to
        Tenant's assignment of this Lease or subletting the space covered by its
        notice if the proposed assignee or sublessee is a tenant or occupant of
        the Building or an affiliate (a person controlling, controlled by or
        under common control with) of a tenant or occupant of the Building.

               D.   If Tenant, having first obtained Landlord's consent to any
        assignment or sublease, or if Tenant or a trustee in bankruptcy for
        Tenant pursuant to the Bankruptcy Code, shall assign this Lease or
        sublet the Premises, or any part thereof, at a rental or for other
        consideration in excess of the aggregate of the Base Rent, Operating
        Cost Share Rent and Tax Share Rent due and payable by Tenant under this
        Lease, then Tenant shall pay to Landlord as Additional Rent sixty
        percent (60%) of all of such excess rent or other consideration within
        ten (10) days after receipt thereof from time to time.

               E.   If Tenant shall assign this Lease as permitted herein, the
        assignee shall expressly assume all of the obligations of Tenant
        hereunder and agree to comply with and be bound by all of the terms,
        provisions and conditions of this Lease, in a written instrument
        satisfactory to Landlord and furnished to Landlord not later than
        fifteen (15) days prior to the effective date of the assignment. If
        Tenant shall sublease the Premises as permitted herein, Tenant shall
        obtain and furnish to Landlord, not later than fifteen (15) days prior
        to the effective date of such sublease and in form satisfactory to
        Landlord, the written agreement of such subtenant that it shall comply
        with and be bound by all of the terms, provisions and conditions of this
        Lease and that it will attorn to Landlord, at Landlord's option and
        written request, in the event this Lease terminates before the
        expiration of the sublease.

               F.   If Tenant is a corporation whose stock is not publicly
        traded, any transaction or series of transactions (including, without
        limitation, any dissolution, merger, consolidation or other
        reorganization of Tenant, or any issuance, sale, gift, transfer or
        redemption of the beneficial ownership of any capital stock of Tenant,
        whether voluntary, involuntary or by operation of law, or any
        combination of any of the foregoing transactions) resulting in the
        transfer of control of Tenant, other than by reason of death or an
        initial public offering by Tenant, shall be deemed to be a voluntary
        assignment of this Lease by Tenant subject to the provisions of this
        Section 14. If Tenant is a partnership, any transaction or series of
        transactions (including without limitation any withdrawal or admittance
        of a partner or any change in any partner's interest in Tenant, whether
        voluntary, involuntary or by operation of law, or any combination of any
        of the foregoing transactions) resulting in the transfer of control of
        Tenant, other than by reason of death, shall be deemed to be a voluntary

                                   -31-
<PAGE>

        assignment of this Lease by Tenant subject to the provisions of this
        Section 14. The term "control" as used in this Section 14F means the
        power to directly or indirectly direct or cause the direction of the
        management or policies of Tenant. If Tenant is a corporation, a change
        or series of changes in ownership of stock which would result in direct
        or indirect change in ownership by the stockholders or an affiliated
        group of stockholders of less than fifty percent (50%) of the
        outstanding stock as of the date of the execution and delivery of this
        Lease shall not be considered a change of control.

               G.   Any assignment, subletting, use, occupancy, transfer or
        encumbrance of this Lease or the Premises without Landlord's prior
        written consent shall be of no effect and shall, at the option of
        Landlord, constitute a default under this Lease.

               15.  SALE BY LANDLORD. In the event of sale, conveyance,
        assignment or transfer by Landlord of its interest in the Project or in
        the Building or in this Lease, the same shall operate to release
        Landlord (subject to the second paragraph of Section 17 hereof) from any
        future obligations and any future liability for or under any of the
        covenants or conditions, express or implied, herein contained in favor
        of Tenant, and in such event, and with respect to such obligations,
        covenants and conditions, Tenant agrees to look solely to the successor
        in interest of Landlord in and to this Lease. This Lease shall not be
        affected by any such sale, conveyance or transfer.

               16.  ESTOPPEL CERTIFICATE. Landlord shall, at the request of
        Tenant and Tenant shall, at the request of Landlord at any time and from
        time to time upon not less than ten (10) days' prior written notice,
        execute, acknowledge in recordable form, and deliver to the other, or
        for the Tenant to its auditor or a prospective purchaser of its business
        or assets, or to its assignee or subtenant if acceptable to Landlord, or
        for the Landlord to Landlord's mortgagee, the lessor under any Ground
        Lease, auditors or a prospective purchaser of the Project or any part
        thereof, a certificate stating that this Lease is unmodified and in full
        force and effect (or, if modified, stating the nature of such
        modification and certifying that this Lease, as so modified, is in full
        force and effect), and the dates to which the rent and other charges are
        paid, and that Tenant is paying rent on a current basis with no offsets
        or claims, and there are not, to Tenant's or Landlord's knowledge, as
        the case may be, any uncured defaults on the part of Landlord or of
        Tenant (or specifying such offsets, claims or defaults, if any are
        claimed). Such certificate may require the party giving it to specify
        the date of commencement of rent, the Commencement Date, the Termination
        Date, the Base Rent, current Operating Cost Share Rent and Tax Share
        Rent estimates, the date to which rent has been paid, whether or not
        Landlord has completed any improvements required to be made to the
        Premises and such other matters as may be required. It is expressly
        understood and agreed that any such statement may be relied upon by any
        prospective purchaser or encumbrancer of all or any portion of the
        Project or by any ground lessor, or by a purchaser or assignee or lender
        to Tenant or to auditors of either party hereto or by any other person
        to whom it is delivered. The failure to deliver such statement within
        the time required hereunder shall, at the option of the requesting
        party, be a default under this Lease, or be conclusive evidence, binding
        upon the nonperforming party that this Lease is in full force and
        effect, without modification except as may be represented by the
        requesting party, that there are no uncured defaults by the requesting
        party

                                     -32-
<PAGE>

        and that not more than one (1) month's rent has been paid in advance,
        and the nonperforming party shall be estopped from asserting any
        defaults known to it at that time.

               17.  SECURITY DEPOSIT. Tenant has deposited with Landlord
        security for the full and faithful performance of every provision of
        this Lease to be performed by Tenant in the amount, if any, set forth as
        Item 11 in the Schedule. If Tenant defaults with respect to any
        provision of this Lease, Landlord may use all or any part of this
        security deposit for the payment of any rent and any other sum due or in
        default, or for the payment of any other amount which Landlord may spend
        or become obligated to spend by reason of Tenant's default, or to
        compensate Landlord for any loss or damage which Landlord may suffer by
        reason of Tenant's default. If any portion of such deposit is to be
        used, Tenant shall within fifteen (15) days after written demand
        therefor deposit cash with Landlord in an amount sufficient to restore
        the security deposit to its original amount and Tenant's failure to do
        so shall be a material breach of this Lease. Landlord shall not be
        required to keep this security deposit separate from its general funds
        and Tenant shall not be entitled to interest on such deposit. If Tenant
        shall fully and faithfully perform every provision of this Lease to be
        performed by it, the security deposit or any balance thereof shall be
        returned to Tenant (or, at Landlord's option, to the last assignee of
        Tenant's interest hereunder) at the expiration of this Lease and upon
        vacation of the Premises in accordance with the provisions hereof. Said
        security deposit shall not be deemed an advance payment of rent or a
        measure of Landlord's damages for any default hereunder by Tenant.

               Tenant acknowledges that Landlord has the right to transfer all
        or any part of its interest in the Project or this Lease, and Tenant
        agrees that in the event of any such transfer, Landlord shall have the
        right to transfer such security deposit to the transferee. Upon delivery
        by Landlord to Tenant of such transferee's written acknowledgement of
        its receipt of such security deposit, Landlord shall thereby be released
        by Tenant from all liability or obligation for the return of such
        deposit and Tenant agrees to look solely to such transferee for the
        return of the security deposit.

               18.  EXCUSE OF LANDLORD'S INABILITY TO PERFORM; LANDLORD'S
        DEFAULT. Except as specifically provided to the contrary in this Lease,
        this Lease and the obligation of Tenant to pay rent hereunder and
        perform all of Tenant's covenants and agreements hereunder shall not be
        impaired nor shall Landlord be in default hereunder because Landlord is
        unable to fulfill any of its obligations under this Lease, if Landlord
        is prevented or delayed from so doing by any of the following (which
        shall be referred to herein as a "Force Majeure"): any accident,
        breakage, repairs, alterations, improvements, strike or labor troubles,
        or any other cause whatsoever beyond the reasonable control of Landlord,
        including, but not limited to, energy shortages or governmental
        preemption in connection with a national emergency, or by reason of
        government laws or any rule, order or regulation of any department or
        subdivision thereof of any governmental agency, or by reason of the
        conditions of supply and demand which have been or are affected by war
        or other emergency.

               19.  PERSONAL PROPERTY AND TENANT FIXTURES. Tenant hereby conveys
        to Landlord all of the personal property and Tenant's fixtures situated
        and to be situated on the Premises as security for

                                     -33-
<PAGE>

the payment of all rent due or to become due hereunder. Said property shall not
be removed therefrom without the consent of Landlord until all rent due or to
become due hereunder shall have first been paid and discharged. It is intended
by the parties hereto that this Lease constitutes a security agreement creating
a security interest in and to such property, subject to the liens of any
existing creditors, and Landlord, upon default of Tenant in the payment of rent,
shall have all the rights of a secured party, as provided in the Illinois
Uniform Commercial Code, as from time to time in effect. Landlord shall have the
right to file this security agreement as a financing statement, after the
occurrence of a default by Tenant which is not cured within any applicable cure
period.

     20.  NOTICES. All notices and approvals to be given by one party to the
other party under this Lease shall be given in writing, mailed or delivered as
follows:

     A.   To Landlord as follows:

Teachers Insurance and Annuity                  Teachers Insurance and Annuity
 Association of America                          Association of America
c/o Office of the Building                      730 Third Avenue
 Manager                                        New York, New York 10017
676 St. Clair                                   Attn: Vice President
Chicago, Illinois 60611

or to such other person at such other address designated by notice to Tenant.

     B.   To Tenant at the place set forth as Item 12 on the Schedule until
Tenant takes possession of the Premises, and thereafter at the Premises or at
such other address designated by notice to Landlord, with a copy to Scott L.
Glickson, Esq., Gordon & Glickson, P.C., 444 North Michigan Avenue, Suite 3600,
Chicago, IL 60611.

     Mailed notices shall be sent by United States Certified or Registered Mail,
postage prepaid. Mailed notices shall be deemed to have been given upon posting
in the United States mails, and notices delivered personally shall be deemed to
have been given upon delivery or attempted delivery.

     21.  QUIET POSSESSION. So long as Tenant shall observe and perform the
covenants and agreements binding on it hereunder, Tenant shall at all times
during the Term herein granted and subject to the provisions of this Lease
peacefully and quietly have and enjoy the possession of the Premises without any
encumbrance or hindrance by, from or through Landlord, its successors or
assigns.

     22.  REAL ESTATE BROKER. Tenant represents that it has not dealt with any
real estate broker except for The John Buck Company and that broker listed, if
any, in Item 13 in the Schedule, with respect to this Lease and, to its
knowledge no other broker initiated or participated in the negotiation of this
Lease, submitted or showed the Premises to Tenant or is entitled to any
commission in connection with this Lease. Tenant agrees to indemnify and hold
Landlord harmless from all claims from any other real estate broker for
commission or fees in connection with this Lease.

                                     -34-
<PAGE>

     23.  CONDEMNATION. If all or any portion of the Project or Premises are
taken by eminent domain so that the Premises cannot be reasonably used by Tenant
for the purposes for which they are demised, then at the option of either party
this Lease may be terminated effective as of the date of the taking and all rent
reserved hereunder shall be paid to the date of such taking. The entire award
for any total or partial taking shall be paid to and retained by Landlord. If
any condemnation proceeding shall be instituted in which it is sought to take or
damage any part of the Project, or if the grade of any street or alley adjacent
to the Project is changed by any competent authority and such change of grade
makes it necessary or desirable to remodel the Project to conform to the changed
grade, Landlord shall have the right to terminate this Lease upon not less than
ninety (90) days' notice prior to the date of termination designated in the
notice. No money or other consideration shall be payable by Landlord to Tenant
for said termination, and the Tenant shall have no right to share in the
condemnation award or in any judgment for damages caused by said eminent domain
proceeding.

     24.  SPRINKLERS. If the sprinkler system installed at the Project or any of
its appliances shall be damaged or injured or not in proper working order by
reason of any act or omission of Tenant, Tenant's agents, servants, employees,
licensees or invitees, Tenant shall forthwith restore the same to good working
condition at its own expense. Tenant shall not do or permit anything to be done
upon the Premises, or bring or keep anything thereon which is in violation of
rules, regulations and requirements of the Illinois Inspection and Rating
Bureau, Fire Insurance Rating Organization or any similar authority having
jurisdiction over the Building, and if the Board of Fire Underwriters or Fire
Insurance Exchange or any bureau, department or official of the state or city
government, requires or recommends that any changes, modifications, alterations
or additional sprinkler heads or other equipment be made or supplied by reason
of Tenant's business or acts or the location of partitions, trade fixtures, or
other contents of the Premises, or if any such changes, modifications,
alterations, additional sprinkler heads or other equipment, become necessary to
prevent the imposition of a penalty or charge against the full allowance for a
sprinkler system in the fire insurance rate as fixed by said Exchange, or by any
fire insurance company, Tenant shall, at Tenant's expense, promptly make and
supply such changes, modifications, alterations, additional sprinkler heads or
other equipment.

     25.  MISCELLANEOUS.

     A.   Covenants Binding on Successors. Subject to the terms and provisions
          -------------------------------
of Section 14 of this Lease, each provision of this Lease shall extend to and
shall, as the case may require, bind and inure to the benefit of Landlord and
Tenant and their respective heirs, legal representatives and successors and
assigns.

     B.   Date Payments Are Due. All amounts owed to Landlord hereunder, for
          ---------------------
which the date of payment is not expressly fixed herein, shall be paid within
thirty (30) days from the date Landlord renders statements of account therefor
and shall bear interest at the rate provided in Section 2D(3) from the date due
until paid.

     C.   Meaning of "Re-entry" and "Landlord". The words "re-enter" and "re-
          ------------------------------------
entry" as used in this Lease are not restricted to their technical legal
meaning. The term "Landlord," as used in

                                     -35-
<PAGE>

this Lease, means only the landlord from time to time, and upon conveying or
transferring its interest, such conveying or transferring landlord shall be
relieved from any further obligation or liability pursuant to Sections 13B(1),
13C, 15 and 17 of this Lease.

     D.   Time Is of the Essence. Time is of the essence of this Lease and each
          ----------------------
and all of its provisions.

     E.   No Option. Submission of this instrument for examination or signature
          ---------
by Tenant does not constitute a reservation of or option for lease, and it is
not effective as a lease or otherwise until execution and delivery by both
Landlord and Tenant.

     F.   Severability. The invalidity or unenforceability of any provision
          ------------
hereof shall not affect or impair any other provisions.

     G.   Governing Laws. This Lease shall be governed by and construed pursuant
          --------------
to the laws of the State of Illinois.

     H.   Lease Modification. Should any mortgage require a modification of this
          ------------------
Lease, which modification will not bring about any increased cost or expense to
Tenant or in any other way substantially change the rights and obligations of
Tenant hereunder, Tenant agrees that this Lease may be so modified.

     I.   No Oral Modification. No subsequent alteration, amendment, change or
          --------------------
addition to this Lease shall be binding upon Landlord or Tenant unless in
writing signed by both parties.

     J.   Litigation and Arbitration Costs. In the event of any litigation or
          --------------------------------
arbitration between the parties hereto with respect to the enforcement or
interpretation of this Lease, the nonprevailing party shall pay the attorneys'
fees, court costs and other costs of the prevailing party, provided that Tenant
shall notify Landlord of any alleged breach of Landlord's obligations under this
Lease and shall take no action with respect to such breach as long as Landlord
immediately commences to cure and diligently proceeds to complete the cure of
said breach within a reasonable time period. Each party hereto shall pay the
attorneys' fees, court costs (if any) and other costs incurred by the other
party in any litigation, negotiation or transaction in which such party causes
the other party, without the other party's fault, to become involved or
concerned (including, without limitation, any request for Landlord's consent to
a sublet or assignment).

     K.   Captions. The marginal headings and titles to the paragraphs of this
          --------
Lease are not a part of this Lease and shall have no effect upon the
construction or interpretation of any part hereof.

     L.   Remedies and Rights May Be Exercised by Landlord In Its Own Name;
          -----------------------------------------------------------------
Authority to Execute This Lease. All rights and remedies of Landlord under this
-------------------------------
Lease, or that may be provided by law, may be exercised by Landlord in its own
name individually, or in its name by any agent thereof, and all legal
proceedings for the enforcement of any such rights or remedies, may be commenced
and prosecuted to final judgment and executed by Landlord in its own name
individually or in its name by any agent thereof. Landlord and Tenant each
represents to the other that each has full power and authority to

                                     -36-
<PAGE>

        execute this Lease and to make and perform the agreements herein
        contained.

               M.   Payments to Affiliates.  Nothing in this Lease shall be
                    ----------------------
        construed to prevent Landlord from paying for services rendered or
        materials delivered with respect to the Project or to the Premises
        (including, without limitation, management services and contracting
        out capital improvements or other capital repairs or construction
        items) by affiliates of Landlord provided that the fees or costs of
        such services and materials are at market rates in the Chicago
        metropolitan area. All such fees or costs paid by Landlord to such
        affiliates shall be deemed to constitute Operating Costs on the same
        terms and conditions as if such fees and costs were paid to
        non-affiliates of Landlord.

               N.   Entire Agreement. This Lease (including, without limitation,
                    ----------------
        any Rider attached hereto and signed by both parties and Appendices A
        through E, all of which are incorporated herein by this reference)
        constitutes the entire agreement between the Landlord and the Tenant.
        Tenant acknowledges that it has not been induced to enter this Lease by
        any promises, assurances, agreements, statements or representations
        (collectively, "Representations") which are not set forth in this Lease
        (including without limitation any Representations concerning Operating
        Costs or Taxes). Tenant acknowledges that it has not relied on any such
        Representations, agrees that no such Representations shall be used in
        the construction or interpretation of this Lease and agrees that
        Landlord shall have no liability for any consequences arising as a
        result of any such Representations.

               O.   Landlord's Title. Landlord's title is and always shall be
                    ----------------
        paramount to the interest of Tenant, and nothing herein contained shall
        empower Tenant to do any act which can, shall or may encumber Landlord's
        title.

               P.   Light and Air Rights. This Lease does not grant any rights
                    --------------------
        to light or air over or about the Project. Landlord specifically excepts
        and reserves to itself the use of any roofs, the exterior portions of
        the Premises, all rights to and the land and improvements below the
        improved floor level of the Premises, the improvements and air rights
        above the Premises and the improvements and air rights located outside
        the demising walls of the Premises, and such areas within the Premises
        as are required for installation of utility lines and other
        installations required to serve any occupants of the Building and the
        right to maintain and repair the same, and no rights with respect
        thereto are conferred upon Tenant unless otherwise specifically provided
        herein.

               Q.   Consents. Except as otherwise expressly set forth herein,
                    --------
        wherever the consent or approval of either Landlord or Tenant is
        required by the provisions of this Lease, such party shall not
        unreasonably withhold or delay such consent or approval.

               R.   Landlord's Agents. Any rights reserved or granted to
                    -----------------
        Landlord hereunder may be exercised by Landlord or any of its agents,
        employees, contractors or designees.

               S.   Terms "Landlord" and "Tenant". The words "Landlord" and
                    -----------------------------
        "Tenant" whenever used in this Lease shall be construed to mean the
        plural where necessary, and the necessary grammatical changes required
        to make the provisions hereof apply either to entities or

                                     -37-
<PAGE>

        individuals, or men or women, shall in all cases be assumed as though in
        each case fully expressed.

               T.   Rent Not Based on Income. It is agreed by Landlord and
                    ------------------------
        Tenant that no rental or other payment for the use, occupancy or
        utilization of the Premises demised hereunder shall be, or is, based in
        whole or in part on the net income or profits derived by any person from
        the Building or the Premises so leased, used, occupied, or utilized, and
        Tenant further agrees that it will not enter into any sublease, license,
        concession or other agreements for any use, occupancy or utilization of
        the Premises which provides for a rental or other payment for such use,
        occupancy or utilization based in whole or in part on the net income or
        profits derived by any person from the Premises so leased, used,
        occupied or utilized.

               U.   No Recording by Tenant.  Tenant shall not record or file in
                    ----------------------
        any public records this Lease or any portion thereof.

               V.   Blue Cross Association, etc. Tenant is not granted by this
                    ---------------------------
        Lease and shall not be entitled to have any exclusive rights in the
        Building other than the rights of its occupancy. Tenant further agrees
        that it will not use its space in the Building in any way which could
        cause any likelihood of confusion with Blue Cross Association (BCA) or
        Blue Shield Association (BSA) or their services, or other harm to BCA or
        BSA by reason of its name. For purposes of this paragraph only, the term
        BCA or BSA includes BCA, BSA, Health Service Incorporated (HSI) or
        Medical Indemnity of America, Inc. (MIA) or the successors of any of
        them or any other entity or organization which shall be in any way
        affiliated with or related to BCA, BSA (or any member Plan of either),
        HSI or MIA, and which has as one of its major purposes a function
        similar or related to those of the aforesaid organizations (for the
        purposes of this Lease, such affiliation or relation may be legal,
        equitable or functional) which includes in its legal or trade name the
        terms "Blue", "Shield", "Cross", or any similar term if they are tenants
        or subtenants in the Building.

               26.  UNRELATED BUSINESS INCOME.

               A.   Landlord shall have the right at any time and from time to
        time to unilaterally amend the provisions of this Lease, if Landlord is
        advised by its counsel that all or any portion of the monies paid by
        Tenant to Landlord hereunder are, or may be deemed to be, unrelated
        business income within the meaning of the United States Internal Revenue
        Code or regulations issued thereunder, and Tenant agrees that it will
        execute all documents or instruments necessary to effect such amendment
        or amendments, provided that no such amendment shall result in Tenant
        having to pay in the aggregate more money on account of its occupancy of
        the Premises under the terms of this Lease, as so amended, and provided
        further that no such amendment shall result in Tenant receiving fewer
        services than it is presently entitled to receive under this Lease.

               B.   Any services which Landlord is required to furnish pursuant
        to the provisions of this Lease may, at Landlord's option, be furnished
        from time to time, in whole or in part, by employees of Landlord or the
        building manager of the Project or its employees or by one or more third
        persons hired by Landlord or the building manager of the Project. Tenant
        agrees that upon Landlord's written request it will enter into direct
        agreements with the building manager of the Project or other parties
        designated by Landlord for

                                     -38-
<PAGE>

        the furnishing of any such services required to be furnished by Landlord
        hereunder, in form and content approved by Landlord, provided however
        that no such contract shall result in Tenant having to pay in the
        aggregate more money on account of its occupancy of the Premises under
        the terms of this Lease, and provided further that no such contract
        shall result in Tenant receiving fewer services or services of a lesser
        quality than it is presently entitled to receive under this Lease.

               27.  HAZARDOUS MATERIALS.  Tenant shall not (either with or
                    -------------------
        without negligence) cause or permit the escape, disposal or release of
        any biologically or chemically active or other hazardous substances, or
        materials. Tenant shall not allow the storage or use of such substances
        or materials in any manner not sanctioned by law or by the highest
        standards prevailing in the industry for the storage and use of such
        substances or materials, nor allow to be brought into the Project any
        such materials or substances except to use in the ordinary course of
        Tenant's business, and then only after written notice is given to
        Landlord of the identity of such substances or materials. 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., the
        Resource Conservation and Recovery Act, as amended, 42 U.S.C. Section
        6901 et seq., any applicable state or local laws and the regulations
        adopted under these acts. If any present or future lender or
        governmental agency shall ever require testing to ascertain whether or
        not there has been any release of hazardous materials, then the
        reasonable costs thereof shall be reimbursed by Tenant to Landlord upon
        demand as Additional Rent hereunder if such requirement applies to the
        Premises. In addition, Tenant shall execute affidavits, representations
        and the like from time to time at Landlord's request concerning Tenant's
        best knowledge and belief regarding the presence of hazardous substances
        or materials on the Premises. In all events, Tenant shall indemnify
        Landlord in the manner elsewhere provided in this lease from any release
        or hazardous materials on the Premises occurring while Tenant is in
        possession, or elsewhere if caused by Tenant or persons acting under
        Tenant. The within covenants shall survive the expiration or earlier
        termination of the Lease Term.

               28.  EXCULPATORY PROVISIONS. It is expressly understood and
                    ----------------------
        agreed by and between the parties hereto, anything herein to the
        contrary notwithstanding, that each and all of the representations,
        warranties, covenants, undertakings and agreements herein made on the
        part of any Landlord while in form purporting to be the representations,
        warranties, covenants, undertakings and agreements of such Landlord are
        nevertheless each and every one of them made and intended, not as
        personal representations, warranties, covenants, undertakings and
        agreements by such Landlord, or for the purpose or with the intention of
        binding such Landlord personally, but are made and intended for the
        purpose only of subjecting such Landlord's interest in the Premises and
        the Project to the terms of this Lease and for no other purpose
        whatsoever, and in case of default hereunder by such Landlord (or
        default through, under or by any of the beneficiaries of any Landlord
        which is a land trust, or any of the agents, servants, employees or
        representatives of such Landlord or said beneficiaries), Tenant shall
        look solely to the interests of such Landlord in the Premises and the
        Project; that no Landlord nor any of the beneficiaries of any Landlord
        which is a land trust shall have any personal liability to pay any
        indebtedness

                                     -39-
<PAGE>

        accruing hereunder or to perform any covenant, either express or
        implied, herein contained and no liability or duty shall rest upon any
        Landlord which is a land trust to sequester the trust estate or the
        rents, issues and profits arising therefrom, or the proceeds arising
        from any sale or other disposition thereof; that no personal liability
        or personal responsibility of any sort is assumed by, nor shall at any
        time be asserted or enforceable against, any Landlord, or against any of
        the beneficiaries of any Landlord which is a land trust, on account of
        this Lease or on account of any representation, warranty, covenant,
        undertaking or agreement of Landlord in this Lease contained, either
        express or implied, all such personal liability, if any, being expressly
        waived and released by Tenant and by all persons claiming by, through or
        under Tenant; that this Lease, if executed by any Landlord which is a
        land trust, is executed and delivered solely in the exercise of the
        powers conferred upon it as such Trustee; and that as to any partnership
        which is a Landlord or the beneficiary of a Landlord which is a land
        trust, a deficit capital account of any partner of such partnership
        shall not be deemed to be an asset or property of such partnership.

               29.  RIGHT OF FIRST OFFER. Subject to Section 29B below, during
                    --------------------
        the Term of this Lease, Tenant shall have and is hereby granted a right
        of first offer on the entire 8th floor of the Building, comprising
        approximately 24,615 rentable square feet (the "ROFO Space"), which
        right shall be exercised in accordance with the procedures set forth in
        Section 29A below.

               A.   If at any time during the Term of this Lease the ROFO Space
        becomes available for lease, Landlord shall give written notice thereof
        to Tenant (the "Landlord's ROFO Notice"). Landlord's ROFO Notice may be
        given at any time up to sixteen (16) months in advance of such
        availability and shall contain the terms upon which Landlord intends to
        offer the ROFO Space for lease to the market. Tenant shall notify
        Landlord within thirty (30) days of receipt of Landlord's ROFO Notice
        whether it desires to lease the ROFO Space on the terms set forth in
        Landlord's ROFO Notice. Tenant's failure to notify Landlord within said
        30-day period shall be deemed a refusal by Tenant. After any such
        refusal or deemed refusal, Tenant shall have no further rights to the
        ROFO Space and Landlord shall be free to lease such space to any person
        or entity for any term. If Tenant exercises its right of first offer
        with respect to the ROFO Space, such space shall be added to the
        Premises for the remaining Term of the Lease on (a) all the terms,
        covenants and conditions specified in the Landlord's ROFO Notice, and
        (b) the terms, covenants and conditions of this Lease to the extent that
        such terms, covenants and conditions of this Lease do not conflict with
        the terms, covenants and conditions specified in the Landlord's ROFO
        Notice. The ROFO Space so added to the Premises pursuant to this Section
        29 shall become a part of the Premises for all purposes of this Lease,
        and any reference in this Lease to the term "Premises" shall be deemed
        to refer to and include the ROFO Space, except as expressly provided
        otherwise in this Lease.

               B.   Tenant's right to exercise its right of first offer with
        respect to the ROFO Space pursuant to this Section 29 is subject to the
        following conditions: (i) that on the date that Tenant delivers its
        binding written notice of its election to exercise its right of first
        offer, Tenant is not in default under any of the terms, covenants or
        conditions of the Lease, and an unmatured event of default has not
        occurred and is not continuing; and (ii) that Tenant shall not have
        assigned the Lease or sublet any portion of the

                                     -40-
<PAGE>

        Premises at any time during the period commencing with the date that
        Tenant delivers its binding written notice to Landlord of its exercise
        of its right of first offer and ending on the date on which the ROFO
        Space is available to be added to the Premises, or at any time prior to
        such period, if such assignment or sublease extends into such period.

               C.   Promptly after Tenant's exercise of its right of first offer
        pursuant to this Section 29, Landlord shall prepare an amendment to the
        Lease to reflect changes in the size of the Premises, Base Rent,
        Tenant's Proportionate Share and any other appropriate terms, due to the
        addition of the ROFO Space. Tenant shall execute and return such an
        amendment to the Lease within fifteen (15) days after its submission to
        Tenant.

               30.  PARKING. Landlord shall provide Tenant with two reserved
        parking spaces in the Building parking lot. Such parking spaces shall be
        provided at Landlord's current rates for parking.

                                     -41-


<PAGE>

        IN WITNESS WHEREOF, the parties hereto have executed this Lease on the
date first above written.

                                        LANDLORD:

                                        TEACHERS INSURANCE AND ANNUITY
                                        ASSOCIATION OF AMERICA, a New
                                        York Corporation

                                        By:__________________________________
                                        Print Name:__________________________
                                        Title:_______________________________

                                        TENANT:

                                        OPEN PORT TECHNOLOGY, INC., an
                                        Illinois corporation

                                        By: /s/ Randy Storch
                                           ----------------------------------
                                        Print Name: Randy Storch
                                                   --------------------------
                                        Title:      President
                                              -------------------------------

                                     -42-
<PAGE>

                                                                      APPENDIX A

                          [PLAN APPEARS HERE]
<PAGE>

                                  APPENDIX B

                               CLEANING SCHEDULE

         Landlord shall furnish janitorial service as described below:

                                     DAILY
                                     -----


     Sweep, dry mop (using treated mops), or vacuum all floor areas (moving
light furniture) of resilient wood or carpet, remove matter such as gum and tar
which had adhered to the floor.

     Empty and damp wipe all ashtrays and waste baskets and remove all trash.

     Dust all horizontal surfaces with treated dust cloth, including furniture,
files, equipment, blinds, and louvers that can be reached without a ladder.

     Damp wipe all telephones, including dials and crevices.

     Spot wash to remove smudges, marks and fingerprints from such areas as
walls, equipment, doors, partitions and light switches within reach.

     Wash and disinfect water fountains and water coolers.

     Damp mop all non-resilient floors such as concrete, terrazzo and ceramic
tile.

     Empty all waste containers.

     Dust and rub down elevator doors, walls, and metal work in elevator cabs.

                                 TOILET ROOMS
                                 ------------

     Clean mirrors, soap dispensers, shelves, wash basins, exposed plumbing,
dispenser and disposal container exteriors using detergent disinfectant and
water. Damp wipe all ledges, toilet stalls and doors, spot clean light switches,
doors and walls.

     Clean toilets and urinals with detergent disinfectant, beginning with seats
and working down. Pour one ounce of bowl cleaner into urinal after cleaning and
do not flush.

     Furnish and refill all soap, toilet, sanitary napkin and towel dispensers.

     Clean all baseboards.

     Damp mop floors using detergent disinfectant.

                                    WEEKLY
                                    ------

     Wash all directory board, display, entry door and side light glass, as
necessary.

     Spot clean carpet stains.


                                  APPENDIX B
                                  Page 1 of 2
<PAGE>

     Spot wash interior partition glass and door glass to remove smudge marks,
and all smudge marks and finger marks from doors, partitions, woodwork, window
ledges and window mullions.

                                    MONTHLY
                                    -------

     Sweep stairwells and landings.

     Wash all uncarpeted areas.

     High dust all horizontal and vertical surfaces not reached in nightly
cleaning, such as pipes, light fixtures, door frames, picture frames and other
wall hangings.

                                   QUARTERLY
                                   ---------

     Vacuum all ceilings and wall air supply and exhaust diffusers or grills.

     Wash all stairwell landings and treads.

     Exterior windows of the building will be cleaned, weather permitting.

     All tile areas to be scrubbed, waxed and buffed.


                                  APPENDIX B
                                  Page 2 of 2
<PAGE>

                                     APPENDIX C
                               RULES AND REGULATIONS

     1.   Tenant shall not place anything, or allow anything to be placed near
the glass of any window, door, partition or wall which may, in Landlord's
judgment, appear unsightly from outside of the Project.

     2.   The Project directory shall be available to Tenant solely to display
names and their location in the Project, which display shall be as directed by
Landlord.

     3.   The sidewalks, halls, passages, exits, entrances, elevators and
stairways shall not be obstructed by Tenant or used by Tenant for any purposes
other than for ingress to and egress from the Premises. Tenant shall lend its
full cooperation to keep such areas free from all obstruction and in a clean and
sightly condition and shall move all supplies, furniture and equipment as soon
as received directly to the Premises and move all such items and waste, being
taken from the Premises (other than waste customarily removed by employees of
the Building) directly to the shipping platform at or about the time arranged
for removal therefrom. The halls, passages, exits, entrances, elevators,
stairways, balconies and roof are not for the use of the general public and
Landlord shall, in all cases, retain the right to control and prevent access
thereto by all persons whose presence in the judgment of Landlord, reasonably
exercised, shall be prejudicial to the safety, character, reputation and
interests of the Project. Neither Tenant nor any employee or invitee of Tenant
shall go upon the roof of the Project.

     4.   The toilet rooms, urinals, wash bowls and other apparatuses shall not
be used for any purposes other than that for which they were constructed, and no
foreign substance of any kind whatsoever shall be thrown therein, and to the
extent caused by Tenant or its employees or invitees, the expense of any
breakage, stoppage or damage resulting from the violation of this rule shall be
borne by Tenant.

     5.   Tenant shall not cause any unnecessary janitorial labor or services by
reason of Tenant's carelessness or indifference in the preservation of good
order and cleanliness.

     6.   Tenant shall not install or operate any refrigerating, heating or air
conditioning apparatus or carry on any mechanical business without the prior
written consent of Landlord; use the Premises for housing, lodging or sleeping
purposes; or permit preparation or warming of food in the Premises (warming of
coffee and individual meals with employees and guests excepted). Tenant shall
not occupy or use the Premises or permit the Premises to be occupied or used for
any purpose, act or thing which is in violation of any public law, ordinance or
governmental regulation or which may be dangerous to persons or property.

     7.   Tenant shall not bring upon, use or keep in the Premises or the
Project any kerosene, gasoline or inflammable or combustible fluid or material,
or any other articles deemed hazardous to persons or property, or use any method
of heating or air conditioning other than that supplied by Landlord.

     8.   Landlord shall have sole power to direct electricians to where and how
telephone and other wires are to be introduced. No

                                  APPENDIX C
                                  Page 1 of 4
<PAGE>

boring or cutting for wires is to be allowed without the consent of Landlord.
The location of telephones, call boxes and other office equipment affixed to the
Premises shall be subject to the approval of Landlord.

     9.   No additional locks shall be placed upon any doors, windows or
transoms in or to the Premises. Tenant shall not change existing locks or the
mechanism thereof. Upon termination of the lease, Tenant shall deliver to
Landlord all keys and passes for offices, rooms, parking lot and toilet rooms
which shall have been furnished Tenant, and shall make known to Landlord the
combination of all locks there remaining in the Premises. In the event of the
loss of keys so furnished, Tenant shall pay Landlord therefor. Tenant shall not
make, or cause to be made, any such keys and shall order all such keys solely
from Landlord and shall pay Landlord for any keys in addition to the two sets of
keys originally furnished by Landlord for each lock.

     10.  Tenant shall not install linoleum, tile, carpet or other floor
covering so that the same shall be affixed to the floor of the Premises in any
manner except as approved by Landlord.

     11.  No furniture, packages, supplies, equipment or merchandise will be
received in the Project or carried up or down in the freight elevator, except
between such hours and in such freight elevator as shall be designated by
Landlord. Tenant shall not take or permit to be taken in or out of other
entrances of the Building or take or permit on other elevators, any item
normally taken in or out through the trucking concourse or service doors or in
or on freight elevators.

     12.  Tenant shall cause all doors to the Premises to be closed and securely
locked and shall turn off all utilities, lights and machines, before leaving the
Project at the end of the day.

     13.  Without the prior written consent of Landlord, Tenant shall not use
the name of the Project or any picture of the Project in connection with, or in
promoting or advertising the business of, Tenant, except Tenant may use the
address of the Project as the address of its business.

     14.  Tenant recognizes that the Blue Cross Association and the Blue Shield
Association and other entities associated with them have the right to use the
name of the Building and pictures or illustrations thereof, and that no other
tenant shall in advertising or in other publicity use the name of the Building
or pictures or illustrations of the Building except with the consent of Blue
Cross Association, Blue Shield Association and Landlord.

     15.  Tenant shall cooperate fully with Landlord to assure the most
effective operation of the Premises' or the Project's heating and air
conditioning, and shall refrain from attempting to adjust any controls, other
than room thermostats installed for Tenant's use. Tenant shall keep corridor
doors closed.

     16.  Tenant assumes full responsibility for protecting the Premises from
theft, robbery and pilferage, which may arise from a cause other than Landlord's
negligence, which includes keeping doors locked and other means of entry to the
Premises closed and secured.

     17.  Peddlers, solicitors and beggars shall be reported to the office of
the Project or as Landlord otherwise requests.

                                  APPENDIX C
                                 Page 2 of 4
<PAGE>

     18.  Tenant shall not advertise the business, profession or activities of
Tenant conducted in the Project in any manner which violates the letter or
spirit of any code of ethics adopted by any recognized association or
organization pertaining to such business, profession or activities.

     19.  No bicycle or other vehicle and no animals or pets shall be allowed in
the Premises, halls, freight docks, or any other parts of the Building except
that blind persons may be accompanied by "seeing eye" dogs. Tenant shall not
make or permit any noise, vibration or odor to emanate from the Premises, or do
anything therein tending to create, or maintain, a nuisance, or do any act
tending to injure the reputation of the Building.

     20.  Tenant acknowledges that Building security problems may occur which
may require the employment of extreme security measures in the day-to-day
operation of the Project.

     Accordingly:

          (a)  Landlord may, at any time, or from time to time, or for regularly
     scheduled time periods, as deemed advisable by Landlord and/or its agents,
     in their sole discretion, require that persons entering or leaving the
     Project or the Property identify themselves to watchmen or other employees
     designated by Landlord, by registration, identification or otherwise.

          (b)  Tenant agrees that it and its employees will cooperate fully with
     Project employees in the implementation of any and all security procedures.

          (c)  Such security measures shall be the sole responsibility of
     Landlord, and Tenant shall have no liability for any action taken by
     Landlord in connection therewith.

     21.  Tenant shall not do or permit the manufacture, sale, purchase, use or
gift of any fermented, intoxicating or alcoholic beverages without obtaining
written consent of Landlord.

     22.  Tenant shall not disturb the quiet enjoyment of any other tenant.

     23.  Tenant shall not provide any janitorial services or cleaning without
Landlord's written consent and then only subject to supervision of Landlord and
at Tenant's sole responsibility and by janitor or cleaning contractor or
employees at all times satisfactory to Landlord.

     24.  Landlord may retain a pass key to the Premises and be allowed
admittance thereto at all times to enable its representatives to examine the
Premises from time to time and, upon reasonable prior notice to Tenant when
practicable, to exhibit the same, and during the last twelve (12) months of the
Term, Landlord may place and keep on the windows and doors of the Premises at
any time signs advertising the Premises for rent.

     25.  No equipment, mechanical ventilators, awnings, special shades or other
forms of window covering shall be permitted either inside or outside the windows
of the Premises without the prior written consent of Landlord, and then only at
the expense and risk

                                  APPENDIX C
                                 Page 3 of 4
<PAGE>

of Tenant, and they shall be of such shape, color, material, quality, design and
make as may be approved by Landlord.

     26.  Tenant shall not during the term of this Lease canvas or solicit other
tenants of the Building for any purpose.

     27.  Tenant shall not install or operate any phonograph, musical or sound
producing instrument or device, radio receiver or transmitter, TV receiver or
transmitter, or similar device in the Building, nor install or operate any
antenna, aerial, wires or other equipment inside or outside the Building, nor
operate any electrical device from which may emanate electrical waves which may
interfere with or impair radio or television broadcasting or reception from or
in the Building or elsewhere, without in each instance the prior written
approval of Landlord. The use thereof, if permitted, shall be subject to control
by Landlord to the end that others shall not be disturbed.

     28.  Tenant shall promptly remove all rubbish and waste from the Premises.

     29.  Tenant shall not exhibit, sell or offer for sale, rent or exchange in
the Premises or at the Project any article, thing or service except those
ordinarily embraced within the use of the Premises specified in Section 6 of
this Lease, without the prior written consent of Landlord.

     30.  Tenant shall list all furniture, equipment and similar articles Tenant
desires to remove from the Premises or the Building and deliver a copy of such
list to Landlord and procure a removal permit from the Office of the Building
authorizing Building employees to permit such articles to be removed.

     31.  Tenant shall not overload any floors in the Premises or any public
corridors or elevators in the Building.

     32.  Tenant shall not do any painting in the Premises, or mark, paint, cut
or drill into, drive nails or screws into, or in any way deface any part of the
Premises or the Building, outside or inside, without the prior written consent
of Landlord.

     33.  Whenever Landlord's consent, approval or satisfaction is required
under these Rules, then unless otherwise stated, any such consent, approval or
satisfaction must be obtained in advance, such consent or approval may be
granted or withheld in Landlord's sole discretion, and Landlord's satisfaction
shall be determined in its sole judgment.

     34.  Tenant and its employees shall cooperate in all fire drills conducted
by Landlord in the Building.

                                  APPENDIX C
                                  Page 4 of 4
<PAGE>

                                  APPENDIX D

                             INTENTIONALLY OMITTED

                                  APPENDIX D
                                  Page 1 of 5
<PAGE>

                            EXHIBIT A to APPENDIX D

                             INTENTIONALLY OMITTED


                            EXHIBIT A of APPENDIX D
                                  Page 1 of 4
<PAGE>

                                  APPENDIX E

                   MORTGAGES CURRENTLY AFFECTING THE PROJECT
                   -----------------------------------------

     NONE.

                                  APPENDIX E
                                  Page 1 of 1

<PAGE>

                                  APPENDIX F

                               CONSTRUCTION BID
                               ----------------

     SEE ATTACHED

                                  APPENDIX E
                                  Page 1 of 1