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                                                                     EXHIBIT 4.1

                                 AMENDMENT NO. 1
                           TO THE AMENDED AND RESTATED
                          SHAREHOLDER RIGHTS AGREEMENT

         This Amendment No. 1 to the Amended and Restated Shareholder Rights
Agreement (this "Amendment"), dated as of June 27, 2000 is an amendment to the
Amended and Restated Shareholder Rights Agreement, dated as of March 7, 2000
(the "Rights Agreement"), between Mack-Cali Realty Corporation, a Maryland
corporation (the "Company"), and Equiserve Trust Company, N.A., a Delaware
corporation, (the "Rights Agent").

                                    RECITALS

         WHEREAS, the Company proposed to enter into an Agreement and Plan of
Merger (the "Merger Agreement") dated as of the date hereof with Mack-Cali
Realty, L.P., a Delaware limited partnership ("Mack-Cali Partnership"), Prentiss
Property Trust, a Maryland real estate investment trust ("PPT") and Prentiss
Properties Acquisition Partners, L.P., a Delaware limited partnership ("PPAP"),
pursuant to which PPT will merge with and into the Company and PPAP will merge
with and into Mack-Cali Partnership on the terms set forth therein; and

         WHEREAS, pursuant to and in compliance with Section 27 of the Rights
Agreement, the Company and the Rights Agent wish to amend the Rights Agreement
to reflect the foregoing as set forth herein;

         NOW THEREFORE, the parties hereto agree as follows:

         Section 1.  AMENDMENTS.

             (a) Section 1(a) of the Rights Agreement is amended by adding the
         following language to the end of the first sentence thereof:

                  ", or Prentiss Property Trust, a Maryland real estate
                  investment trust ("PPT"), Prentiss Properties Acquisition
                  Partners, L.P., a Delaware limited partnership ("PPAP"), or
                  any of their Affiliates or Associates by virtue of approval,
                  execution or delivery of the Agreement and Plan of Merger, to
                  be entered into as of June 27, 2000, by and among PPT, PPAP,
                  the Company and Mack-Cali Realty, L.P., a Delaware limited
                  partnership, as it may be amended from time to time in
                  accordance with its terms (the "Merger Agreement"), or by
                  virtue of the consummation of any of the transactions
                  contemplated by the Merger Agreement."

             (b) Section 1(m) of the Rights Agreement is amended by adding the
         following sentence at the end thereof:

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                  "Notwithstanding the foregoing or anything in this Rights
                  Agreement to the contrary, a Distribution Date shall not be
                  deemed to have occurred by virtue of the approval, execution
                  or delivery of the Merger Agreement or by virtue of the
                  consummation of the transactions contemplated by the Merger
                  Agreement."

            (c) Section 1(gg) of the Rights Agreement is amended by adding the
         following sentence at the end thereof:

                  "Notwithstanding the foregoing or anything in this Rights
                  Agreement to the contrary, a Triggering Event shall not be
                  deemed to have occurred by virtue of the approval, execution
                  or delivery of the Merger Agreement or by virtue of the
                  consummation of the transactions contemplated by the Merger
                  Agreement."

          (d) SECTION 11(A)(ii) of the Rights Agreement is amended by adding the
         following sentence at the end thereof:


                  "Notwithstanding the foregoing or anything in this Rights
                  Agreement to the contrary, this section 11(a) shall not apply
                  to the approval, execution and delivery of the Merger
                  Agreement or the consummation of the transactions contemplated
                  thereby."

            (e) Section 13 of the Rights Agreement is amended by adding the
         following sentence at the end thereof:

                  "Notwithstanding the foregoing, this Section 13 shall not
                  apply to the Merger Agreement or the transactions contemplated
                  thereby."

         Section 2. EFFECTIVENESS. This Amendment shall become effective as of,
and immediately prior to, the execution and delivery of the Merger Agreement.
Except as set forth in Section 1 hereof, the terms and provisions of the Rights
Agreement remain in full force and effect and are hereby ratified and confirmed.

         Section 3. AUTHORITY. Each party represents that such party has full
power and authority to enter into this Amendment and that this Amendment
constitutes a legal, valid and binding obligation of such party, enforceable
against such party in accordance with its terms.

          Section 4. GOVERNING LAW. This Amendment shall be deemed to be a
contract made under the laws of the State of Maryland and for all purposes shall
be governed by and construed in accordance with the laws of such State
applicable to contracts to be made and performed within such State.


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          Section 5. COUNTERPARTS. This Amendment may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all of which
shall constitute one and the same.

                   [Remaining page intentionally left blank.]


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         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and attested, all as of the day and year first above written.

Attest:                                MACK-CALI REALTY CORPORATION



By: /s/ Roger W. Thomas                By: /s/ Mitchell E. Hersh
   ---------------------------            ----------------------------------
   Name: Roger W. Thomas                  Name: Mitchell E. Hersh
   Title: Executive Vice President,       Title: Chief Executive Officer
          General Counsel and
          Secretary


Attest:                                EQUISERVE TRUST COMPANY, N.A



By: /s/ Mark Gherzo                    By: /s/ Michael S. Duncan
   ---------------------------            ----------------------------------
   Name: Mark Gherzo                      Name: Michael S. Duncan
   Title: Assistant Vice President,       Title: Director, Corporate Actions
          Corporate Actions

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