Document:

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                                                                   EXHIBIT 10.16

                              SECOND AMENDMENT TO
                    OPTION AGREEMENT AND ESCROW INSTRUCTIONS

        This SECOND AMENDMENT TO OPTION AGREEMENT AND ESCROW INSTRUCTIONS
("AMENDMENT") is made and effective as of July 18, 2001 ("EFFECTIVE DATE"), by
DIVERSIFIED EASTGATE VENTURE, an Illinois general partnership ("SELLER"), and
ILLUMINA, INC., a Delaware corporation ("BUYER"), with reference to the facts
set forth below.

                                R E C I T A L S:

        A. Pursuant to that certain Option Agreement and Escrow Instructions
dated July 6, 2000, as amended by that certain First Amendment to Option
Agreement and Escrow Instructions dated May 25, 2001 ("FIRST AMENDMENT")
(collectively, "OPTION AGREEMENT"), Seller granted to Buyer an option ("OPTION")
to purchase certain real property located in the County of San Diego,
California, as more particularly described therein ("PROPERTY"). On or about
November 30, 2000, Buyer exercised its Option to purchase the Property.

        B. Seller and Buyer have also entered into that certain Eastgate Pointe
Lease dated July 6, 2000 ("LEASE") whereby Seller, as Landlord, leased the
Property to Buyer, as Tenant.

        C. Pursuant to the First Amendment, the parties agreed to certain
modifications to the Option Agreement and the Lease based upon Buyer's request
for certain additions and modifications to (a) the Project Plans and the Project
Work under the Option Agreement, and (b) the Tenant Improvement Plans and the
Tenant Improvements under the Lease. As a result of these modifications, the
parties acknowledge that Buyer will not be in a position to close Escrow on or
before the outside Closing Date of August 1, 2001. Accordingly, the parties
desire to modify the Option Agreement to extend the Close of Escrow until
October 1, 2001, on the terms and conditions set forth herein.

        D. In connection with the extension of the Close of Escrow, the parties
also desire to amend the Option Agreement to provide for certain modifications
to the economic terms of the transaction, as set forth on EXHIBIT "A" attached
hereto and incorporated herein. The parties agree that such modifications shall
be made on the terms and conditions set forth herein.

        NOW THEREFORE, in consideration of the foregoing recitals, and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as set forth below.

        1. Section 1.3 -- Option Deposit. The third sentence of Section 1.3 of
the Option Agreement shall be deleted and replaced with the following:

        "The Option Deposit, together with interest calculated thereon at the
        rate of nine percent (9%) per annum (calculated from the date of such
        deposit until August 1, 2001) shall be applied to the Purchase Price in
        the event that Buyer exercises the Option pursuant to Section 1.5
        herein."
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        2. Section 1.5 - Exercise Deposit. Section 1.5 of the Agreement shall be
modified to require Buyer to deliver to Seller an additional Exercise Deposit
("ADDITIONAL EXERCISE DEPOSIT") in the amount of Two Million Six Hundred
Seventy-Eight Thousand Eight Hundred Fifty-Six Dollars ($2,678,856). Buyer shall
deliver the Additional Exercise Deposit directly to Seller, in immediately
available funds, on or before August 1, 2001. Hereafter, the term "EXERCISE
DEPOSIT" shall refer collectively to original Exercise Deposit previously
delivered by Buyer and the Additional Exercise Deposit. The parties acknowledge
that the calculation of the Additional Exercise Deposit, as set forth on EXHIBIT
"A", includes a credit against the Purchase Price to Buyer for the payment of
the Security Deposit and the first month's Monthly Base Rent under the Lease.

        3. Section 2.1 -- Purchase Price. The first sentence of Section 2.1 of
the Option Agreement shall be modified to delete subsection (c) and replace it
with the following:

        "(c) the product of nine percent (9%) per annum multiplied by the amount
        of Three Million Four Hundred Fifty Thousand Dollars ($3,450,000) (the
        "INTEREST CASH CONSIDERATION"), which Interest Cash Consideration shall
        be calculated for the period of time between December 1, 2000 and August
        1, 2001, plus"

        4. Section 3.4 - Extension of Closing Date. The last sentence of Section
3.4 of the Agreement shall be deleted and replaced with the following: "Escrow
shall close on or before October 1, 2001 ("CLOSING DATE")".

        5. Section 3.7 -- Proration of Taxes. Section 3.7(a) of the Option
Agreement shall be deleted in its entirety and replaced with the following:

               "(a) Prorations. The following items shall be prorated in Escrow,
        as of August 1, 2001, based on the latest information available to
        Escrow Agent: (i) real property taxes and any bonds and assessments
        which are Permitted Exceptions as described in Section 4.2 and (ii) all
        insurance paid by or due and owing from Seller relating to the Property
        ("PROPERTY INSURANCE"). Seller shall provide copies of all invoices
        relating to the Property Insurance at least one (1) business day prior
        to the Close of Escrow. All prorations shall be made on the basis of a
        30-day month and a 365-day year, unless the parties otherwise agree in
        writing."

        6. Section 3.7(d) -- Reimbursement for Construction Loan Interest.
Section 3.7 of the Option Agreement shall be amended to add the following as
subsection (d):

               "(d) Buyer agrees that it shall reimburse Seller for the cost of
        all interest which accrues for the period from and after August 1, 2001
        until the Close of Escrow ("CONSTRUCTION LOAN INTEREST") under that
        certain loan to Seller by Washington Capital Joint Master Trust Income
        Fund, as evidenced by that certain

                                       -2-

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        Promissory Note in the principal amount of Twenty-Four Million Dollars
        ($24,000,000) and secured by that certain Deed of Trust, Security
        Agreement, Assignment of Rents and Fixture Filing recorded against the
        Property. Buyer shall pay the Construction Loan Interest to Seller
        monthly within ten (10) days after Buyer's receipt of a written request
        from Seller. Notwithstanding anything to the contrary set forth herein,
        the Construction Loan Interest shall be paid in full on or before the
        Close of Escrow."

        7. Amendment. Except as expressly amended or modified by the provisions
and conditions of this Second Amendment, the Option Agreement shall remain in
full force and effect.

        8. Defined Terms. Capitalized Terms which are not otherwise defined
herein shall have the meanings attributed to them in Option Agreement.

        9. Counterparts. This Amendment may be executed in counterparts.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]

                                      -3-

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        IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date set forth above.

        SELLER:                    DIVERSIFIED EASTGATE VENTURE,
                                   an Illinois general partnership

                                   By:  Diversified Eastgate Pointe, LLC,
                                        a California limited liability company,
                                        Its General Partner

                                        By:    /s/ WILLIAM P. TSCHANTZ
                                               --------------------------------
                                               Its:  Manager

                                   By:  GFBP Partners, LLC,
                                        a California limited liability company,
                                        Its General Partner

                                        By:    /s/ WILLIAM P. TSCHANTZ
                                               --------------------------------
                                               Its:  Manager

        BUYER:                     ILLUMINA, INC.,
                                   a Delaware corporation

                                   By:    /s/ TIMOTHY M. KISH
                                          -------------------------------------
                                   Name:  Timothy M. Kish
                                   Title: Vice President & Chief Financial
                                          Officer

                                      -4-

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                                CONSENT OF LENDER

        The undersigned, as "Lender" under that certain Construction Loan
Agreement dated September 26, 2000, hereby consents to the terms and conditions
of the foregoing Second Amendment to Option Agreement and Escrow Instructions.

Date:  July 25, 2001                    WASHINGTON CAPITAL JOINT MASTER
                                        TRUST MORTGAGE INCOME FUND

                                        By: Washington Capital Management, Inc.,
                                            a Washington corporation,
                                            Its Investment Manager

                                           By:    /s/ DONALD R. MAESCHER
                                                  -----------------------------
                                           Name:  Donald R. Maescher
                                           Title: President, California Division

                                      -5-<PAGE>
                                                                   EXHIBIT 10.17

                               THIRD AMENDMENT TO

                    OPTION AGREEMENT AND ESCROW INSTRUCTIONS

        This THIRD AMENDMENT TO OPTION AGREEMENT AND ESCROW INSTRUCTIONS
("AMENDMENT") is made and effective as of September 27, 2001 ("EFFECTIVE DATE"),
by DIVERSIFIED EASTGATE VENTURE, an Illinois general partnership ("SELLER"), and
ILLUMINA, INC., a Delaware corporation ("BUYER"), with reference to the facts
set forth below.

                                R E C I T A L S:

        A. Pursuant to that certain Option Agreement and Escrow Instructions
dated July 6, 2000, as amended by that certain First Amendment to Option
Agreement and Escrow Instructions dated May 25, 2001 ("FIRST AMENDMENT") and
that certain Second Amendment to Option Agreement and Escrow Instructions dated
July 18, 2001 ("SECOND AMENDMENT") (collectively, "OPTION AGREEMENT"), Seller
granted to Buyer an option ("OPTION") to purchase certain real property located
in the County of San Diego, California, as more particularly described therein
("PROPERTY"). On or about November 30, 2000, Buyer exercised its Option to
purchase the Property.

        B. Seller and Buyer have also entered into that certain Eastgate Pointe
Lease dated July 6, 2000, as amended by that certain First Amendment to Eastgate
Pointe Lease dated concurrently herewith (collectively, "LEASE") whereby Seller,
as Landlord, leased the Property to Buyer, as Tenant.

        C. Pursuant to the First Amendment, the parties agreed to certain
modifications to the Option Agreement and the Lease based upon Buyer's request
for certain additions and modifications to (a) the Project Plans and the Project
Work under the Option Agreement, and (b) the Tenant Improvement Plans and the
Tenant Improvements under the Lease.

        D. As a result of the modifications agreed to in the First Amendment,
the parties acknowledged that Buyer would not be in a position to close Escrow
on or before the outside Closing Date of August 1, 2001. Accordingly, the
parties entered into the Second Amendment to extend the Close of Escrow until
October 1, 2001. In connection with the extension of the Close of Escrow, the
parties also amended the Option Agreement to provide for certain modifications
to the economic terms of the transaction, as set forth therein.

        E. The parties now desire to enter into this Amendment to further extend
the Close of Escrow and to memorialize certain additional modifications to the
Option Agreement, on the terms and conditions set forth herein.

        NOW THEREFORE, in consideration of the foregoing recitals, and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as set forth below.

        1. Section 2.1 -- Credit Against Purchase Price. The first sentence of
Section 2.1 of the Option Agreement shall be modified to add the following at
the end of such sentence:

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        ", minus (e) the total amount of Monthly Base Rent (as defined in the
        Lease) paid by Buyer under the Lease prior to the Close of Escrow."

        2. Section 3.4 - Extension of Closing Date. The last sentence of Section
3.4 of the Option Agreement shall be deleted and replaced with the following:
"Escrow shall close on or before January 15, 2002, but in no event earlier than
January 2, 2002 ("CLOSING DATE")".

        3. Payment for Costs Related to Loan Modifications. The parties
acknowledge that Buyer has requested Seller to negotiate certain modifications
to the loan ("Loan") made to Seller by Washington Capital Joint Master Trust
Fund ("Lender"). Such modifications include, without limitation (a) extension of
the "Construction Maturity Date" under the Promissory Note dated September 26,
2000 ("Promissory Note") until on or about January 15, 2002, (b) increase in the
loan principal by an amount equal to Two Million Dollars ($2,000,000) upon
conversion of the construction loan to a permanent loan under the Promissory
Note, and (c) modifications to the interest rate for the "Permanent Loan" under
the Promissory Note (all modifications to be collectively referred to as the
"Loan Modifications"). Buyer agrees that, in consideration of Seller negotiating
the Loan Modifications with Lender and agreeing to be bound by such
modifications as the borrower under the Loan, Buyer shall pay all costs and
expenses incurred in connection with the Loan Modifications. Such costs and
expenses include, without limitation, any and all fees and/or costs imposed by
Lender, appraisal fees, title and escrow fees, recording charges, loan fees and
legal costs incurred by Lender. Notwithstanding the foregoing, Buyer shall not
be obligated to pay to Lender the extension fee imposed by Lender in the amount
of Eighteen Thousand Dollars ($18,000).

        4. Amendment. Except as expressly amended or modified by the provisions
and conditions of this Amendment, the Option Agreement shall remain in full
force and effect.

        5. Defined Terms. Capitalized Terms which are not otherwise defined
herein shall have the meanings attributed to them in Option Agreement.

        6. Counterparts. This Amendment may be executed in counterparts.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]

                                      -2-

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        IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date set forth above.

        SELLER:                  DIVERSIFIED EASTGATE VENTURE,
                                 an Illinois general partnership

                                 By:    Diversified Eastgate Pointe, LLC,
                                        a California limited liability company,
                                        Its General Partner

                                        By:    /s/ WILLIAM P. TSCHANTZ
                                               --------------------------------
                                               Its:  Manager

                                 By:    GFBP Partners, LLC,
                                        a California limited liability company,
                                        Its General Partner

                                        By:    /s/ WILLIAM P. TSCHANTZ
                                               --------------------------------
                                               Its:  Manager

        BUYER:                   ILLUMINA, INC.,
                                 a Delaware corporation

                                 By:    /s/ TIMOTHY M. KISH
                                        ---------------------------------------
                                 Name:  Timothy M. Kish
                                 Title: Vice President & Chief Financial Officer

                                      -3-

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                                CONSENT OF LENDER

        The undersigned, as "Lender" under that certain Construction Loan
Agreement dated September 26, 2000, hereby consents to the terms and conditions
of the foregoing Third Amendment to Option Agreement and Escrow Instructions.

Date:  September 27, 2001            WASHINGTON CAPITAL JOINT MASTER
                                     TRUST MORTGAGE INCOME FUND

                                     By:  Washington Capital Management, Inc.,
                                          a Washington corporation,
                                          Its Investment Manager

                                          By:    /s/ DONALD R. MAESCHER
                                                 ------------------------------
                                          Name:  Donald R. Maescher
                                          Title: President, California Division

                                      -4-

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