Document:

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                                                                   Exhibit 10.16

                      PARTIAL LEASE TERMINATION AGREEMENT
                            AND AMENDMENT TO LEASE

     This Partial Lease Termination Agreement and Amendment to Lease (this
"Agreement") is hereby entered into as of the 28th day of February, 1999 (the
"Early Termination Date") by and between W9/TIB REAL ESTATE LIMITED PARTNERSHIP,
a Delaware limited partnership having an address c/o Archon Group, L.P., 1275 K
Street, N.W., Suite 900, Washington, D.C. 20005 ("Landlord"), and CREATIVE
BIOMOLECULES, INC., a Delaware corporation having an address at 35 South Street,
Hopkinton, Massachusetts 01748 ("Tenant").

     WHEREAS, WRC Properties, Inc. (the "Original Landlord"), as lessor, and
Tenant, as lessee, entered into that certain Standard Form Industrial Lease
dated October 24, 1988 (the "Original Lease"), by which the Original Landlord
leased to Tenant a portion of the building (the "Building") located at and
numbered 35 South Street, Hopkinton, Massachusetts 01748 consisting of
approximately 33,098 square feet of floor area on the first floor of the
Building (the "Original Premises"), as more particularly described in Article 1
of and Exhibit A attached to the Original Lease.

      WHEREAS, the Original Landlord and Tenant entered into that certain
Lease Amendment dated September 17, 1991 (the "First Amendment"), by which the
Original Landlord and Tenant agreed, among other things, to extend the term of
the Original Lease so as to expire on August 31, 1994 and by which the Original
Landlord agreed to lease to Tenant and Tenant agreed to lease from the Original
Landlord an additional 5,970 square feet of floor area on the first floor of the
Building (the "First Amendment Premises").

     WHEREAS, the Original Landlord and Tenant entered into that certain Second
Amendment dated January 28, 1994 (the "Second Amendment"), by which the Original
Landlord and Tenant agreed, among other things, to extend the term of the
Original Lease as amended by the First Amendment so as to expire on June 30,
1995 and by which the Original Landlord agreed to lease to Tenant and Tenant
agreed to lease from the Original Landlord an additional 15,135 square feet of
floor area on the first floor of the Building (the "Second Amendment Premises").

     WHEREAS, the Original Landlord and Tenant entered into that certain Third
Amendment dated September 20, 1994 (the "Third Amendment"), by which the
Original Landlord and Tenant agreed, among other things, to extend the term of
the Original Lease as amended by the First Amendment and the Second Amendment
so as to expire on June 30, 1998.

    WHEREAS, the Original Landlord and Tenant entered into that certain Fourth
Amendment dated April 10, 1994 (the "Fourth Amendment"), by which the Original
Landlord and Tenant agreed, among other things, to extend the term of the
Original Lease as amended by the First Amendment, the Second Amendment and the
Third Amendment so as to expire on June 30, 2001.

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     WHEREAS, the Original Premises, the First Amendment Premises and the Second
Amendment Premises are herein referred to collectively as the "Premises".

     WHEREAS, the Premises consists of approximately 54,203 rentable square feet
of floor area.

     WHEREAS, the Original Lease, as amended by the First Amendment, the Second
Amendment, the Third Amendment and the Fourth Amendment, is hereinafter referred
to as the "Lease".

     WHEREAS, the current term of the Lease expires on June 30, 2001.

     WHEREAS, Landlord has succeeded to the interest of the Original Landlord as
owner of the Building and the land upon which it is located and as lessor under
the Lease.

     WHEREAS, Landlord and Tenant have agreed to early termination of the Lease
with respect to a portion of the Premises consisting of approximately 33,000
rentable square feet of floor area on the first floor of the Building as shown
on Exhibit A attached hereto and incorporated herein by this reference (the
"Terminated Premises") and have agreed to otherwise amend the Lease pursuant to
the terms and provisions of this Agreement.

     WHEREAS, simultaneously with the execution and delivery of this Agreement,
Landlord, as lessor, and Stryker Corporation, a Michigan corporation
("Stryker"), as lessee, have entered into that certain lease (the "Stryker
Lease") dated as of the date hereof, by which Landlord has leased to Stryker the
Terminated Premises.

     NOW, THEREFORE, in consideration of the premises and the mutual agreements
contained herein and in the lease, Landlord and Tenant hereby agree as follows:

     1.   Notwithstanding anything in the Lease to the contrary, the term of the
Lease with respect to the Terminated Premises only shall expire on the Early
Termination Date, subject, however, to Tenant's obligation pursuant to the terms
and provisions of the Lease to pay base rent, Lessee's Pro Rata Share of real
estate taxes, Lessee's Pro Rata Share of operating expenses and Lessee's Pro
Rata Share of insurance expenses, each with respect to the Terminated Premises
for the period on and prior to the Early Termination Date, which obligation
shall survive the expiration of the term of the lease with respect to the
Terminated Premises. Therefore, commencing with the first day following the
Early Termination Date through the expiration or earlier termination of the term
of the Lease, the premises leased by Tenant under the lease as modified by this
Agreement shall be a portion of the first floor of the Building consisting of
approximately 21,203 rentable square feet of floor area as shown on Exhibit B
attached hereto and incorporated herein by this reference (the "Retained
Premises").

     2.   On or prior to the Early Termination Date, Tenant shall deliver to
Landlord the Terminated Premises and surrender the same in their "as is"
condition as of the date hereof except with all of Tenant's equipment, trade
fixtures and other personal property removed therefrom.

                                      -2-
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     3.   Effective as of the first day after the Early Termination Date through
the end of the term of the Lease, the base rent shall be $127,218.00 per year,
payable in equal monthly installments of $10,601.50 (prorated for the month in
which the Early Termination Date occurs if the Early Termination Date is not the
first day of such month).

     4.   Effective as of the first day after the Early Termination Date through
the end of the term of the Lease, "Lessee's Pro Rata Share" (as defined in
Article I and Article XX of the Lease) shall be changed from "78.65%" to
"30.73%".

     5.   Effective from and after the first day following the Early
Termination Date, any references in the Lease to the Terminated Premises shall
be deleted in their entirety such that (i) except with respect to such
obligations which are attributable to periods on or prior to the Early
Termination Date, Landlord shall have no further obligations to Tenant with
respect to the Terminated Premises after the Early Termination Date, and (ii)
except as otherwise expressly provided in paragraph 1 of this Agreement and
except with respect to such obligations which are attributable to periods on or
prior to the Early Termination Date, Tenant shall have no further obligations to
Landlord with respect to the Terminated Premises after the Early Termination
Date.

     6.   Paragraph 3 of the Fourth Amendment is hereby deleted in its entirety.
Landlord and Tenant acknowledge and agree that, notwithstanding anything in the
Lease to the contrary, Tenant shall have no right to extend the term of the
Lease beyond June 30, 2001.

     7.   Paragraph 4 of the Fourth Amendment is hereby deleted in its entirety.
Landlord and Tenant acknowledge and agree that, notwithstanding anything in the
Lease to the contrary, Tenant shall have no rights to expand its leased premises
and no rights of first offer or first refusal with respect to other space in the
Building.

     8.   Pursuant to Article XXI of the Lease, Tenant has deposited with
Landlord a security deposit in the amount $18,479.72 (the "Security Deposit").
Within thirty (30) days after the Early Termination Date, Landlord shall return
to Tenant a portion of the Security Deposit in the amount of $11,250.87, such
that, on and after the return of such amount of $11,250.87, the amount of the
Security Deposit being held by Landlord will be $7,228.85.

     9.   Pursuant to Article XVIII of the Lease, any notice from Tenant to
Landlord required or permitted under the Lease or this Agreement shall be
addressed to Landlord as follows:

          "W9/TIB Real Estate Limited Partnership
          c/o Archon Group, L.P.
          K Street, N.S., Suite 900
          Washington, D.C. 20005"

     10.  Pursuant to Article XVIII of the Lease, any notice from Landlord to
Tenant required or permitted under the Lease or this Agreement shall be
addressed to Tenant as follows:

                                      -3-
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                "Creative Biomolecules, Inc.
                101 Huntington Avenue
                Boston, Massachusetts 02199
                Attention: Cheryl K. Lawton, Esquire"

        11. Notwithstanding anything in the Lease or this Agreement to the
contrary, Tenant shall have (i) the right to sublease and/or permit occupancy of
all or any part of the Retained Premises to Stryker or any Affiliate of Stryker
at any time and from time to time for such periods as Tenant may deem
appropriate and/or (ii) the right to permit Stryker or any Affiliate of Stryker
to access such areas within the Retained Premises as Tenant may deem
appropriate. The foregoing rights of Tenant shall only be effective during such
times as Stryker or any Affiliate of Stryker is occupying all or any material
portion (i.e., ten percent (10%) or more) of the Terminated Premises pursuant to
         ----
the Stryker Lease. As used herein, the phrase "any Affiliate of Stryker" shall
mean any entity which, directly or indirectly, controls, is controlled by or is
under common control with Stryker.

        12. Notwithstanding anything in the Lease or this Agreement to the
contrary, Tenant agrees that (i) there shall not be more than 79 Occupants (as
defined in Article XXV of the Lease) of the Retained Premises at any time and
(ii) discharges from the Retained Premises into the sewer system (as defined in
Article XXV of the Lease) shall not exceed 1,182 gallons per day.

        13. Submission of the Agreement for examination or signature by Tenant
does not constitute a binding agreement, and this Agreement shall not be
effective unless and until execution and delivery thereof by both Landlord and
Tenant.

        14. In all other respects, Landlord and Tenant hereby reaffirm all of
the covenants, agreements, terms, conditions and other provisions of the Lease
except as modified hereby, and the Lease is hereby incorporated in full herein
by this reference. The terms and provisions of this Agreement shall be effective
as of the date first above written, except may otherwise be expressly provided
herein.

                                     -4-

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     IN WITNESS WHEREOF, Landlord and Tenant have executed this Partial Lease
Termination Agreement and Amendment to Lease as a sealed instrument as of the
date first above written.

                                  LANDLORD:

                                  W9/TIB REAL ESTATE LIMITED
                                  PARTNERSHIP

                                  By:  W9/TIB GEN-PAR INC., its General
                                       Partner

                                       By: /s/ Stephen M. Abelman
                                          -------------------------------
                                       Name: Stephen M. Abelman
                                            -----------------------------
                                       Title: Assistant Vice President
                                             ----------------------------

                                  TENANT:

                                  CREATIVE BIOMOLECULES, INC.

                                  By: /s/ Cheryl K. Lawton
                                     -------------------------------
                                  Name: Cheryl K. Lawton
                                       -----------------------------
                                  Title: General Counsel and Vice
                                         President Administration
                                        ----------------------------

                                      -5-

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                                   EXHIBIT A
                                   ---------

                     PLAN SHOWING THE TERMINATED PREMISES
                     ------------------------------------

                       [Floor plan graphic appears here]

                                     -6-

<PAGE>

                                   EXHIBIT B

                      PLAN SHOWING THE RETAINED PREMISES
                      ----------------------------------

                        [Floor plan graphic shown here]

                                     -7-<PAGE>

                                                                     EXHIBIT 4.8

                           SPLITROCK SERVICES, INC.,

                                   as Parent

                                      and

                       HARRIS TRUST COMPANY OF NEW YORK

                                  as Trustee

              __________________________________________________

                         FIRST SUPPLEMENTAL INDENTURE

                         Dated as of November 24, 1999

                                 to INDENTURE

                           Dated as of July 24, 1998

              __________________________________________________

                                 $261,000,000

                         11 3/4% Senior Notes due 2008
<PAGE>

     FIRST SUPPLEMENTAL INDENTURE, dated as of November 24, 1999, by and between
SPLITROCK SERVICES, INC., a Delaware corporation, (the "Company"), and HARRIS
TRUST COMPANY OF NEW YORK (formerly THE BANK OF MONTREAL TRUST COMPANY), a New
York banking corporation trust company, as Trustee (the "Trustee").

                                  WITNESSETH
                                  ----------

     WHEREAS the Company has heretofore executed and delivered to the Trustee an
Indenture dated as of July 24, 1998 (the "Indenture"), providing for the
issuance of an aggregate principal amount of up to $311,000,000 of 11 3/4%
Senior Notes due 2008 (the "Securities");

     WHEREAS, the Company has commenced a solicitation of consents (the "Consent
Solicitation") from the Holders to certain amendments to the Indenture as set
forth in the Consent Solicitation Statement of the Company dated November 9,
1999, as amended by a Supplement thereto, dated November 19, 1999, (the
"Proposed Amendment");

     WHEREAS, pursuant to the Consent Solicitation, the Holders of at least a
majority in aggregate principal amount of the Securities outstanding have
consented (the "Requisite Consents") to the amendments effected by this First
Supplemental Indenture in accordance with the provisions of the Indenture;

     WHEREAS, the First Supplemental Indenture evidences the Proposed Amendment
described in the Consent Solicitation Statement and the Supplement thereto;

     WHEREAS, Section 9.02 of the Indenture provides, among other things, that
with the written consent of Securityholders holding not less than a majority in
principal amount of the Securities then outstanding, the Company may from time
to time amend or supplement the Indenture, subject to certain exceptions
specified in Section 9.02 of the Indenture;

     WHEREAS, on November 9, 1999, the Company mailed or otherwise delivered a
Consent Solicitation Statement to each Holder of record as of November 8, 1999
and a Supplement thereto on November 19, 1999, and has obtained the Requisite
Consents;

     WHEREAS, this First Supplemental Indenture has been duly authorized by all
necessary corporate action on the part of the Company; and

     WHEREAS, the Company has delivered, or caused to be delivered, to the
Trustee, an Officer's Certificate and an Opinion of Counsel meeting the
requirements of Section 11.04 and 11.05 of the Indenture and stating that all
conditions precedent and covenants, if any, provided for in the Indenture
relating to this First Supplemental Indenture have been satisfied.

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, receipt of which is hereby acknowledged, the Subsidiary
Guarantor, the Company, and the Trustee mutually covenant and agree for the
equal and ratable benefit of the holders of the Securities as follows:

                                       1
<PAGE>
                                   ARTICLE I
                                   ---------

                                  Amendments
                                  ----------

     SECTION 1.01.  Amendments to Indenture and the Securities. The amendments
                    ------------------------------------------
set forth in this First Supplemental Indenture shall become operative on the
date that the Company notifies the Trustee in connection with the Consent
Solicitation that the Consents tendered are accepted pursuant to the Consent
Solicitation (the "Consent Date"). If Holders of a majority in aggregate
principal amount of the Securities do not tender Consents (the "Requisite
Consents") for any reason and the Consent Solicitation is not effected, the
amendments set forth herein will not become operative. The Indenture is hereby
amended as follows:

               A.   From and after the Consent Date, Clause (b)(vi) of Section
     4.03 of the Indenture is hereby amended by deleting the words "80% of" just
     before the phrase "(a) the Fair Market Value" therein.

               B.  From and after the Consent Date, the defined term "Purchase
     Money Indebtedness" in Section 1.01 of the Indenture is hereby amended by
     deleting clause (iii) thereof in its entirety and inserting the following
     in its place: "(iii) with respect to any Secured Indebtedness which
     constitutes Purchase Money Indebtedness, the Stated Maturity of such
     Secured Indebtedness shall not exceed the expected depreciable life, as
     determined by the Company, of the Telecommunications Assets securing such
     Secured Indebtedness."

     SECTION 1.02. Successors and Assigns.  This Article I shall be binding upon
                   -----------------------
the Company and shall inure to the benefit of the successors and assigns of the
Trustee and the Holders and, in the event of any transfer or assignment of
rights by any Holder or the Trustee, the rights and privileges conferred upon
that party in the Indenture and this First Supplemental Indenture and in the
Securities shall automatically extend to and be vested in such transferee or
assignee, all subject to the terms and conditions of the Indenture and this
First Supplemental Indenture.

     SECTION 1.03. Modification.  No modification, amendment or waiver of any
                   -------------
provision of this Article 1, nor the consent to any departure by the Company
therefrom, shall in any event be effective unless the same shall be in writing
and signed by the Trustee, and then such waiver or consent shall be effective
only in the specific instance and for the purpose for which given.

                                       2
<PAGE>

                                  ARTICLE II
                                  ----------

                                 Miscellaneous
                                 -------------

     SECTION 2.01.  Ratification of Indenture: Supplemental Indentures Part
                    -------------------------------------------------------
of Indenture.  Except as expressly amended hereby, the Indenture is in all
-------------
respects ratified and confirmed and all the terms, conditions and provisions
thereof shall remain in full force and effect. Upon the execution and delivery
of this First Supplemental Indenture by the Company and the Trustee, this First
Supplemental Indenture shall form a part of the Indenture for all purposes, and
every holder of Securities heretofore or hereafter authenticated and delivered
shall be bound hereby. Any and all references, whether within the Indenture or
in any notice, certificate or other instrument or document, shall be deemed to
include a reference to this First Supplemental Indenture (whether or not made),
unless the context shall otherwise require.

     SECTION 2.02.  Governing Law; Governance, Etc. THIS FIRST SUPPLEMENTAL
                    -------------------------------
INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF
THE STATE OF NEW YORK BUT WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF
CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF ANOTHER
JURISDICTION WOULD BE REQUIRED THEREBY. This First Supplemental Indenture shall
be governed and construed in accordance with the applicable terms and provisions
of the Indenture as amended hereby, which terms and provisions are incorporated
herein by reference, as if this First Supplemental Indenture were the
"Indenture" referred to therein.

     SECTION 2.03.  Trustee Makes No Representation.  The Trustee makes no
                    --------------------------------
representation as to the validity or sufficiency of this First Supplemental
Indenture.

     SECTION 2.04.  Counterparts.  The parties may sign any number of copies of
                    -------------
this First Supplemental Indenture.  Each signed copy shall be an original, but
all of them together represent the same agreement.

     SECTION 2.05.  Effect of Headings.  The Section headings herein are for
                    -------------------
convenience only and shall not effect the construction thereof

     SECTION 2.06.  Terms.  Certain capitalized terms used but not defined
                    ------
herein have the meanings assigned to them in the Indenture.

     SECTION 2.07.  Entire Agreement.  This First Supplemental Indenture,
                    ----------------
together with the Indenture as amended hereby and the Securities, contains the
entire agreement of the parties, and supersedes all other representations,
warranties, agreements and understandings between the parties, oral or
otherwise, with respect to the matters contained herein and therein.

     SECTION 2.08.  Benefits of First Supplemental Indenture. Nothing in
                    ----------------------------------------
this First Supplemental Indenture, the Indenture, or the Securities, express or
implied, shall give to any Person, other than the parties hereto and thereto and
their successors hereunder and thereunder, and the Securityholders, any benefit
of any legal or equitable right, remedy or claim under the Indenture, the First
Supplemental Indenture or the Securities.

                                       3
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this First Supplemental
Indenture to be duly executed as of the date first above written.

                                   SPLITROCK SERVICES, INC.

                                   By_____________________________________
                                   Name:
                                   Title:

                                   HARRIS TRUST COMPANY OF NEW YORK,
                                   as Trustee,

                                   By ____________________________________
                                   Name:
                                   Title:

                                       4

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