Document:

Exhibit 4.1

                                FACE OF SECURITY

            THE NOTE EVIDENCED HEREBY AND THE SHARES OF COMMON STOCK ISSUABLE
UPON THE CONVERSION HEREOF HAVE NOT BEEN REGISTERED UNDER THE U.S. SECURITIES
ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR OTHER SECURITIES LAWS. NONE
OF THIS NOTE, THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION HEREOF OR ANY
INTEREST OR PARTICIPATION HEREIN MAY BE RE-OFFERED, SOLD, ASSIGNED, TRANSFERRED,
PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION
OR UNLESS THE TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT. THE HOLDER OF THIS SECURITY BY ITS
ACCEPTANCE HEREOF (1) REPRESENTS THAT IT IS AN "ACCREDITED INVESTOR" (AS DEFINED
IN REGULATION D UNDER SECURITIES ACT), (2) AGREES THAT IT WILL NOT PRIOR TO (X)
THE DATE WHICH IS TWO YEARS (OR SUCH SHORTER PERIOD OF TIME AS PERMITTED BY RULE
144(K) UNDER THE SECURITIES ACT OR ANY SUCCESSOR PROVISION THEREUNDER) AFTER THE
LATER OF THE ORIGINAL ISSUE DATE HEREOF (OR OF ANY PREDECESSOR OF THIS NOTE) OR
THE LAST DAY ON WHICH VAXGEN, INC. (THE "COMPANY") OR ANY AFFILIATE OF THE
COMPANY WAS THE OWNER OF THIS NOTE (OR ANY PREDECESSOR OF THIS NOTE) AND (Y)
SUCH LATER DATE, IF ANY, AS MAY BE REQUIRED BY APPLICABLE LAW (THE "RESALE
RESTRICTION TERMINATION DATE"), OFFER, SELL OR OTHERWISE TRANSFER THIS NOTE OR
THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION HEREOF EXCEPT (A) TO THE
COMPANY, (B) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED
EFFECTIVE UNDER THE SECURITIES ACT, (C) WHEN AND FOR SO LONG AS THE SECURITIES
ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT, TO A
PERSON IT REASONABLY BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" AS DEFINED IN
RULE 144A UNDER THE SECURITIES ACT THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE
ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE
TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, OR (D) PURSUANT TO ANY OTHER
AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND
(3) AGREES THAT IT WILL GIVE TO EACH PERSON TO WHOM THIS NOTE OR THE SHARES OF
COMMON STOCK ISSUABLE UPON CONVERSION HEREOF ARE TRANSFERRED A NOTICE
SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND; PROVIDED THAT THE COMPANY, THE
TRUSTEE AND THE REGISTRAR SHALL HAVE THE RIGHT PRIOR TO ANY SUCH OFFER, SALE OR
TRANSFER (I) PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY OF AN OPINION OF
COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM AND
(II) IN EACH OF THE FOREGOING CASES, TO REQUIRE THAT A CERTIFICATION OF TRANSFER
IN THE FORM APPEARING ON THE OTHER SIDE OF THE NOTE IS COMPLETED AND DELIVERED
BY THIS TRANSFEROR TO THE TRUSTEE. THIS LEGEND WILL BE REMOVED UPON THE REQUEST
OF THE HOLDER AFTER THE RESALE RESTRICTION TERMINATION DATE.

<PAGE>

            THIS NOTE, ANY SHARES OF COMMON STOCK ISSUABLE UPON THE CONVERSION
HEREOF AND ANY RELATED DOCUMENTATION MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO
TIME TO MODIFY THE RESTRICTIONS ON RESALES AND OTHER TRANSFERS OF THIS NOTE AND
ANY SUCH SHARES TO REFLECT ANY CHANGE IN APPLICABLE LAW OR REGULATION (OR THE
INTERPRETATION THEREOF) OR IN PRACTICES RELATING TO THE RESALE OR TRANSFER OF
RESTRICTED SECURITIES GENERALLY. THE HOLDER OF THIS NOTE AND SUCH SHARES SHALL
BE DEEMED BY THE ACCEPTANCE OF THIS NOTE AND ANY SUCH SHARES TO HAVE AGREED TO
ANY SUCH AMENDMENT OR SUPPLEMENT.

<PAGE>

                                  VAXGEN, INC.

          5 1/2% CONVERTIBLE SENIOR SUBORDINATED NOTE DUE APRIL 1, 2010

No. 1                                                           U.S.$ 300,000.00

CUSIP No. 922390 AA 7
ISIN NUMBER : US922390AA76

VaxGen, Inc., a corporation duly organized and existing under the laws of the
State of Delaware (herein called the "Company," which term includes any
successor Person under the Indenture referred to on the reverse hereof), for
value received, hereby promises to pay to ___________., or registered assigns,
the principal sum of THREE HUNDRED THOUSAND UNITED STATES DOLLARS (U.S.$
300,000.00) (which principal amount may from time to time be increased or
decreased to such other principal amounts (which, taken together with the
principal amounts of all other Outstanding Securities, shall not exceed U.S.
$31,500,000 in the aggregate at any time, on April 1, 2010, unless redeemed,
repurchased or converted on an earlier date, and to pay interest thereon, from
April 5, 2005, or from the most recent Interest Payment Date (as defined below)
to which interest has been paid or duly provided for, semiannually in arrears on
April 1 and October 1 in each year (each, an "Interest Payment Date"),
commencing October 1, 2005, at the rate of 5 1/2% per annum, until the principal
hereof is due, and at the rate then in effect on any overdue principal and
premium, if any, and, to the extent permitted by law, on any overdue interest.
The interest so payable, and punctually paid or duly provided for, on any
Interest Payment Date will, as provided in the Indenture, be paid to the Person
in whose name this Security (or one or more Predecessor Securities) is
registered at the close of business on the Regular Record Date for such
interest, which shall be the March 15 and September 15 (whether or not a
Business Day), as the case may be, next preceding such Interest Payment Date.
Except as otherwise provided in the Indenture, any such interest not so
punctually paid or duly provided for will forthwith cease to be payable to the
Holder on such Regular Record Date and may either be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on a Special Record Date for the payment of such Defaulted
Interest to be fixed by the Company, notice whereof shall be given to Holders of
Registered Securities not less than ten days prior to such Special Record Date,
or be paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Securities may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in the Indenture. Payments of principal shall be made upon the
surrender of this Security at the option of the Holder at the Corporate Trust
Office or at such other office or agency of the Company as may be designated by
it for such purpose in the Borough of Manhattan, The City of New York, in such
coin or currency of the United States of America as at the time of payment shall
be legal tender for t he payment of public and private debts, or at such other
offices or agencies as the Company may designate, by United States Dollar check
drawn on, or wire transfer to, a United States Dollar account (such a wire
transfer to be made only to a Holder of an aggregate principal amount of
Registered Securities in excess of U.S. $2,000,000 and only if such Holder shall
have furnished wire instructions in writing to the Trustee no later than 15 days
prior to the relevant payment date) maintained by the payee. Payment of interest
on this Security may be made by United States Dollar check mailed to the address
of the Person entitled thereto as such address shall appear in the Security
Register or, upon written application

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by the Holder to the Security Registrar setting forth wire instructions not
later than the relevant Record Date, by wire transfer to a United States dollar
account (such a wire transfer to be made only to a Holder of an aggregate
principal amount of Registered Securities in excess of U.S. $2,000,000 and only
if such Holder shall have furnished wire instructions in writing to the Trustee
no later than 15 days prior to the relevant payment date) maintained by the
payee.

            Except as specifically provided herein and in the Indenture, the
Company shall not be required to make any payment with respect to any tax,
assessment or other governmental charge imposed by any government or any
political subdivision or taxing authority thereof or therein.

            Reference is hereby made to the further provisions of this Security
set forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

            Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereof or an Authenticating Agent by the
manual signature of one of their respective authorized signatories, this
Security shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

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            IN WITNESS WHEREOF, the Company has caused this Security to be duly
executed.

                                        VAXGEN, INC.

                                        By: ____________________________________
                                            Name: ______________________________
                                            Title: _____________________________

Dated: April 5, 2005

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            This is one of the Securities referred to in the within-mentioned
Indenture.

U.S. Bank National Association,
as Trustee

By: __________________________________
        Authorized Signatory

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                               REVERSE OF SECURITY

            This Security is one of a duly authorized issue of securities of the
Company designated as its "5 1/2% Convertible Senior Subordinated Notes due
April 1, 2010" (herein called the "Securities"), limited in aggregate principal
amount to U.S. $31,500,000, issued and to be issued under an Indenture, dated as
of April 5, 2005 (herein called the "Indenture"), between the Company and U.S.
Bank National Association, as Trustee (herein called the "Trustee," which term
includes any successor trustee under the Indenture), to which Indenture and all
indentures supplemental thereto reference is hereby made for a statement of the
respective rights, limitations of rights, duties and immunities thereunder of
the Company, the Trustee, the holders of Senior Debt and the Holders of the
Securities and of the terms upon which the Securities are, and are to be,
authenticated and delivered. As provided in the Indenture and subject to certain
limitations set forth therein, Registered Securities are exchangeable for a like
aggregate principal amount of Registered Securities of any authorized
denominations as requested by the Holder surrendering the same upon surrender of
the Registered Security or Registered Securities to be exchanged at the
Corporate Trust Office. The Trustee upon such surrender by the Holder will issue
the new Registered Securities in the requested denominations.

            No sinking fund is provided for the Securities.

            The Securities are subject to redemption at the option of the
Company at any time prior to April 1, 2010 ("Provisional Redemption"), in whole
or in part, upon not less than 30 nor more than 60 days' notice to the Holders
prior to the Redemption Date at a Redemption Price equal to 100% of the
principal amount, together, in each case, with accrued and unpaid interest
(including, Liquidated Damages, if any) to, but excluding, the Redemption Date
plus the Interest Make-Whole Payment; provided, that (a) the Closing Sale Price
of the Common Stock has exceeded 150% of the Conversion Price then in effect for
at least 20 Trading Days within a period of 30 consecutive Trading Days ending
on the Trading Date immediately before the date of mailing of the Redemption
Notice and (2) the Registration Statement covering resale of the Securities and
the Underlying Common Stock (as defined in the Purchase Agreement) is effective
and available for use for the 30 days following the Redemption Day, unless
registration thereof is not required. Upon any Provisional Redemption, the
Company will pay to the Holders cash (except as set forth below) with respect to
the Securities called for Provisional Redemption, including any Security
converted after the date of the notice of Provisional Redemption and before to
the date of the Provisional Redemption. Notwithstanding the foregoing, the
Company may make the Interest Make-Whole Payment in (a) cash, (b) subject to
certain conditions set forth below in the Indenture, Common Stock or Successor
Common Stock or (c) a combination of cash and Common Stock or Successor Common
Stock.

            In the event of a redemption of the Securities, the Company will not
be required (a) to register the transfer or exchange of Registered Securities
for a period of 15 days immediately preceding the date notice is given
identifying the serial numbers of the Securities called for such redemption (it
being understood that the Company will not be required to identify the serial
numbers of Outstanding Securities if all such Securities are called for
redemption) or

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(b) to register the transfer or exchange of any Registered Security, or portion
thereof, called for redemption.

            In any case where the due date for the payment of the principal of,
premium, if any, or interest (including Liquidated Damages, if any) on any
Security or the last day on which a Holder of a Security has a right to convert
his Security shall be, at any Place of Payment or Place of Conversion, as the
case may be, a day on which banking institutions at such Place of Payment or
Place of Conversion are authorized or obligated by law or executive order to
close, then payment of principal, premium, if any, or interest (including
Liquidated Damages, if any) or delivery for conversion of such Security need not
be made on or by such date at such place but may be made on or by the next
succeeding day at such place which is not a day on which banking institutions
are authorized or obligated by law or executive order to close, with the same
force and effect as if made on the date for such payment or the date fixed for
redemption or repurchase, or by such last day for conversion, and no interest
shall accrue on the amount so payable for the period from and after such due
date.

            Subject to and upon compliance with the provisions of the Indenture,
the Holder of this Security is entitled, at its option, at any time following
the original issue date of the Securities and on or before the close of business
on April 1, 2010, or in case this Security or a portion hereof is called for
redemption or the Holder hereof has exercised his right to require the Company
to repurchase this Security or such portion hereof, then in respect of this
Security until and including, but (unless the Company defaults in making the
payment due upon redemption or repurchase, as the case may be) not after, the
close of business on the Business Day immediately preceding the Redemption Date
or the Change in Control Purchase Date, as the case may be, to convert this
Security or any portion of the principal amount hereof that is an integral
multiple of U.S. $1,000 (provided that the unconverted portion of such principal
amount is U.S.$1,000 or any integral multiple of U.S. $1,000 in excess thereof)
into fully paid and nonassessable shares of Common Stock of the Company at an
initial Conversion Rate of 67.7507 shares of Common Stock per $1,000 principal
amount of Securities (or at the current adjusted Conversion Rate if an
adjustment has been made as provided in the Indenture) by surrender of this
Security, duly endorsed or assigned to the Company or in blank and, in case such
surrender shall be made during the period from the close of business on any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date (except if this Security has been called
for redemption on a Redemption Date or is repurchasable on a Change in Control
Purchase Date, with the consequence that the conversion right of such Security
would terminate between such Regular Record Date and the close of business on
such Interest Payment Date), also accompanied by payment in New York Clearing
House or other funds acceptable to the Company of an amount equal to the
interest payable on such Interest Payment Date on the principal amount of this
Security then being converted, and also the conversion notice hereon duly
executed, to the Company at the Corporate Trust Office, or at such other office
or agency of the Company, subject to any laws or regulations applicable thereto
and subject to the right of the Company to terminate the appointment of any
Conversion Agent (as defined below) as may be designated by it for such purpose
in the Borough of Manhattan, The City of New York, or at such other offices or
agencies as the Company may designate (each a "Conversion Agent"),

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provided, further, that in case surrender of this Security for conversion shall
be made during the period from the close of business on any Regular Record Date
next preceding any Interest Payment Date to the opening of business on such
Interest Payment Date and if this Security or portion hereof has been called for
redemption on a Redemption Date or is repurchasable on a Change in Control
Purchase Date, with the consequence that the conversion right of such Security
would terminate between such Regular Record Date and the close of business on
such Interest Payment Date, then the Holder of this Security will be entitled to
receive the interest accruing hereon from the Interest Payment Date next
preceding the date of such conversion to such succeeding Interest Payment Date
and shall not be required to pay such interest upon surrender of this Security
for conversion. Subject to the provisions of the preceding sentence and, in the
case of a conversion after the close of business on the Regular Record Date next
preceding any Interest Payment Date and on or before the close of business on
such Interest Payment Date, to the right of the Holder of this Security (or any
Predecessor Security of record as of such Regular Record Date) to receive the
related installment of interest to the extent and under the circumstances
provided in the Indenture, no cash payment or adjustment is to be made on
conversion for interest accrued hereon from the Interest Payment Date next
preceding the day of conversion, or for dividends on the Common Stock issued on
conversion hereof. The Company shall thereafter deliver to the Holder the fixed
number of shares of Common Stock (together with any cash adjustment or rights or
warrants, as provided in the Indenture) into which this Security is convertible
and such delivery will be deemed to satisfy the Company's obligation to pay the
principal amount of this Security. No fractions of shares or scrip representing
fractions of shares will be issued on conversion, but instead of any fractional
interest (calculated to the nearest 1/100th of a share) the Company shall pay a
cash adjustment as provided in the Indenture. The Conversion Rate is subject to
adjustment as provided in the Indenture. In addition, the Indenture provides
that in case of certain consolidations or mergers to which the Company is a
party or the conveyance, transfer, sale or lease (other than a grant of security
interest) of all or substantially all of the property and assets of the Company,
the Indenture shall be amended, without the consent of any Holders of
Securities, so that this Security, if then Outstanding, will be convertible
thereafter, during the period this Security shall be convertible as specified
above, only into the kind and amount of securities, cash and other property
receivable upon such consolidation, merger, conveyance, transfer, sale or lease
by a holder of the number of shares of Common Stock of the Company into which
this Security could have been converted immediately prior to such consolidation,
merger, conveyance, transfer, sale or lease (assuming such holder of Common
Stock is not a Constituent Person or an Affiliate of a Constituent Person,
failed to exercise any rights of election and received per share the kind and
amount received per share by a plurality of Non-electing Shares). No adjustment
in the Conversion Rate will be made until such adjustment would require an
increase or decrease of at least one percent of such rate, provided that any
adjustment that would otherwise be made will be carried forward and taken into
account in the computation of any subsequent adjustment.

            The Holder of this Security (including any Person that has a
beneficial interest in this Security) and the Common Stock issuable upon
conversion hereof is entitled to the registration rights set forth in a Purchase
Agreement, dated as of March 30, 2005 (the "Purchase

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Agreement"), executed by the Company and the Holder. Pursuant to the Purchase
Agreement, the Company has agreed for the benefit of the Holders from time to
time of Registered Securities and the Common Stock issuable upon conversion
thereof, in each case, that are Registrable Securities, at the Company's
expense, (a) to file with the Commission, as soon as reasonably practicable, but
in no event later than 30 days after the first date the Company becomes current
in its reporting requirements under the Exchange Act, a registration statement
(the "Registration Statement") with respect to resales of the Registrable
Securities, (b) thereafter to use its reasonable best efforts to cause the
Registration Statement to be declared effective by the Commission on or prior to
(1) 90 days following the filing of such Registration Statement if there is no
review of the Registration Statement by the Commission or (2) 120 days following
the filing of such Registration Statement if there is a review of the
Registration Statement by the Commission and (c) prepare and file with the
Commission such amendments and supplements to the Registration Statement and the
prospectus used in connection therewith as may be necessary to keep the
Registration Statement continuously effective until the earlier of (1) the
second anniversary of the issuance of the Securities and (2) such time as all
Registrable Securities held by Holders have been sold pursuant to the
Registration Statement. The Company is required to pay Liquidated Damages to
holders of Registrable Securities for failure to comply with the foregoing
registration obligations, all as more fully set forth in the Purchase Agreement.

            Whenever in this Security there is a reference, in any context, to
the payment of the principal of, premium, if any, or interest on, or in respect
of, any Security such mention shall be deemed to include mention of the payment
of Liquidated Damages payable as described in the Purchase Agreements to the
extent that, in such context, Liquidated Damages are, were or would be payable
in respect of this Security pursuant to the Purchase Agreement, and an express
mention of the payment of Liquidated Damages (if applicable) in any provisions
of this Security shall not be construed as excluding Liquidated Damages in those
provisions of this Security where such express mention is not made. If the
Holder of this Security (including any Person that has a beneficial interest in
this Security) elects to sell this Security pursuant to the Registration
Statement then, by its acceptance hereof, such Holder of this Security agrees to
be bound by the terms of the Purchase Agreements relating to the Registrable
Securities which are the subject of such election.

            If a Change in Control occurs, the Holder of this Security, at the
Holder's option, shall have the right, in accordance with the provisions of the
Indenture, to require the Company to repurchase this Security (or any portion of
the principal amount hereof that is equal to U.S. $1,000 or any greater integral
multiple of U.S. $1,000) for cash at a Change in Control Purchase Price equal to
100% of the principal amount thereof plus interest accrued (including any
Liquidated Damages, if any) to, but excluding, the Change in Control Purchase
Date plus, in certain instances, the Make-Whole Premium. At the option of the
Company, the Change in Control Purchase Price and/or the Make-Whole Premium may
be paid in cash or, subject to the conditions provided in the Indenture, by
delivery of shares of Common Stock or Successor Common Stock or in a combination
of cash and Common Stock or Successor Common Stock, having a fair market value
equal to the Change in Control Purchase Price or Make-Whole Premium (as
applicable). For purposes of this paragraph, (a) the value of Common Stock or
the

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Successor Common Stock to be delivered in respect of the Change in Control
Purchase Price shall be deemed to be equal to 95% of the average of the Closing
Sale Prices per share for the five consecutive Trading Days ending on and
including the third day prior to the Change in Control Purchase Date; provided
that the Change in Control Purchase Price may only be paid in Successor Common
Stock if such common stock is traded on The Nasdaq National Market or other U.S.
national securities exchange and (b) the value of its Common Stock or the
Successor Common Stock to be delivered in respect of the Make-Whole Premium
shall be deemed equal to 95% of the average of the Closing Sale Prices per share
for the ten Trading Day period ending on the Trading Day immediately preceding
the Change in Control Purchase Date. The Company may pay the Make-Whole Premium
in shares of its Common Stock or the Successor Common Stock only if the
information necessary to calculate the Closing Sale Price per share is published
in a daily newspaper of general circulation or by other appropriate means.
Whenever in this Security there is a reference, in any context, to the principal
of any Security as of any time, such reference shall be deemed to include
reference to the Change in Control Purchase Price payable in respect of such
Security to the extent that such Change in Control Purchase Price is, was or
would be so payable at such time, and express mention of the Change in Control
Purchase Price in any provision of this Security shall not be construed as
excluding the Change in Control Purchase Price so payable in those provisions of
this Security when such express mention is not made; provided, however, that,
for the purposes of the paragraph below concerning the consequences of an Event
of Default, such reference shall be deemed to include reference to the Change in
Control Purchase Price only to the extent the Change in Control Purchase Price
is payable in cash.

            In the event of redemption, repurchase or conversion of this
Security in part only, a new Security or Securities for the unredeemed,
unrepurchased or unconverted portion hereof will be issued in the name of the
Holder hereof.

            The indebtedness evidenced by this Security is, to the extent and in
the manner provided in the Indenture, subordinate and subject in right of
payment to the prior payment in full in cash or Cash Equivalents of all Senior
Debt of the Company, and this Security is issued subject to such provisions of
the Indenture with respect thereto. Each Holder of this Security, by accepting
the same,

            (a) agrees to and shall be bound by such provisions,

            (b) authorizes and directs the Trustee on his behalf to take such
action as may be necessary or appropriate to effectuate the subordination so
provided, and

            (c) appoints the Trustee his attorney-in-fact for any and all such
purposes.

            If an Event of Default shall occur and be continuing, the principal
of all the Securities, together with accrued and unpaid interest, if any, to the
date of declaration, may be declared due and payable in the manner and with the
effect provided in the Indenture. Upon payment (i) of the amount of principal so
declared due and payable, together with accrued and

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unpaid interest to the date of declaration, and (ii) of interest on any overdue
principal and, to the extent permitted by applicable law, overdue interest, all
of the Company's obligations in respect of the payment of the principal of and
interest on the Securities shall terminate.

            The Indenture permits, with certain exceptions as therein provided,
the amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities under the Indenture at
any time by the Company and the Trustee with the written consent of the Holders
of a majority in principal amount of the Securities at the time Outstanding. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the Securities at the time Outstanding, on
behalf of the Holders of all the Securities, to waive compliance by the Company
with certain provisions of the Indenture and certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the Holder of
this Security shall be conclusive and binding upon such Holder and upon all
future Holders of this Security and of any Security issued in exchange herefor
or in lieu hereof, whether or not notation of such consent or waiver is made
upon this Security or such other Security.

            As provided in and subject to the provisions of the Indenture, the
Holder of this Security shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default, the Holders of not
less than 25% in principal amount of the Outstanding Securities shall have made
written request to the Trustee to institute proceedings in respect of such Event
of Default as Trustee and furnished the Trustee indemnity reasonably acceptable
to it, the Trustee shall have failed to institute any such proceeding for 60
days after receipt of such notice, request and offer of indemnity, and the
Trustee has not received any direction inconsistent with such written request
from the Holders of a majority of the aggregate principal amount of the
Outstanding Securities during such 60 day period. The foregoing shall not apply
to any suit instituted by the Holder of this Security for the enforcement of any
payment of principal hereof, premium, if any, Liquidated Damages, if any, or
interest hereon on or after the respective due dates expressed herein or for the
enforcement of the right to convert this Security as provided in the Indenture.

            No reference herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of, premium,
if any, Liquidated Damages, if any, and interest on this Security at the times,
places and rate, and in the coin or currency, herein prescribed or to convert
this Security as provided in the Indenture.

            As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of Registered Securities is registrable on the
Security Register upon surrender of a Registered Security for registration of
transfer at the Corporate Trust Office of the Trustee or at such other office or
agency of the Company as may be designated by it for such purpose in the Borough
of Manhattan, The City of New York, or at such other offices or agencies as the
Company may designate, duly endorsed by, or accompanied by a written instrument
of transfer

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in form satisfactory to the Company and the Security Registrar duly executed by,
the Holder thereof or his attorney duly authorized in writing, and thereupon one
or more new Registered Securities, of authorized denominations and for the same
aggregate principal amount, will be issued to the designated transferee or
transferees by the Registrar. No service charge shall be made for any such
registration of transfer or exchange, but the Company may require payment of a
sum sufficient to recover any tax or other governmental charge payable in
connection therewith.

            Prior to due presentation of a Registered Security for registration
of transfer, the Company, the Trustee and any agent of the Company or the
Trustee may treat the Person in whose name such Registered Security is
registered as the owner thereof for all purposes, whether or not such Security
be overdue, and neither the Company, the Trustee nor any such agent shall be
affected by notice to the contrary.

            Interest on the Securities shall be computed on the basis of a
360-day year of twelve 30-day months. The Indenture and this Security shall be
governed by and construed in accordance with the laws of the State of New York,
United States of America, including, without limitation, Section 5-1401 of the
New York General Obligations Law.

            All terms used in this Security, which are defined in the Indenture,
shall have the meanings assigned to them in the Indenture.

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            ELECTION OF HOLDER TO REQUIRE CHANGE IN CONTROL PURCHASE

            1. Pursuant to Section 12.1 of the Indenture, the undersigned hereby
elects to have this Security purchased by the Company.

            2. The undersigned hereby directs the Trustee or the Company to pay
it or ___________________ an amount in cash equal to 100% of the principal
amount to be purchased (as set forth below), plus interest accrued to the Change
in Control Purchase Date and the Make-Whole Premium (if applicable) or, at the
Company's election, Common Stock or Successor Common Stock, valued as set forth
in the Indenture.

                                        Dated: _________________________________

                                        ________________________________________
                                        Signature
                                        Name of Holder: ________________________

                                        Signature Guaranteed

                                        ________________________________________
                                        Signature must be guaranteed by a
                                        participant in a recognized signature
                                        medallion program or other signature
                                        guarantor acceptable to the Trustee.

Principal amount to be purchased:

__________________________________________
(must be equal to U.S. $1,000 or any
greater integral multiple of U.S. $1,000):

Remaining principal amount following such purchase:

__________________________________________

NOTICE: The signature to the foregoing election must correspond to the name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.

<PAGE>

                                CONVERSION NOTICE

            The undersigned Holder of this Security hereby irrevocably exercises
the option to convert this Security, or any portion of the principal amount
hereof (which is an integral multiple of U.S.$1,000) below designated, into
shares of Common Stock in accordance with the terms of the Indenture referred to
in this Security and directs that such shares, together with a check in payment
for any fractional share and any Securities representing any unconverted
principal amount hereof, be delivered to and be registered in the name of the
undersigned unless a different name has been indicated below. If shares of
Common Stock or Securities are to be registered in the name of a Person other
than the undersigned, the undersigned will pay all transfer taxes payable with
respect thereto. Any amount required to be paid by the undersigned on account of
interest accompanies this Security.

Dated: _______________________________  ________________________________________

                                                       Signature

                                        Name of Holder:
                                        Title of Signatory:

If shares or Registered Securities are  If only a portion of the Securities is
to be registered in the name of a       to be converted, please indicate:
Person other than the Holder, please
print such Person's name and address:
                                        1.    Principal amount to be
                                              converted:

                                              U.S. $_________________________
______________________________________        (any integral multiple of U.S.
______________________________________        $1,000)
              Address
                                        2.    Principal amount and
______________________________________        denomination of Registered
Social Security or other Taxpayer             Securities representing
Identification Number, if any                 unconverted principal amount to
                                              be issued:
Signature Guarantee:

                                              Amount: U.S. $_________________
______________________________________
Signature must be guaranteed by a
participant in a recognized signature
guaranty medallion program or other
signature guarantor acceptable to the
Trustee.Exhibit 4.2

                                  VAXGEN, INC.,
                                    as Issuer

                         U.S. BANK NATIONAL ASSOCIATION
                                   as Trustee

                                    INDENTURE

                            Dated as of April 5, 2005

              5 1/2% CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2010

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>                                                                                       <C>
ARTICLE ONE DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION .................      1

      SECTION 1.1    Definitions ....................................................      1

      SECTION 1.2    Compliance Certificates and Opinions ...........................     12

      SECTION 1.3    Form of Documents Delivered to the Trustee .....................     12

      SECTION 1.4    Acts of Holders of Securities ..................................     13

      SECTION 1.5    Notices, Etc., to Trustee and Company ..........................     15

      SECTION 1.6    Notice to Holders of Securities; Waiver ........................     15

      SECTION 1.7    Effect of Headings and Table of Contents .......................     16

      SECTION 1.8    Successors and Assigns .........................................     16

      SECTION 1.9    Separability Clause ............................................     16

      SECTION 1.10   Benefits of Indenture ..........................................     16

      SECTION 1.11   Governing Law ..................................................     16

      SECTION 1.12   Legal Holidays .................................................     16

      SECTION 1.13   Conflict with Trust Indenture Act ..............................     17

      SECTION 1.14   Counterparts ...................................................     17

ARTICLE TWO THE SECURITIES ..........................................................     17

      SECTION 2.1    Form Generally .................................................     17

      SECTION 2.2    Title and Terms ................................................     18

      SECTION 2.3    Denominations ..................................................     19

      SECTION 2.4    Execution, Authentication, Delivery and Dating .................     19

      SECTION 2.5    Rule 144A Availability Date; Global Securities; Temporary
                     Securities .....................................................     19

      SECTION 2.6    Registration, Registration of Transfer and Exchange;
                     Restrictions on Transfer .......................................     22

      SECTION 2.7    Mutilated, Destroyed, Lost or Stolen Securities ................     24

      SECTION 2.8    Payment of Interest; Interest Rights Preserved .................     25

      SECTION 2.9    Persons Deemed Owners ..........................................     26
</TABLE>

                                      -i-
<PAGE>

<TABLE>
<S>                                                                                       <C>
      SECTION 2.10   Cancellation ...................................................     26

      SECTION 2.11   Computation of Interest ........................................     26

      SECTION 2.12   CUSIP Numbers ..................................................     26

ARTICLE THREE SATISFACTION AND DISCHARGE ............................................     27

      SECTION 3.1    Satisfaction and Discharge of Indenture ........................     27

      SECTION 3.2    Application of Trust Money .....................................     28

ARTICLE FOUR REMEDIES ...............................................................     29

      SECTION 4.1    Events of Default ..............................................     29

      SECTION 4.2    Acceleration of Maturity; Rescission and Annulment .............     30

      SECTION 4.3    Collection of Indebtedness and Suits for Enforcement by
                     Trustee ........................................................     31

      SECTION 4.4    Trustee May File Proofs of Claim ...............................     32

      SECTION 4.5    Trustee May Enforce Claims without Possession of Securities ....     33

      SECTION 4.6    Application of Money Collected .................................     33

      SECTION 4.7    Limitation on Suits ............................................     33

      SECTION 4.8    Unconditional Right of Holders to Receive Principal,
                     Premium and Interest and to Convert ............................     34

      SECTION 4.9    Restoration of Rights and Remedies .............................     34

      SECTION 4.10   Rights and Remedies Cumulative .................................     34

      SECTION 4.11   Delay or Omission Not Waiver ...................................     35

      SECTION 4.12   Control by Holders of Securities ...............................     35

      SECTION 4.13   Waiver of Past Defaults ........................................     35

      SECTION 4.14   Undertaking for Costs ..........................................     35

      SECTION 4.15   Waiver of Stay, Usury or Extension Laws ........................     36

ARTICLE FIVE THE TRUSTEE ............................................................     36

      SECTION 5.1    Certain Duties and Responsibilities ............................     36

      SECTION 5.2    Notice of Defaults .............................................     37

      SECTION 5.3    Certain Rights of Trustee ......................................     37

      SECTION 5.4    Not Responsible for Recitals or Issuance of Securities .........     39
</TABLE>

                                      -ii-
<PAGE>

<TABLE>
<S>                                                                                       <C>
      SECTION 5.5    May Hold Securities, Act as Trustee under Other Indentures .....     39

      SECTION 5.6    Money Held in Trust ............................................     39

      SECTION 5.7    Corporate Trustee Required; Eligibility ........................     40

      SECTION 5.8    Resignation and Removal; Appointment of Successor ..............     40

      SECTION 5.9    Acceptance of Appointment by Successor .........................     42

      SECTION 5.10   Merger, Conversion, Consolidation or Succession to Business ....     42

      SECTION 5.11   Authenticating Agents ..........................................     42

      SECTION 5.12   Disqualification; Conflicting Interests ........................     44

      SECTION 5.13   Preferential Collection of Claims Against Company ..............     44

ARTICLE SIX CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE ....................     44

      SECTION 6.1    Company May Consolidate, Etc., Only on Certain Terms ...........     44

      SECTION 6.2    Successor Substituted ..........................................     45

ARTICLE SEVEN SUPPLEMENTAL INDENTURES ...............................................     45

      SECTION 7.1    Supplemental Indentures without Consent of Holders of
                     Securities .....................................................     45

      SECTION 7.2    Supplemental Indentures with Consent of Holders of
                     Securities .....................................................     46

      SECTION 7.3    Execution of Supplemental Indentures ...........................     47

      SECTION 7.4    Effect of Supplemental Indentures ..............................     47

      SECTION 7.5    Reference in Securities to Supplemental Indentures .............     48

      SECTION 7.6    Notice of Supplemental Indentures ..............................     48

ARTICLE EIGHT COVENANTS .............................................................     48

      SECTION 8.1    Payment of Principal, Premium and Interest .....................     48

      SECTION 8.2    Maintenance of Offices or Agencies .............................     48

      SECTION 8.3    Money for Security Payments to Be Held in Trust ................     49

      SECTION 8.4    Existence ......................................................     50

      SECTION 8.5    Statement by Officers as to Default ............................     50

      SECTION 8.6    Delivery of Certain Information ................................     51
</TABLE>

                                      -iii-
<PAGE>

<TABLE>
<S>                                                                                       <C>
ARTICLE NINE PERSONAL REDEMPTION OF SECURITIES ......................................     51

      SECTION 9.1    Right of Redemption ............................................     51

      SECTION 9.2    Election to Redeem; Notice to Trustee ..........................     53

      SECTION 9.3    Selection by Trustee of Securities to Be Redeemed ..............     53

      SECTION 9.4    Notice of Redemption ...........................................     53

      SECTION 9.5    Deposit of Redemption Price ....................................     54

      SECTION 9.6    Securities Payable on Redemption Date ..........................     55

      SECTION 9.7    Securities Redeemed in Part ....................................     55

      SECTION 9.8    Conversion Arrangement on Call for Redemption ..................     56

ARTICLE TEN CONVERSION OF SECURITIES ................................................     57

      SECTION 10.1   Conversion Privilege and Conversion Rate .......................     57

      SECTION 10.2   Exercise of Conversion Privilege ...............................     57

      SECTION 10.3   Fractions of Shares ............................................     58

      SECTION 10.4   Adjustment of Conversion Rate ..................................     59

      SECTION 10.5   Notice of Adjustments of Conversion Rate .......................     63

      SECTION 10.6   Notice of Certain Corporate Action .............................     64

      SECTION 10.7   Company to Reserve Common Stock ................................     65

      SECTION 10.8   Taxes on Conversions ...........................................     65

      SECTION 10.9   Covenant as to Common Stock ....................................     65

      SECTION 10.10  Cancellation of Converted Securities ...........................     65

      SECTION 10.11  Provision in Case of Consolidation, Merger or Sale of
                     Assets .........................................................     65

      SECTION 10.12  Responsibility of Trustee for Conversion Provisions ............     66

      SECTION 10.13  Rights Distributions Pursuant to a Stockholders' Rights
                     Plan ...........................................................     67

      SECTION 10.14  No Adjustment ..................................................     67

      SECTION 10.15  Rights Issued in Respect of Common Stock .......................     67

ARTICLE ELEVEN SUBORDINATION OF SECURITIES ..........................................     68

      SECTION 11.1   Securities Subordinate to Senior Debt ..........................     68

      SECTION 11.2   No Payments in Certain Circumstances; Payment Over of
                     Proceeds Upon Dissolution, Etc .................................     68
</TABLE>

                                      -iv-
<PAGE>

<TABLE>
<S>                                                                                       <C>
      SECTION 11.3   Trustee to Effectuate Subordination ............................     70

      SECTION 11.4   No Waiver of Subordination Provisions ..........................     70

      SECTION 11.5   Notice to Trustee ..............................................     71

      SECTION 11.6   Reliance on Judicial Order or Certificate of Liquidating
                     Agent ..........................................................     71

      SECTION 11.7   Trustee Not Fiduciary for Holders of Senior Debt ...............     72

      SECTION 11.8   Reliance by Holders of Senior Debt on Subordination
                     Provisions .....................................................     72

      SECTION 11.9   Rights of Trustee as Holder of Senior Debt; Preservation of
                     Trustee's Rights ...............................................     72

      SECTION 11.10  Article Applicable to Paying Agents ............................     72

      SECTION 11.11  Certain Conversions and Repurchases Deemed Payment .............     73

ARTICLE TWELVE REPURCHASE UPON A CHANGE IN CONTROL ..................................     73

      SECTION 12.1   Purchase of Securities at Option of the Holder Upon Change
                     in Control .....................................................     73

      SECTION 12.2   Effect of Change in Control Purchase Notice ....................     79

      SECTION 12.3   Deposit of Change in Control Purchase Price ....................     80

      SECTION 12.4   Securities Purchased in Part ...................................     80

      SECTION 12.5   Covenant to Comply with Securities Laws Upon Purchase of
                     Securities .....................................................     81

      SECTION 12.6   Repayment to the Company .......................................     81

ARTICLE THIRTEEN [RESERVED] .........................................................     81

ARTICLE FOURTEEN HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY; NON-RECOURSE .....     81

      SECTION 14.1   Company to Furnish Trustee Names and Addresses of Holders ......     81

      SECTION 14.2   Preservation of Information ....................................     82

      SECTION 14.3   No Recourse Against Others .....................................     82

      SECTION 14.4   Reports by Trustee .............................................     82

      SECTION 14.5   Reports by Company .............................................     83
</TABLE>

                                      -v-
<PAGE>

      INDENTURE, dated as of April 5, 2005, between VaxGen, Inc., a corporation
duly organized and existing under the laws of the State of Delaware, having its
principal office at 1000 Marina Blvd., Suite 200, Brisbane, CA 94005 (herein
called the "Company"), and U.S. Bank National Association, a national banking
association, as Trustee hereunder (herein called the "Trustee").

                             RECITALS OF THE COMPANY

      The Company has duly authorized the creation of an issue of its 5 1/2%
Convertible Senior Subordinated Notes due 2010 (herein called the "Securities"),
of substantially the tenor and amount hereinafter set forth, and to provide
therefor the Company has duly authorized the execution and delivery of this
Indenture.

      All things necessary to make the Securities, when the Securities are
executed by the Company and authenticated and delivered hereunder, the valid and
legally binding obligations of the Company and to make this Indenture a valid
and legally binding agreement of the Company, in accordance with their and its
terms, have been done. Further, all things necessary to duly authorize the
issuance of shares of common stock of the Company issuable upon the conversion
of the Securities, and to duly reserve for issuance the number of shares of
Common Stock issuable upon such conversion, have been done.

      NOW, THEREFORE, THIS INDENTURE WITNESSETH:

      For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of the Securities, as follows:

                                  ARTICLE ONE

                        DEFINITIONS AND OTHER PROVISIONS
                             OF GENERAL APPLICATION

SECTION 1.1 Definitions.

      For all purposes of this Indenture, except as otherwise expressly provided
or unless the context otherwise requires:

      (a) the terms defined in this Article have the meanings assigned to them
in this Article and include the plural as well as the singular;

      (b) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles in
the United States; and

      (c) the words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Indenture as a whole and not to any particular
Article, Section or other subdivision.

                                      -1-
<PAGE>

      "Act," when used with respect to any Holder of a Security, has the meaning
specified in Section 1.4.

      "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"control," when used with respect to any specified Person, means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

      "Applicable Procedures" means, with respect to any transfer or transaction
involving a Global Security or beneficial interest therein, the rules and
procedures of the Depositary for such Security, to the extent applicable to such
transaction and as in effect from time to time.

      "Authenticating Agent" means any Person authorized pursuant to Section
5.12 to act on behalf of the Trustee to authenticate Securities.

      "Board of Directors" means either the board of directors of the Company or
any duly authorized committee of that board.

      "Board Resolution" means a resolution duly adopted by the Board of
Directors, a copy of which shall have been delivered to the Trustee and shall be
in full force and effect on the date of such delivery.

      "Business Day," when used with respect to any Place of Payment, Place of
Conversion or any other place, as the case may be, means each Monday, Tuesday,
Wednesday, Thursday and Friday that is not a day on which banking institutions
in such Place of Payment, Place of Conversion or other place, as the case may
be, are authorized or obligated by law or executive order to close; provided,
however, that a day on which banking institutions in New York, New York are
authorized or obligated by law or executive order to close shall not be a
Business Day for purposes of Section 9.6 or Section 10.5.

      "Capital Stock" of any Person means any and all shares, interests,
participations or other equivalents (however designated) of capital stock of
such Person and all warrants or options to acquire such capital stock.

      "Cash Equivalents" means (1) securities issued or directly and fully
guaranteed or insured by the United States government or any agency or
instrumentality thereof (provided that the full faith and credit of the United
States is pledged in support thereof) having maturities of not more than six
months from the date of acquisition, (2) certificates of deposit and eurodollar
time deposits with maturities of six months or less from the date of
acquisition, bankers' acceptances with maturities not exceeding six months and
overnight bank deposits, in each case with any domestic commercial bank having
capital and surplus in excess of $500 million and a Thompson Bank Watch Rating
of "B" or better, (3) repurchase obligations with a term of not more than seven
days for underlying securities of the types described in clause (1) above
entered into with any financial institution meeting the qualifications specified
in clause (2) above, (4) commercial paper having the highest rating obtainable
from Moody's Investors Service, Inc. or Standard & Poor's Ratings Services and
in each case maturing within six months after the date of

                                      -2-
<PAGE>

acquisition and (5) money market funds at least 95% of the assets of which
constitute Cash Equivalents of the kinds described in clauses (1)-(4) of this
definition.

      "Change in Control" means the occurrence at any time, after the original
issuance of the Securities, of any of the following events:

      (1) any Person or group (defined in accordance with Section 13(d)(3) of
the Exchange Act) acquires beneficial ownership (determined in accordance with
Rule 13d-3 under the Exchange Act), directly or indirectly, through a purchase,
merger or other acquisition transaction or series of transactions, of shares of
the Company's Capital Stock entitling that Person to exercise more than 50% of
the total voting power of all shares of the Company's Capital Stock entitled to
vote generally in elections of directors, provided that any acquisition or
ownership by the Company, its subsidiaries or its employee benefit plans will
not trigger this provision;

      (2) the Company consolidates with, or merges with or into, any other
Person or another Person merges into the Company or the Company conveys,
transfers, sells, leases or otherwise disposes of all or substantially all of
its assets to another Person, except if the transaction satisfies any of the
following:

            (a) the transaction is a merger (A) that does not result in any
      reclassification, conversion, exchange or cancellation of outstanding
      shares of the Company's Capital Stock and (B) pursuant to which holders of
      the Common Stock immediately prior to the transaction have, directly or
      indirectly, 50% or more of the total voting power of all shares of Capital
      Stock or other ownership interest in the continuing or surviving person
      entitled to vote generally in elections of directors of the continuing or
      surviving person immediately after the transaction;

            (b) the transaction is a merger effected only to change the
      Company's jurisdiction of incorporation and results in a reclassification,
      conversion or exchange of outstanding shares of the Common Stock only into
      shares of Common Stock of the Company or common stock of another
      corporation; or

            (c) at least 95% of the consideration for the Common Stock
      (excluding cash payments in lieu of fractional shares and cash payments
      made in respect of dissenters' appraisal rights) in the transaction or
      transactions constituting a change in control consists of common stock,
      depositary receipts or other certificates representing common equity
      interests traded on a U.S. national securities exchange or quoted on the
      Nasdaq National Market, or which will be so traded or quoted immediately
      following such transaction or transactions, and as a result of such
      transaction or transactions at least 95% of the value of the consideration
      for which the Securities become convertible consists of such common stock
      depositary receipts or other certificates representing common equity
      interests and any associated rights; or

      (3) the Company's stockholders pass a resolution approving a plan of
liquidation or dissolution and no additional approvals of stockholders are
required under applicable law to cause a liquidation or dissolution.

                                      -3-
<PAGE>

      "Change in Control Purchase Date" has the meaning specified in Section
12.1(a).

      "Change in Control Purchase Notice" has the meaning specified in Section
12.1(d).

      "Change in Control Purchase Price" has the meaning specified in Section
12.1(a).

      "Closing Sale Price" means the price of a share of Common Stock or
Successor Common Stock on the relevant date, determined (a) on the basis of the
closing per share sale price (or if no closing sale price is reported, the
average of the bid and ask prices or, if more than one in either case, the
average of the average bid and the average ask prices) on such date on the U.S.
principal securities exchange on which the Common Stock or Successor Common
Stock is listed; or (b) if the Common Stock or Successor Common Stock is not
listed on a U.S. national securities exchange, as reported by the National
Association of Securities Dealers Automated Quotation System; or (c) if not so
quoted, as reported by National Quotation Bureau, Incorporated or a similar
organization. In the absence of a quotation, the Closing Sale Price shall be
such price as the Company shall reasonably determine on the basis of such
quotations as most accurately reflecting the price that a fully informed buyer,
acting on his own accord, would pay to a fully informed seller, acting on his
own accord in an arms-length transaction, for a share of such Common Stock or
Successor Common Stock.

      "Code" has the meaning specified in Section 2.1.

      "Commission" means the United States Securities and Exchange Commission,
as from time to time constituted, created under the Exchange Act, or, if at any
time after the execution of this instrument such Commission is not existing and
performing the duties now assigned to it under the Trust Indenture Act, then the
body performing such duties at such time.

      "Common Stock" means the shares of the class designated as common stock of
the Company at the date of this Indenture or as such stock may be reconstituted
from time to time. Subject to the provisions of Section 10.11, shares issuable
on conversion or repurchase of Securities shall include only shares of Common
Stock or shares of any class or classes of common stock resulting from any
reclassification or reclassifications thereof; provided, however, that if at any
time there shall be more than one such resulting class, the shares so issuable
on conversion of Securities shall include shares of all such classes, and the
shares of each such class then so issuable shall be substantially in the
proportion that the total number of shares of such class resulting from all such
reclassifications bears to the total number of shares of all such classes
resulting from all such reclassifications.

      "Company" means the Person named as the "Company" in the first paragraph
of this instrument until a successor Person shall have become such pursuant to
the applicable provisions of this Indenture, and thereafter "Company" shall mean
such successor Person.

      "Company Notice" has the meaning specified in Section 12.1(c).

      "Company Request" or "Company Order" means a written request or order
signed in the name of the Company by an Officer of the Company, and delivered to
the Trustee.

      "Constituent Person" has the meaning specified in Section 10.11.

                                      -4-
<PAGE>

      "Conversion Agent" means any Person authorized by the Company to convert
Securities in accordance with Article Ten. The Company has initially appointed
the Trustee as its Conversion Agent.

      "Conversion Price" means the amount equal to U.S. $1,000 divided by the
Conversion Rate.

      "Conversion Rate" has the meaning specified in Section 10.1.

      "Conversion Shares" has the meaning specified in Section 10.4(c).

      "Corporate Trust Office" means the office of the Trustee at which at any
particular time its corporate trust business shall be principally administered
(which at the date of this Indenture is located at 60 Livingston Avenue, St.
Paul, MN 55107-2292, Attn: Corporate Trust Administration).

      "Corporation" means a corporation, company, association, joint-stock
company or business trust.

      "Current Market Price" has the meaning specified in Section 10.4(g).

      "Defaulted Interest" has the meaning specified in Section 2.8.

      "Depositary" means, with respect to any Registered Securities, a clearing
agency that is registered as such under the Exchange Act and is designated by
the Company to act as Depositary for such Registered Securities (or any
successor securities clearing agency so registered).

      "Designated Senior Debt" means the Company's obligations under any
particular Senior Debt in which the instrument creating or evidencing the same,
or the assumption or guarantee thereof, or related agreements or documents to
which the Company is a party, expressly provides that such indebtedness shall be
"Designated Senior Debt" for purposes of this Indenture (provided that such
instrument, agreement or other document may place limitations and conditions on
the right of such Senior Debt to exercise the rights of Designated Senior Debt).

      "Determination Date" has the meaning specified in Section 10.4(g).

      "Distribution Date" has the meaning specified in Section 10.4(c).

      "Dollar" or "U.S. $" means a dollar or other equivalent unit in such coin
or currency of the United States as at the time shall be legal tender for the
payment of public and private debts.

      "DTC" means The Depository Trust Company, a New York corporation.

      "Effective Date" has the meaning specified in Section 12.1.

      "Event of Default" has the meaning specified in Section 4.1.

                                      -5-
<PAGE>

      "Exchange Act" means the United States Securities Exchange Act of 1934 (or
any successor statute), as amended from time to time.

      "Expiration Time" has the meaning specified in Section 10.4(e).

      "Global Election Form" has the meaning specified in Section 2.5(a).

      "Global Security" means a Registered Security that is registered in the
Security Register in the name of a Depositary or a nominee thereof.

      "Holder" means the Person in whose name the Security is registered in the
Security Register.

      "Indenture" means this Indenture as originally executed or as it may from
time to time be supplemented or amended by one or more indentures supplemental
hereto entered into pursuant to the applicable provisions hereof, including, for
all purposes of this Indenture and any such supplemental indenture, the
provisions of the Trust Indenture Act that are deemed to be a part of and govern
this Indenture and any such supplemental indenture, respectively.

      "Interest Make-Whole Payment" means the amount equal to the present value
of the aggregate amount of the interest that would otherwise would have accrued
from the Redemption Date through the Stated Maturity of the Securities. The
present value will be calculated using the bond equivalent yield on U.S.
Treasury Notes or bills having a term (as compiled and published in the most
recent Federal Reserve Statistical Release H.15 (519) that has become publicly
available prior to the date of the Redemption Notice (or if such Statistical
Release is no longer published, any publicly available source of similar market
data)) nearest in length to that of the remaining period from the Redemption
Date through the Stated Maturity of the Securities; provided, however, that if
the period from such Redemption Date to the Stated Maturity of the Securities is
less than one year, then the weekly average yield on actually traded United
States Treasury securities adjusted to a constant maturity of one year will be
used in the calculation of the present value.

      "Interest Payment Date" means the Stated Maturity of an installment of
interest on the Securities.

      "Liquidated Damages" has the meaning specified in the Purchase Agreements.

      "Liquidated Damages Notice" has the meaning specified in Section 3.1.

      "Make-Whole Premium" has the meaning specified in Section 12.1(a).

      "Maturity," when used with respect to any Security, means the date on
which the principal of such Security becomes due and payable as therein or
herein provided, whether at the Stated Maturity or by declaration of
acceleration, call for redemption, exercise of the repurchase right set forth in
Article Twelve or otherwise.

      "Member" means any member of, or participant in, the Depositary.

                                      -6-
<PAGE>

      "Non-electing Share" has the meaning specified in Section 10.11.

      "Notice of Default" has the meaning specified in Section 4.1(d).

      "Officer" means the Chairman of the Board, a Vice Chairman of the Board,
the Chief Executive Officer, the Chief Operating Officer, the President, a
Senior Vice President, a Vice President, the Comptroller, the Controller, the
Chief Financial Officer, the Treasurer or an Assistant Treasurer of the Company.

      "Officers' Certificate" means a certificate signed by the Chairman of the
Board, a Vice Chairman of the Board, the Chief Executive Officer, the Chief
Operating Officer, the President, a Senior Vice President or a Vice President
and by the Comptroller, the Controller, the Chief Financial Officer, the
Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary of
the Company, and delivered to the Trustee.

      "Opinion of Counsel" means a written opinion of counsel, who may be
counsel for or employed by the Company.

      "Outstanding," when used with respect to Securities, means, as of the date
of determination, all Securities theretofore authenticated and delivered under
this Indenture, except:

      (1) Securities theretofore cancelled by the Trustee or delivered to the
Trustee for cancellation;

      (2) Securities for the payment or redemption of which money in the
necessary amount has been theretofore deposited with the Trustee or any Paying
Agent (if other than the Company) in trust or set aside and segregated in trust
by the Company (if the Company shall act as its own Paying Agent) for the
Holders of such Securities (provided that, if such Securities are to be
redeemed, notice of such redemption has been duly given pursuant to this
Indenture or provision therefor reasonably satisfactory to the Trustee has been
made); and

      (3) Securities that have been paid pursuant to Section 2.7 or in exchange
for or in lieu of which other Securities have been authenticated and delivered
pursuant to this Indenture, other than any such Securities in respect of which
there shall have been presented to the Trustee proof satisfactory to it that
such Securities are held by a bona fide purchaser in whose hands such Securities
are valid obligations of the Company;

provided, however, that in determining whether the Holders of the requisite
principal amount of Outstanding Securities are present at a meeting of Holders
of Securities for quorum purposes or have given any request, demand,
authorization, direction, notice, consent or waiver hereunder, Securities owned
by the Company or any other obligor upon the Securities or any Affiliate of the
Company or such other obligor shall be disregarded and deemed not to be
Outstanding, except that, in determining whether the Trustee shall be protected
in relying upon any such determination as to the presence of a quorum or upon
any such request, demand, authorization, direction, notice, consent or waiver,
only Securities that a Responsible Officer of the Trustee actually knows to be
so owned shall be so disregarded. Securities so owned that have been pledged in
good faith may be regarded as Outstanding if the pledgee establishes to the
reasonable satisfaction of the Trustee the pledgee's right so to act with
respect to such Securities and that the

                                      -7-
<PAGE>

pledgee is not the Company or any other obligor upon the Securities or any
Affiliate of the Company or such other obligor.

      "Paying Agent" means any Person authorized by the Company to pay the
principal of or interest on any Securities on behalf of the Company and, except
as otherwise specifically set forth herein, such term shall include the Company
if it shall act as its own Paying Agent. The Company has initially appointed the
Trustee as its Paying Agent.

      "Payment Blockage Notice" has the meaning specified in Section 11.2.

      "Person" means any individual, Corporation, limited liability company,
partnership, joint venture, trust, estate, unincorporated organization or
government or any agency or political subdivision thereof.

      "Place of Conversion" has the meaning specified in Section 2.2.

      "Place of Payment" has the meaning specified in Section 2.2.

      "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same debt as that evidenced by such
particular Security; and, for the purposes of this definition, any Security
authenticated and delivered under Section 2.7 in exchange for or in lieu of a
mutilated, destroyed, lost or stolen Security shall be deemed to evidence the
same debt as the mutilated, destroyed, lost or stolen Security.

      "Purchase Agreements" means the Purchase Agreements, dated as of March 30,
2005, among the Company and the several purchasers of the Securities, as such
agreements may be amended from time to time.

      "Purchased Shares" has the meaning specified in Section 10.4(e).

      "Purchasers" has the meaning specified in Section 9.8.

      "Record Date" means any Regular Record Date or Special Record Date.

      "Record Date Period" means the period from the close of business of any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date.

      "Redemption Date" has the meaning specified in Section 9.2.

      "Redemption Notice" has the meaning specified in Section 9.4.

      "Redemption Price" has the meaning specified in Section 9.1.

      "Registered Securities" has the meaning specified in Section 2.1.

      "Registrable Securities" has the meaning specified in the Purchase
Agreements.

      "Registration Statement" has the meaning specified in the Purchase
Agreements.

                                      -8-
<PAGE>

      "Regular Record Date" for interest payable in respect of any Registered
Security on any Interest Payment Date means the March 15 and the September 15
(whether or not a Business Day), as the case may be, next preceding such
Interest Payment Date.

      "Representative" means (1) the indenture trustee or other trustee, agent
or representative for any Designated Senior Debt or (2) with respect to
Designated Senior Debt that does not have any such trustee, agent or other
representative, (A) in the case of such Designated Senior Debt issued pursuant
to an agreement providing for voting arrangements as among the holders or owners
of such Designated Senior Debt, any holder or owner of such Designated Senior
Debt acting with the consent of the required Persons necessary to bind such
holders or owners of such Designated Senior Debt and (B) in the case of all
other such Designated Senior Debt, the holder or owner of such Designated Senior
Debt.

      "Responsible Officer," when used with respect to the Trustee, means any
officer within the Corporate Trust Office, including without limitation any vice
president, assistant vice president, assistant treasurer, corporate trust
officer or other employee of the Trustee customarily performing functions
similar to those performed by any of the above designated officers, and also
means, with respect to a particular corporate trust matter, any other officer to
whom such matter is referred because of his knowledge and familiarity with the
particular subject and who shall have direct responsibility for the
administration of this Indenture.

      "Restricted Global Security" has the meaning specified in Section 2.1.

      "Restricted Securities Legend" means, collectively, the legends
substantially in the forms of the legends required in the form of Security
attached hereto as Exhibit A to be placed upon each Security.

      "Rights" has the meaning specified in Section 10.4(c).

      "Rule 144A" means Rule 144A under the Securities Act (or any successor
provision), as it may be amended from time to time.

      "Rule 144A Availability Date" has the meaning specified in Section 2.5(a).

      "Rule 144A Information" has the meaning specified in Section 8.6.

      "Securities" has the meaning ascribed to it in the first paragraph under
the caption "Recitals of the Company."

      "Securities Act" means the United States Securities Act of 1933 (or any
successor statute), as amended from time to time.

      "Security Register" and "Security Registrar" have the respective meanings
specified in Section 2.6.

      "Senior Debt" means the principal of (and premium, if any) and interest
(including all interest accruing subsequent to the commencement of any
bankruptcy or similar proceeding, whether or not a claim for post-petition
interest is allowable as a claim in any such proceeding)

                                      -9-
<PAGE>

on, and rent payable on or in connection with, and all fees, costs, claims,
expenses and other amounts payable in connection with, the following, whether
absolute or contingent, secured or unsecured, due or to become due, outstanding
on the date of this Indenture or thereafter created, incurred or assumed: (1)
all the Company's indebtedness evidenced by a credit or loan agreement, note,
bond, debenture, or other similar instrument whether or not the recourse of the
lender is to all of the Company's assets or to only a portion, (2) all of the
Company's indebtedness, obligations and other liabilities, contingent or
otherwise, for borrowed money, including, without limitation, overdrafts,
foreign exchange contracts, currency exchange agreements, interest rate
protection agreements and any loans or advances from banks, whether or not
evidenced by notes or similar instruments, or bonds, debentures, notes or
similar instruments, whether or not the recourse of the lender is to all of the
Company's assets or only to a portion thereof, (3) bonds, debentures, notes or
similar instruments, whether or not the recourse of the lender is to all of the
Company's assets or to only a portion, (4) all of the Company's obligations as
lessee under leases required to be capitalized on the balance sheet of the
lessee under generally accepted accounting principles, (5) all of the Company's
obligations under leases for facilities, equipment or other assets entered into
for financing purposes, whether or not capitalized, (6) all of the Company's
obligations and other liabilities, contingent or otherwise, under any lease or
related document, including a purchase agreement, in connection with the lease
of real property or improvements, or any personal property included as part of
any such lease, which provides that the Company is contractually obligated to
purchase or cause a third party to purchase the leased property and thereby
guarantee a residual value of leased property to the lessor and all of the
Company's obligations under such lease or related document to purchase or cause
a third party to purchase the leased property, whether or not such lease
transaction is characterized as an operating lease or capitalized lease in
accordance with generally accepted accounting principles, (7) all of the
Company's obligations, contingent or otherwise, under interest rate and currency
swaps, caps, floors, collars, hedge agreements, forward contracts, or similar
agreements or arrangements, (8) all of the Company's obligations with respect to
letters of credit, bank guarantees, bankers' acceptances and similar facilities,
including related reimbursement obligations, (9) all of the Company's
obligations issued or assumed as the deferred purchase price of property or
services (but excluding trade accounts payable and accrued liabilities arising
in the ordinary course of business), (10) all of the Company's obligations of
the type referred to in clauses (1) through (9) above of another Person and all
dividends of another Person, the payment of which, in either case, the Company
has assumed or guaranteed or for which the Company is responsible or liable,
directly or indirectly, jointly or severally, as obligor, guarantor or otherwise
or which is secured by a lien on the Company's property and (11) renewals,
extensions, modifications, replacements, restatements and refundings of, or any
indebtedness or obligation issued in exchange for, any such indebtedness or
obligation described in clauses (1) through (10) of this definition; provided,
however, that Senior Debt shall not include (a) the Securities or (b) any
indebtedness or obligation if the terms of such indebtedness or obligation (or
the terms of the instrument under which such indebtedness or obligation is
issued) expressly provides that such indebtedness or obligation is not superior
in right of payment to the Securities; and provided, further, that Senior Debt
shall not include accounts payable or other accrued liabilities or obligations
incurred in the ordinary course of business in connection with the obtaining of
materials or services and any indebtedness or obligation that the Company may
owe to any direct or indirect Subsidiary.

                                      -10-
<PAGE>

      "Special Record Date" for the payment of any Defaulted Interest means a
date fixed by the Company pursuant to Section 2.8.

      "Stated Maturity," when used with respect to any Security or any
installment of interest thereon, means the date specified in such Security as
the fixed date on which the principal of such Security or such installment of
interest is due and payable.

      "Stock Price" has the meaning specified in Section 12.1.

      "Subsidiary" means a corporation more than 50% of the outstanding voting
stock of which is owned, directly or indirectly, by the Company or by one or
more other Subsidiaries, or by the Company and one or more other Subsidiaries.
For the purposes of this definition, "voting stock" means stock or other similar
interests in the corporation that ordinarily has or have voting power for the
election of directors or Persons performing similar functions, whether at all
times or only so long as no senior class of stock or other interests has or have
such voting power by reason of any contingency.

      "Successor Common Stock" has the meaning specified in Section 9.1(b).

      "Successor Security" of any particular Security means every Security
issued after, and evidencing all or a portion of the same debt as that evidenced
by, such particular Security; and, for the purposes of this definition, any
Security authenticated and delivered under Section 2.7 in exchange for or in
lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to
evidence the same debt as the mutilated, destroyed, lost or stolen Security.

      "Trading Days" means (1) if the Common Stock is listed or admitted for
trading on any national securities exchange, days on which such national
securities exchange is open for business; (2) if the Common Stock is quoted on
the Nasdaq National Market or any other system of automated dissemination of
quotations of securities prices, days on which trades may be effected through
such system; or (3) if the Common Stock is not listed or admitted for trading on
any national securities exchange or quoted on the Nasdaq National Market or any
other system of automated dissemination of quotation of securities prices, days
on which the Common Stock is traded regular way in the over-the-counter market
and for which a closing bid and a closing asked price for the Common Stock are
available.

      "Trigger Event" has the meaning specified in Section 10.14.

      "Trust Indenture Act" means the Trust Indenture Act of 1939 as in force at
the date as of which this Indenture was executed; provided, however, that in the
event the Trust Indenture Act of 1939 is amended after such date, "Trust
Indenture Act" means, to the extent required by any such amendment, the Trust
Indenture Act of 1939 as so amended.

      "Trustee" means the Person named as the "Trustee" in the first paragraph
of this Indenture until a successor Trustee shall have become such pursuant to
the applicable provisions of this Indenture, and thereafter "Trustee" shall mean
such successor Trustee.

      "Underlying Shares" has the meaning specified in Section 10.4(b).

                                      -11-
<PAGE>

      "United States" means the United States of America (including the several
States and the District of Columbia), its territories, its possessions and other
areas subject to its jurisdiction (its "possessions" including Puerto Rico, the
United States Virgin Islands, Guam, American Samoa, Wake Island and the Northern
Mariana Islands).

      "Vice President," when used with respect to the Company, means any vice
president, whether or not designated by a number or a word or words added before
or after the title "vice president."

SECTION 1.2 Compliance Certificates and Opinions.

      Upon any application or request by the Company to the Trustee to take any
action under any provision of this Indenture, the Company shall furnish to the
Trustee an Officers' Certificate stating that all conditions precedent, if any,
provided for in this Indenture relating to the proposed action have been
complied with and, if required by the Trust Indenture Act, an Opinion of Counsel
stating that in the opinion of such counsel all such conditions precedent, if
any, have been complied with, except that in the case of any such application or
request as to which the furnishing of such documents is specifically required by
any provision of this Indenture relating to such particular application or
request, no additional certificate or opinion need be furnished. Every
certificate or opinion with respect to compliance with a condition or covenant
provided for in this Indenture shall include:

      (a) a statement that each individual signing such certificate or opinion
has read such covenant or condition and the definitions herein relating thereto;

      (b) a brief statement as to the nature and scope of the examination or
investigation upon which the statements or opinions contained in such
certificate or opinion are based; (c) a statement that, in the opinion of such
individual, he has made such examination or investigation as is necessary to
enable him to express an informed opinion as to whether or not such covenant or
condition has been complied with; and

      (d) a statement as to whether, in the opinion of each such individual,
such condition or covenant has been complied with; provided, however, with
respect to matters of fact, an Opinion of Counsel may rely on an Officers'
Certificate or certificates of public officials.

SECTION 1.3 Form of Documents Delivered to the Trustee.

      In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

      Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representations by, counsel, unless such officer knows that the certificate or
opinion or representations with respect to the matters upon

                                      -12-
<PAGE>

which such certificate or opinion is based are erroneous. Any such certificate
or opinion of counsel may be based, insofar as it relates to factual matters,
upon a certificate or opinion of, or representations by, an officer or officers
of the Company or any other Person stating that the information with respect to
such factual matters is in the possession of the Company or such other Person,
unless such counsel knows that the certificate or opinion or representations
with respect to such matters are erroneous.

      Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.

SECTION 1.4 Acts of Holders of Securities.

      (a) Any request, demand, authorization, direction, notice, consent, waiver
or other action provided or permitted by this Indenture to be given or taken by
Holders of Securities may be embodied in and evidenced by one or more
instruments of substantially similar tenor signed by such Holders in person or
by an agent or proxy duly appointed in writing by such Holders. Such action
shall become effective when such instrument or instruments is delivered to the
Trustee and, where it is hereby expressly required, to the Company. The Trustee
shall promptly deliver to the Company copies of all such instruments delivered
to the Trustee. Such instrument or instruments (and the action embodied therein
and evidenced thereby) are herein sometimes referred to as the "Act" of the
Holders of Securities signing such instrument or instruments. Proof of execution
of any such instrument or of a writing appointing any such agent or proxy, or of
the holding by any Person of a Security, shall be sufficient for any purpose of
this Indenture and (subject to Section 5.1) conclusive in favor of the Trustee
and the Company if made in the manner provided in this Section 1.4.

      (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by a certificate of a notary public or other officer authorized by
law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. Where such
execution is by a signer acting in a capacity other than his individual
capacity, such certificate or affidavit shall also constitute sufficient proof
of his authority.

      (c) The principal amount and serial number of any Registered Security held
by any Person, and the date of his holding the same, shall be proved by the
Security Register.

      (d) The fact and date of execution of any such instrument or writing and
the authority of the Person executing the same may also be proved in any other
manner that the Trustee deems sufficient; and the Trustee may in any instance
require further proof with respect to any of the matters referred to in this
Section 1.4.

      (e) The Company may set any day as the record date for the purpose of
determining the Holders entitled to give or take any request, demand,
authorization, direction, notice, consent, waiver or other action, or to vote on
any action, authorized or permitted by this Indenture to be given or taken by
Holders. Promptly and in any case not later than ten days after setting a record
date, the Company shall notify the Trustee and the Holders of such record date.
If not set by the

                                      -13-
<PAGE>

Company prior to the first solicitation of a Holder made by any Person in
respect of any such action, or, in the case of any such vote, prior to such
vote, the record date for any such action or vote shall be the thirtieth day
(or, if later, the date of the most recent list of Holders required to be
provided pursuant to Section 14.1) prior to such first solicitation or vote, as
the case may be. With regard to any record date, the Holders on such date (or
their duly appointed agents or proxies), and only such Persons, shall be
entitled to give or take, or vote on, the relevant action, whether or not such
Holders remain Holders after such record date. Notwithstanding the foregoing,
the Company shall not set a record date for, and the provisions of this
paragraph shall not apply with respect to, any notice, declaration or direction
referred to in the next paragraph.

      Upon receipt by the Trustee from any Holder of (1) any notice of default
or breach referred to in Section 4.1(d), if such default or breach has occurred
and is continuing and the Trustee shall not have given such a notice to the
Company, (2) any declaration of acceleration referred to in Section 4.2, if an
Event of Default has occurred and is continuing and the Trustee shall not have
given such a declaration to the Company, or (3) any direction referred to in
Section 4.12, if the Trustee shall not have taken the action specified in such
direction, then, with respect to clauses (2) and (3), a record date shall
automatically and without any action by the Company or the Trustee be set for
determining the Holders entitled to join in such declaration or direction, which
record date shall be the close of business on the tenth day (or, if such day is
not a Business Day, the next succeeding Business Day) following the day on which
the Trustee receives such declaration or direction, and, with respect to clause
(1), the Trustee may set any day as a record date for the purpose of determining
the Holders entitled to join in such notice of default. Promptly after such
receipt by the Trustee of any such declaration or direction referred to in
clause (2) or (3), and promptly after setting any record date with respect to
clause (1), and as soon as practicable thereafter, the Trustee shall notify the
Company and the Holders of any such record date so fixed. The Holders on such
record date (or their duly appointed agents or proxies), and only such Persons,
shall be entitled to join in such notice, declaration or direction, whether or
not such Holders remain Holders after such record date; provided, however, that,
unless such notice, declaration or direction shall have become effective by
virtue of Holders of the requisite principal amount of Securities on such record
date (or their duly appointed agents or proxies) having joined therein on or
prior to the ninetieth day after such record date, such notice, declaration or
direction shall automatically and without any action by any Person be cancelled
and of no further effect. Nothing in this paragraph shall be construed to
prevent a Holder (or a duly appointed agent or proxy thereof) from giving,
before or after the expiration of such 90-day period, a notice, declaration or
direction contrary to or different from, or, after the expiration of such
period, identical to, the notice, declaration or direction to which such record
date relates, in which event a new record date in respect thereof shall be set
pursuant to this paragraph. In addition, nothing in this paragraph shall be
construed to render ineffective any notice, declaration or direction of the type
referred to in this paragraph given at any time to the Trustee and the Company
by Holders (or their duly appointed agents or proxies) of the requisite
principal amount of Securities on the date such notice, declaration or direction
is so given.

      (f) Except as provided in Sections 4.2 and 4.13, any request, demand,
authorization, direction, notice, consent, election, waiver or other Act of the
Holder of any Security shall bind every future Holder of the same Security and
the Holder of every Security issued upon the registration of transfer thereof or
in exchange therefor or in lieu thereof in respect of anything

                                      -14-
<PAGE>

done, omitted or suffered to be done by the Trustee or the Company in reliance
thereon, whether or not notation of such action is made upon such Security.

SECTION 1.5 Notices, Etc., to Trustee and Company.

      Any request, demand, authorization, direction, notice, consent, election,
waiver or other Act of Holders of Securities or other document provided or
permitted by this Indenture to be made upon, given or furnished to, or filed
with,

      (a) the Trustee by any Holder of Securities or by the Company shall be
sufficient for every purpose hereunder if made, given, furnished or filed in
writing to or with the Trustee and received at the Corporate Trust Office,
Attention: Corporate Trust Administration, and shall be deemed given when
received,

      (b) the Company by the Trustee or by any Holder of Securities shall be
sufficient for every purpose hereunder (unless otherwise herein expressly
provided) if in writing, mailed, first-class postage prepaid, or telecopied and
confirmed by mail, first-class postage prepaid, or delivered by hand or
overnight courier, addressed to the Company at 1000 Marina Blvd., Suite 200,
Brisbane, CA 94005, Attention: James M. Cunha, Chief Financial Officer (telecopy
no.: 650-624-1007), or at any other address previously furnished in writing to
the Trustee by the Company, and shall be deemed given when received.

      Any request, demand, authorization, direction, notice, consent, election
or waiver required or permitted under this Indenture shall be in the English
language, except that any published notice may be in an official language of the
country of publication.

SECTION 1.6 Notice to Holders of Securities; Waiver.

      Except as otherwise expressly provided herein, where this Indenture
provides for notice to Holders of Securities of any event, such notice shall be
sufficiently given to Holders if in writing and mailed, first-class postage
prepaid, to each Holder of a Security affected by such event, at the address of
such Holder as it appears in the Security Register, not earlier than the
earliest date and not later than the latest date prescribed for the giving of
such notice.

      Neither the failure to mail such notice, nor any defect in any notice so
mailed, to any particular Holder of a Registered Security shall affect the
sufficiency of such notice with respect to other Holders of Registered
Securities. In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification to Holders of Registered Securities as shall be made with
the approval of the Trustee, which approval shall not be unreasonably withheld
or delayed, shall constitute a sufficient notification to such Holders for every
purpose hereunder.

      Such notice shall be deemed to have been given when such notice is mailed.

      Where this Indenture provides for notice in any manner, such notice may be
waived in writing by the Person entitled to receive such notice, either before
or after the event, and such waiver shall be the equivalent of such notice.
Waivers of notice by Holders of Securities shall be

                                      -15-
<PAGE>

filed with the Trustee, but such filing shall not be a condition precedent to
the validity of any action taken in reliance upon such waiver.

SECTION 1.7 Effect of Headings and Table of Contents.

      The Article and Section headings herein and the Table of Contents are for
convenience only and shall not affect the construction hereof.

SECTION 1.8 Successors and Assigns.

      All covenants and agreements in this Indenture by the Company and by the
Trustee shall bind their respective successors and assigns, whether so expressed
or not.

SECTION 1.9 Separability Clause.

      In case any provision in this Indenture or the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 1.10 Benefits of Indenture.

      Except as provided in the next sentence, nothing in this Indenture or in
the Securities, express or implied, shall give to any Person, other than the
parties hereto and their successors and assigns hereunder and the Holders of
Securities, any benefit or legal or equitable right, remedy or claim under this
Indenture. The provisions of Article Eleven are intended to be for the benefit
of, and shall be enforceable directly by, the holders of Senior Debt.

SECTION 1.11 Governing Law.

      THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, THE UNITED STATES OF AMERICA,
INCLUDING, WITHOUT LIMITATION, THE NEW YORK GENERAL OBLIGATIONS LAW ss.5-1401.

SECTION 1.12 Legal Holidays.

      In any case where any Interest Payment Date, Redemption Date, Change in
Control Purchase Date or Stated Maturity of any Security or the last day on
which a Holder of a Security has a right to convert his Security shall not be a
Business Day at a Place of Payment or Place of Conversion, as the case may be,
then (notwithstanding any other provision of this Indenture or of the
Securities) payment of principal of, premium, if any, or interest (including
Liquidated Damages, if any) on, or the payment of the Change in Control Purchase
Price (whether the same is payable in cash or in shares of Common Stock,
Successor Common Stock or a combination thereof or otherwise) with respect to,
or delivery for conversion of, such Security need not be made at such Place of
Payment or Place of Conversion, as the case may be, on or by such day, but may
be made on or by the next succeeding Business Day at such Place of Payment or
Place of Conversion, as the case may be, with the same force and effect as if
made on the Interest

                                      -16-
<PAGE>

Payment Date, Redemption Date or Change in Control Purchase Date, or at the
Stated Maturity or by such last day for conversion; provided, however, that in
the case that payment is made on such succeeding Business Day, no interest shall
accrue on the amount so payable for the period from and after such Interest
Payment Date, Redemption Date, Change in Control Purchase Date, Stated Maturity
or last day for conversion, as the case may be.

SECTION 1.13 Conflict with Trust Indenture Act.

      If any provision hereof limits, qualifies or conflicts with a provision of
the Trust Indenture Act that is required under such act to be a part of and
govern this Indenture, the latter provision shall control. If any provision of
this Indenture modifies or excludes any provision of the Trust Indenture Act
that may be so modified or excluded, the latter provision shall be deemed to
apply to this Indenture as so modified or to be excluded, as the case may be.
Until such time as this Indenture shall be qualified under the Trust Indenture
Act, this Indenture, the Company and the Trustee shall be deemed for all
purposes hereof to be subject to and governed by the Trust Indenture Act to the
same extent as would be the case if this Indenture were so qualified on the date
hereof.

SECTION 1.14 Counterparts.

      This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

                                  ARTICLE TWO

                                 THE SECURITIES

SECTION 2.1 Form Generally.

      The Securities and the Trustee's Certificate of Authentication shall be in
substantially the form set forth in Exhibit A hereto, which Exhibit is a part of
this Indenture, with such appropriate insertions, omissions, substitutions and
other variations as are required or permitted by this Indenture, and may have
such letters, numbers or other marks of identification and such legends or
endorsements placed thereon as may be required to comply with the rules of any
securities exchange or the Internal Revenue Code of l986, as amended, and
regulations thereunder (the "Code"), or as may, consistently herewith, be
determined by the officers executing such Securities, as evidenced by their
execution thereof. All Securities shall be issued in registered form, as opposed
to bearer form, and shall sometimes be referred to as the "Registered
Securities."

      The Securities shall be printed, lithographed, typewritten or engraved or
produced by any combination of these methods on steel engraved borders, if so
required by any securities exchange upon which the Securities may be listed, or
may be produced in any other manner permitted by the rules of any such
securities exchange, or, if the Securities are not listed on a securities
exchange, in any other manner approved by the Company, all as determined by the
officers executing such Securities, as evidenced by their execution thereof.

                                      -17-
<PAGE>

      Upon their original issuance, Securities shall be issued in the form of
definitive Securities, without interest coupons, and shall be registered in the
name of the appropriate purchasers pursuant to the Purchase Agreements, and
shall each bear the Restricted Securities Legend.

      After the Rule 144 Availability Date, the Securities may be issued in the
form of one of more Global Securities without interest coupons which shall be
registered in the name of DTC, as Depositary, or its nominee and deposited with
the Trustee, as custodian for DTC, for credit by DTC to the respective accounts
of beneficial owners of the Securities represented thereby (or such other
accounts as they may direct). Such Global Security, together with its Successor
Securities that are Global Securities, are collectively herein called the
"Restricted Global Security."

SECTION 2.2 Title and Terms.

      The aggregate principal amount of Securities that may be authenticated and
delivered under this Indenture is limited to U.S. $31,500,000, except for
Securities authenticated and delivered in exchange for, or in lieu of, other
Securities pursuant to Section 2.5, 2.6, 2.7, 7.5, 9.7 or 10.2.

      The Securities shall be known and designated as the "5 1/2% Convertible
Senior Subordinate Notes due 2010" of the Company. Their Stated Maturity shall
be April 1, 2010 and they shall bear interest on their principal amount from
April 5, 2005, payable semiannually in arrears on April 1 and October 1 in each
year, commencing October 1, 2005, at the rate of 5 1/2% per annum until the
principal thereof is due and at the rate then in effect on any overdue principal
and, to the extent permitted by law, on any overdue interest; provided, however,
that payments shall only be made on Business Days as provided in Section 1.12.

      The principal of, premium, if any, and interest (including Liquidated
Damages, if any) on the Securities shall be payable as provided in the form of
Securities attached hereto as Exhibit A, and the Change in Control Price,
whether payable in cash or in shares of Common Stock, Successor Common Stock or
a combination thereof or otherwise, shall be payable at such places as are
identified in the Company Notice given pursuant to Section 12.1(c) (any city in
which any Paying Agent is located being herein called a "Place of Payment").

      Holders of Registrable Securities are entitled to the registration rights
set forth in the Purchase Agreements as provided by the form of Securities
attached hereto as Exhibit A. The Securities are entitled to the payment of
Liquidated Damages as provided in the Purchase Agreements.

      The Securities shall be provisionally redeemable, as provided in Article
Nine and in the form of Securities attached hereto as Exhibit A.

      The Securities shall be convertible as provided in Article Ten (any city
in which any Conversion Agent is located being herein called a "Place of
Conversion").

      The Securities shall be subordinated in right of payment to Senior Debt of
the Company as provided in Article Eleven.

                                      -18-
<PAGE>

      The Securities shall be subject to repurchase by the Company at the option
of the Holders as provided in Articles Twelve.

SECTION 2.3 Denominations.

      The Securities shall be issuable only in registered form, without coupons,
in denominations of U.S. $1,000 and integral multiples thereof.

SECTION 2.4 Execution, Authentication, Delivery and Dating.

      The Securities shall be executed on behalf of the Company by an Officer.
Any such signature may be manual or facsimile.

      Securities bearing the manual or facsimile signature of individuals who
were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Securities or did not
hold such offices at the date of such Securities.

      At any time and from time to time after the execution and delivery of this
Indenture, the Company may deliver Securities executed by the Company to the
Trustee or to its order for authentication, together with a Company Order for
the authentication and delivery of such Securities, and the Trustee in
accordance with such Company Order shall authenticate and make available for
delivery such Securities as provided in this Indenture and not otherwise.

      Each Security shall be dated the date of its authentication.

      No Security shall be entitled to any benefit under this Indenture or be
valid or obligatory for any purpose unless there appears on such Security a
certificate of authentication substantially in the form provided for herein
executed by the Trustee by manual signature of an authorized signatory, and such
certificate upon any Security shall be conclusive evidence, and the only
evidence, that such Security has been duly authenticated and delivered
hereunder.

SECTION 2.5 Rule 144A Availability Date; Global Securities; Temporary
            Securities.

      (a) Rule 144A Availability Date.

            (1) As promptly as practicable after the Securities may be
      transferred under applicable law to a "qualified institutional buyer" (as
      defined under Rule 144A) in accordance with Rule 144A (the "Rule 144A
      Availability Date"), the Trustee shall, at the request of the Company,
      mail to each Holder a form (the "Global Election Form"), which shall be in
      a form reasonably acceptable to the Trustee and the Company and which
      Global Election Form shall request that each Holder (or the custodian of
      such Holder's Security, if applicable) provide certain information with
      respect to such Holder's Security and return such completed Global
      Election Form and, if not already held by the Trustee, such Holder's
      definitive Security to the Trustee in order to exchange such Holder's
      definitive Security for a beneficial interest in the Global Security.

                                      -19-
<PAGE>

            (2) No crediting of a beneficial interest in the Global Security
      shall occur with respect to the definitive Securities that have not been
      delivered to the Trustee for cancellation (it being understood that any
      Securities held in custody by the Trustee as of the Rule 144A Availability
      Date shall be deemed so delivered to the Trustee for cancellation) or with
      respect to which a Global Election Form has not yet been delivered by or
      on behalf of the Holder. Upon issuance of the Global Securities and
      registration thereof in the name of the Depositary or a nominee thereof,
      the definitive Securities which have been previously delivered to or held
      by the Trustee, and with respect to which a Global Election Form has been
      delivered to or held by the Trustee, shall be cancelled and be of no
      further force or effect.

            (3) Each Global Election Form shall request (i) the name in which
      such Holder desires its beneficial interest in the Global Security to be
      registered, (ii) the relevant wire instructions for payments of principal,
      premium, interest and Liquidated Damages (if any), (iii) any required tax
      identification number, (iv) name and address information for delivery of
      notices and financial information of the Company pursuant to this
      Indenture, (v) participant account number to be credited with the
      beneficial interest in the Global Security in the aggregate principal
      amount of the definitive Security delivered by such Holder (or its
      custodian, as applicable) to the Trustee for cancellation and (vi) any
      other information reasonably requested by the Trustee for effecting the
      crediting of beneficial interests in the Global Security.

      (b) Global Securities.

            (1) Each Global Security authenticated under this Indenture shall be
      registered in the name of the Depositary designated by the Company for
      such Global Security or a nominee thereof and delivered to such Depositary
      or a nominee thereof or custodian therefor, and each such Global Security
      shall constitute a single Security for all purposes of this Indenture.

            (2) Notwithstanding any other provision in this Indenture, no Global
      Security may be exchanged in whole or in part for Securities registered,
      and no transfer of a Global Security in whole or in part may be
      registered, in the name of any Person other than the Depositary for such
      Global Security or a nominee thereof unless (A) such Depositary (i) has
      notified the Company that it is unwilling or unable to continue as
      Depositary for such Global Security or (ii) has ceased to be a clearing
      agency registered as such under the Exchange Act or announces an intention
      permanently to cease business or does in fact do so or (B) there shall
      have occurred and be continuing an Event of Default with respect to such
      Global Security.

            (3) If any Global Security is to be exchanged for other Securities
      or cancelled in whole, it shall be surrendered by or on behalf of the
      Depositary or its nominee to the Trustee, as Security Registrar, for
      exchange or cancellation, as provided in this Article Two. If any Global
      Security is to be exchanged for other Securities or cancelled in part, or
      if another Security is to be exchanged in whole or in part for a
      beneficial interest in any Global Security, in each case, as provided in
      Section 2.6, then either (A) such Global

                                      -20-
<PAGE>

      Security shall be so surrendered for exchange or cancellation, as provided
      in this Article Two, or (B) the principal amount thereof shall be reduced
      or increased by an amount equal to the portion thereof to be so exchanged
      or cancelled or equal to the principal amount of such other Security to be
      so exchanged for a beneficial interest therein, as the case may be, by
      means of an appropriate adjustment made on the records of the Trustee, as
      Security Registrar, whereupon the Trustee, in accordance with the
      Applicable Procedures, shall instruct the Depositary or its authorized
      representative to make a corresponding adjustment to its records. Upon any
      such surrender or adjustment of a Global Security, the Trustee shall,
      subject to Section 2.6(c) and as otherwise provided in this Article Two,
      authenticate and make available for delivery any Securities issuable in
      exchange for such Global Security (or any portion thereof) to or upon the
      order of, and registered in such names as may be directed by, the
      Depositary or its authorized representative. Upon the request of the
      Trustee in connection with the occurrence of any of the events specified
      in the preceding paragraph, the Company shall promptly make available to
      the Trustee a reasonable supply of Securities that are not in the form of
      Global Securities. The Trustee shall be entitled to rely upon any order,
      direction or request of the Depositary or its authorized representative,
      which is given or made pursuant to this Article Two.

            (4) Every Security authenticated and delivered upon registration of
      transfer of, or in exchange for or in lieu of, a Global Security or any
      portion thereof, whether pursuant to this Article Two or otherwise, shall
      be authenticated and delivered in the form of, and shall be, a registered
      Global Security, unless such Security is registered in the name of a
      Person other than the Depositary for such Global Security or a nominee
      thereof, in which case such Registered Security shall be authenticated and
      delivered in definitive, fully registered form, without interest coupons.

            (5) The Depositary or its nominee, as registered owner of a Global
      Security, shall be the Holder of such Global Security for all purposes
      under the Indenture and the Registered Securities, and owners of
      beneficial interests in a Global Security shall hold such interests
      pursuant to the Applicable Procedures. Accordingly, any such owner's
      beneficial interest in a Global Security shall be shown only on, and the
      transfer of such interest shall be effected only through, records
      maintained by the Depositary or its nominee or its agent members, and such
      owners of beneficial interests in a Global Security shall not be
      considered the owners or holders thereof.

      (c) Temporary Securities.

      Pending the preparation of definitive Securities, the Company may execute,
and upon Company Order the Trustee shall authenticate and make available for
delivery, temporary Securities which are printed, lithographed, typewritten,
mimeographed or otherwise produced, in any authorized denomination,
substantially of the tenor of the definitive Registered Securities in lieu of
which they are issued and with such appropriate insertions, omissions,
substitutions and other variations as the officers executing such Registered
Securities may determine, as evidenced by their execution of such Securities.

                                      -21-
<PAGE>

      If temporary Securities are issued, the Company shall cause definitive
Securities to be prepared without unreasonable delay. After the preparation of
definitive Securities, the temporary Securities shall be exchangeable for
definitive Securities upon surrender of the temporary Securities at any office
or agency of the Company designated pursuant to Section 8.2, without charge to
the Holder. Upon surrender for cancellation of any one or more temporary
Securities, the Company shall execute and the Trustee shall authenticate and
make available for delivery in exchange therefor a like principal amount of
definitive Securities of authorized denominations. Until so exchanged, the
temporary Securities shall in all respects be entitled to the same benefits
under this Indenture as definitive Securities.

SECTION 2.6 Registration, Registration of Transfer and Exchange; Restrictions on
            Transfer.

      (a) The Company shall cause to be kept at the Corporate Trust Office a
register (the register maintained in such office and in any other office or
agency of the Company designated pursuant to Section 8.2 being herein sometimes
collectively referred to as the "Security Register") in which, subject to such
reasonable regulations as it may prescribe, the Company shall provide for the
registration of Registered Securities and of transfers of Registered Securities.
The Trustee is hereby appointed "Security Registrar" for the purpose of
registering Registered Securities and transfers and exchanges of Registered
Securities as herein provided.

      Upon surrender for registration of transfer of any Security at an office
or agency of the Company designated pursuant to Section 8.2 for such purpose,
the Company shall execute, and the Trustee shall authenticate and deliver, in
the name of the designated transferee or transferees, one or more new Securities
of any authorized denominations and of a like aggregate principal amount and
bearing such restrictive legends as may be required by this Indenture.

      At the option of the Holder, and subject to the other provisions of this
Section 2.6, Securities may be exchanged for other Securities of any authorized
denomination and of a like aggregate principal amount, upon surrender of the
Securities to be exchanged at any such office or agency. Whenever any Securities
are so surrendered for exchange, and subject to the other provisions of this
Section 2.6, the Company shall execute, and the Trustee shall authenticate and
make available for delivery, the Securities the Holder making the exchange is
entitled to receive. Every Security presented or surrendered for registration of
transfer or for exchange shall (if so required by the Company or the Security
Registrar) be duly endorsed, or be accompanied by a written instrument of
transfer in form satisfactory to the Company and the Security Registrar, duly
executed by the Holder thereof or his attorney duly authorized in writing.

      All Securities issued upon any registration of transfer or exchange of
Securities shall be the valid obligations of the Company, evidencing the same
debt, subject to the other provisions of this Section 2.6, and entitled to the
same benefits under this Indenture, as the Securities surrendered upon such
registration of transfer or exchange.

      No service charge shall be made for any registration of transfer or
exchange of Securities except as provided in Section 2.7, but the Company may
require payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed in connection with any registration of transfer or
exchange of Securities, other than exchanges pursuant to Section 2.5,

                                      -22-
<PAGE>

7.5, 9.7 or 10.2 (other than where the shares of Common Stock are to be issued
or delivered in a name other than that of the Holder of the Security) not
involving any transfer and other than any stamp and other duties, if any, that
may be imposed in connection with any such transfer or exchange by the United
States or any political subdivision thereof or therein, which shall be paid by
the Company.

      In the event of a redemption of the Securities, the Company shall not be
required (1) to register the transfer of or exchange Securities for a period of
15 days immediately preceding the date notice is given identifying the serial
numbers of the Securities called for such redemption or (2) to register the
transfer of or exchange any Security, or portion thereof, called for redemption.

      (b) All Securities shall bear the applicable Restricted Securities Legend
subject to the following:

            (1) subject to the following clauses of this Section 2.6(b), a
      Security or any portion thereof that is exchanged, upon transfer or
      otherwise, for a Global Security or any portion thereof shall bear the
      Restricted Securities Legend borne by such Global Security while
      represented thereby;

            (2) subject to the following clauses of this Section 2.6(b), a new
      Security that is not a Global Security and is issued in exchange for
      another Security (including a Global Security) or any portion thereof,
      upon transfer or otherwise, shall bear the Restricted Securities Legend
      borne by such other Security;

            (3) any Securities that are sold or otherwise disposed of pursuant
      to an effective registration statement under the Securities Act (including
      the Registration Statement), together with their Successor Securities,
      shall not bear a Restricted Securities Legend; the Company shall inform
      the Trustee in writing of the effective date of any such registration
      statement registering the Securities under the Securities Act and shall
      notify the Trustee at any time when prospectuses may not be delivered with
      respect to Securities to be sold pursuant to such registration statement.
      The Trustee shall not be liable for any action taken or omitted to be
      taken by it in good faith in accordance with the aforementioned
      registration statement;

            (4) at any time after the Securities may be freely transferred
      without registration under the Securities Act or without being subject to
      transfer restrictions pursuant to the Securities Act, a new Security that
      does not bear a Restricted Securities Legend may be issued in exchange for
      or in lieu of a Security (other than a Global Security) or any portion
      thereof that bears such a legend if the Trustee has received a certificate
      regarding the unrestricted nature of the Securities, satisfactory to the
      Trustee and duly executed by the Holder of such legended Security or his
      attorney duly authorized in writing, and after such date and receipt of
      such certificate, the Trustee shall authenticate and make available for
      delivery such a new Security in exchange for or in lieu of such other
      Security as provided in this Article Two;

            (5) a new Security that does not bear a Restricted Securities Legend
      may be issued in exchange for or in lieu of a Security (other than a
      Global Security) or any

                                      -23-
<PAGE>

      portion thereof that bears such a legend if, in the Company's judgment,
      placing such a legend upon such new Security is not necessary to ensure
      compliance with the registration requirements of the Securities Act, and
      the Trustee, at the direction of the Company, shall authenticate and make
      available for delivery such a new Security as provided in this Article
      Two; and

            (6) notwithstanding the foregoing provisions of this Section 2.6(b),
      a Successor Security of a Security that does not bear a particular form of
      Restricted Securities Legend shall not bear such form of legend unless the
      Company has reasonable cause to believe that such Successor Security is a
      "restricted security" within the meaning of Rule 144 under the Securities
      Act, in which case the Trustee, at the direction of the Company, shall
      authenticate and make available for delivery a new Security bearing a
      Restricted Securities Legend in exchange for such Successor Security as
      provided in this Article Two.

      (c) Neither the Trustee, the Paying Agent nor any of their agents shall
(1) have any duty to monitor compliance with or with respect to any federal or
state or other securities or tax laws or (2) have any duty to obtain
documentation on any transfers or exchanges other than as specifically required
hereunder.

SECTION 2.7 Mutilated, Destroyed, Lost or Stolen Securities.

      If any mutilated Security is surrendered to the Trustee, the Company shall
execute and the Trustee shall authenticate and make available for delivery in
exchange therefor a new Security of like tenor and principal amount and bearing
a number not contemporaneously outstanding.

      If there be delivered to the Company and to the Trustee:

      (a) evidence to their satisfaction of the destruction, loss or theft of
any Security, and

      (b) such security or indemnity as may be satisfactory to the Company and
the Trustee to save each of them and any agent of either of them harmless,

then, in the absence of actual notice to the Company or the Trustee that such
Security has been acquired by a bona fide purchaser, the Company shall execute
and the Trustee shall authenticate and make available for delivery, in lieu of
any such destroyed, lost or stolen Security, a new Security of like tenor and
principal amount and bearing a number not contemporaneously outstanding.

      In case any such mutilated, destroyed, lost or stolen Security has become
or is about to become due and payable, the Company in its discretion, but
subject to any conversion rights, may, instead of issuing a new Security, pay
such Security, upon satisfaction of the conditions set forth in the preceding
paragraph.

      Upon the issuance of any new Security under this Section 2.7, the Company
may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be

                                      -24-
<PAGE>

imposed in relation thereto (other than any stamp and other duties, if any, that
may be imposed in connection therewith by the United States or any political
subdivision thereof or therein, which shall be paid by the Company) and any
other expenses (including the fees and expenses of the Trustee) connected
therewith.

      Every new Security issued pursuant to this Section 2.7 in lieu of any
mutilated, destroyed, lost or stolen Security shall constitute an original
additional contractual obligation of the Company, whether or not the mutilated,
destroyed, lost or stolen Security shall be at any time enforceable by anyone,
and such new Security shall be entitled to all the benefits of this Indenture
equally and proportionately with any and all other Securities duly issued
hereunder.

      The provisions of this Section 2.7 are exclusive and shall preclude (to
the extent lawful) all other rights and remedies of any Holder with respect to
the replacement or payment of mutilated, destroyed, lost or stolen Securities.

SECTION 2.8 Payment of Interest; Interest Rights Preserved.

      Interest (including Liquidated Damages, if any) on any Security that is
payable, and is punctually paid or duly provided for, on any Interest Payment
Date shall be paid to the Person in whose name that Security (or one or more
Predecessor Securities) is registered at the close of business on the Regular
Record Date for such interest.

      Any interest (including Liquidated Damages, if any) on any Security that
is payable, but is not punctually paid or duly provided for, on any Interest
Payment Date ("Defaulted Interest") shall forthwith cease to be payable to the
Holder on the relevant Regular Record Date by virtue of having been such Holder,
and such Defaulted Interest may be paid by the Company, at its election in each
case, as provided in clause (a) or (b) below:

      (a) The Company may elect to make payment of any Defaulted Interest to the
Persons in whose names the Securities (or their respective Predecessor
Securities) are registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest, which shall be fixed in the following
manner. The Company shall notify the Trustee in writing of the amount of
Defaulted Interest proposed to be paid on each Security, the date of the
proposed payment and the Special Record Date, and at the same time the Company
shall deposit with the Trustee an amount of money equal to the aggregate amount
proposed to be paid in respect of such Defaulted Interest or shall make
arrangements reasonably satisfactory to the Trustee for such deposit prior to
the date of the proposed payment, such money when deposited to be held in trust
for the benefit of the Persons entitled to such Defaulted Interest as provided
in this clause. The Special Record Date for the payment of such Defaulted
Interest shall be not more than 15 days and not less than 10 days prior to the
date of the proposed payment and not less than 15 days after the receipt by the
Trustee of the notice of the proposed payment. The Trustee, in the name and at
the expense of the Company, shall cause notice of the proposed payment of such
Defaulted Interest and the Special Record Date therefor to be mailed,
first-class postage prepaid, to each Holder at such Holder's address as it
appears in the Security Register, not less than 10 days prior to such Special
Record Date. Notice of the proposed payment of such Defaulted Interest and the
Special Record Date therefor having been so mailed, such Defaulted Interest
shall be paid to the Persons in whose names the Securities (or their respective

                                      -25-
<PAGE>

Predecessor Securities) are registered at the close of business on such Special
Record Date and shall no longer be payable pursuant to the following clause (b).

      (b) The Company may make payment of any Defaulted Interest in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities may be listed, and upon such notice as may be required
by such exchange, if, after notice given by the Company to the Trustee of the
proposed payment pursuant to this clause, such manner of payment shall be deemed
practicable by the Trustee.

      Subject to the foregoing provisions of this Section 2.8 and Section 2.6,
each Security delivered under this Indenture upon registration of transfer of or
in exchange for or in lieu of any other Security shall carry the rights to
interest accrued and unpaid, and to accrue, that were carried by such other
Security.

      Interest on any Security that is converted in accordance with Section 10.2
during a Record Date Period shall be payable in accordance with the provisions
of Section 10.2.

SECTION 2.9 Persons Deemed Owners.

      Prior to due presentment of a Security for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
Person in whose name such Security is registered as the owner of such Security
for the purpose of receiving payment of principal of, premium, if any, and
(subject to Section 2.8) interest (including Liquidated Damages, if any) on such
Security and for all other purposes whatsoever, whether or not such Security be
overdue, and neither the Company, the Trustee nor any agent of the Company or
the Trustee shall be affected by notice to the contrary.

SECTION 2.10 Cancellation.

      All Securities surrendered for payment, redemption, repurchase,
registration of transfer or exchange or conversion shall, if surrendered to any
Person other than the Trustee, be delivered to the Trustee. All Securities so
delivered to the Trustee shall be cancelled promptly by the Trustee. No
Securities shall be authenticated in lieu of or in exchange for any Securities
cancelled as provided in this Section 2.10. The Trustee shall dispose of all
cancelled Securities in accordance with applicable law and its customary
practices in effect from time to time.

SECTION 2.11 Computation of Interest.

      Interest on the Securities shall be computed on the basis of a 360-day
year of twelve 30-day months.

SECTION 2.12 CUSIP Numbers.

      The Company in issuing Securities may use "CUSIP" numbers (if then
generally in use) in addition to serial numbers; the Trustee shall use such
CUSIP numbers in addition to serial numbers in notices of redemption and
repurchase as a convenience to Holders; provided, however, that any such notice
may state that no representation is made as to the correctness of such CUSIP
numbers either as printed on the Securities or as contained in any notice of a

                                      -26-
<PAGE>

redemption or repurchase and that reliance may be placed only on the serial or
other identification numbers printed on the Securities, and any such redemption
or repurchase shall not be affected by any defect in or omission of such CUSIP
numbers. The Company shall promptly notify the Trustee in writing of any change
in any such CUSIP number.

                                 ARTICLE THREE

                           SATISFACTION AND DISCHARGE

SECTION 3.1 Satisfaction and Discharge of Indenture.

      This Indenture shall upon Company Request cease to be of further effect
(except as to any surviving rights of conversion, or registration of transfer or
exchange, or replacement of Securities herein expressly provided for and any
right to receive Liquidated Damages as provided in the form of Securities
attached hereto as Exhibit A and the Company's obligations to the Trustee
pursuant to Section 5.7), and the Trustee, at the expense of the Company, shall
execute proper instruments in form and substance reasonably satisfactory to the
Trustee acknowledging satisfaction and discharge of this Indenture, when

      (a) either:

            (1) all Securities theretofore authenticated and delivered (other
      than (A) Securities that have been destroyed, lost or stolen and that have
      been replaced or paid as provided in Section 2.7 and (B) Securities for
      whose payment money has theretofore been deposited in trust or segregated
      and held in trust by the Company and thereafter repaid to the Company or
      discharged from such trust, as provided in Section 8.3) have been
      delivered to the Trustee for cancellation, other than in connection with
      the surrender of definitive Securities in exchange for beneficial
      interests in the Global Security pursuant to Section 2.5; or

            (2) all such Securities not theretofore delivered to the Trustee or
      its agent for cancellation (other than Securities referred to in clauses
      (A) and (B) of clause (a)(1) above)

            (i) have become due and payable, or

            (ii) will have become due and payable at their Stated Maturity
      within one year, or

            (iii) are to be called for redemption within one year under
      arrangements reasonably satisfactory to the Trustee for the giving of
      notice of redemption by the Trustee in the name, and at the expense, of
      the Company,

      and the Company, in the case of clause (i), (ii) or (iii) above, has
      deposited or caused to be deposited with the Trustee as trust funds
      (immediately available to the Holders in the case of clause (i) above) an
      amount sufficient to pay and discharge the entire principal,

                                      -27-
<PAGE>

      premium, if any, and interest (including Liquidated Damages, if any) on
      such Securities not theretofore delivered to the Trustee for cancellation,
      to the date of such deposit (in the case of Securities that have become
      due and payable) or to the Stated Maturity or Redemption Date, as the case
      may be;

      (b) the Company has paid or caused to be paid all other sums payable
hereunder by the Company; and

      (c) the Company has delivered to the Trustee an Officers' Certificate
stating that all conditions precedent herein provided for relating to the
satisfaction and discharge of this Indenture have been complied with.

      Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 5.7, the obligations of
the Company to any Authenticating Agent under Section 5.12, the obligation of
the Company to pay Liquidated Damages, the obligations of the Trustee under
Section 3.2 and the last paragraph of Section 8.3, if money shall have been
deposited with the Trustee pursuant to clause (a)(2) of this Section 3.1, and
the obligations of the Company and the Trustee under Section 2.6 and Article Ten
shall survive such satisfaction and discharge. Funds held in trust pursuant to
this Section 3.1 are not subject to the provisions of Article Eleven.

      In the event that the Company is required to pay Liquidated Damages to the
Holders pursuant to the Purchase Agreement, the Company will provide written
notice ("Liquidated Damages Notice") to the Trustee of its obligation to pay
Liquidated Damages no later than 15 days prior to the proposed payment date for
the Liquidated Damages, and the Liquidated Damages Notice shall set forth the
amount of Liquidated Damages to be paid by the Company on such payment date. The
Trustee shall not at any time be under any duty or responsibility to any Holder
to determine the Liquidated Damages or with respect to the nature, extent or
calculation of the amount of Liquidated Damages when made, or with respect to
the method employed in such calculation of the Liquidated Damages. Unless the
Trustee receives an Liquidated Damages Notice within the time period specified
above, the Trustee is entitled to assume that no Liquidated Damages is due and
payable.

SECTION 3.2 Application of Trust Money.

      Subject to the provisions of the last paragraph of Section 8.3, all money
deposited with the Trustee pursuant to Section 3.1 shall be held in trust and
applied by it, in accordance with the provisions of the Securities and this
Indenture, to the payment, either directly or through any Paying Agent
(including the Company acting as its own Paying Agent), to the Persons entitled
thereto, of the principal, premium, if any, and interest (including Liquidated
Damages, if any) for whose payment such money has been deposited with the
Trustee.

      All moneys deposited with the Trustee pursuant to Section 3.1 (and held by
it or any Paying Agent) for the payment of Securities subsequently converted
shall be returned to the Company.

                                      -28-
<PAGE>

                                  ARTICLE FOUR

                                    REMEDIES

SECTION 4.1 Events of Default.

      "Event of Default," wherever used herein, means any one of the following
events (whatever the reason for such Event of Default and whether it shall be
occasioned by the provisions of Article Eleven or be voluntary or involuntary or
be effected by operation of law or pursuant to any judgment, decree or order of
any court or any order, rule or regulation of any administrative or governmental
body):

      (a) default in the payment of the principal of or premium, if any, on any
Security at its Maturity, whether or not the such payment is prohibited by the
subordination provisions of this Indenture; or

      (b) default in the payment of any interest (including Liquidated Damages,
if any) upon any Security when it becomes due and payable, and continuance of
such default for a period of 30 days, whether or not such payment is prohibited
by the subordination provisions of this Indenture; or

      (c) failure by the Company to give the Company Notice in accordance with
Section 12.1(c), whether or not such notice is prohibited by the subordination
provisions of this Indenture; or

      (d) default in the performance or observance, or breach, of any other
term, covenant or agreement of the Company in this Indenture or the Securities
(other than a covenant a default in the performance or breach of which is
specifically dealt with elsewhere in this Section 4.1), and continuance of such
default or breach for a period of 60 days after there has been given, by
registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least 25% in aggregate principal amount of
the Outstanding Securities, a written notice specifying such default or breach
and requiring it to be remedied and stating that such notice is a "Notice of
Default" hereunder; or

      (e) (i) default in the payment by the end of the applicable grace period
or after maturity of the principal of any indebtedness under any bond,
debenture, note or other evidence of indebtedness for money borrowed by the
Company or any Subsidiary in excess of U.S. $10,000,000, whether such
indebtedness now exists or shall hereafter be created, if the indebtedness is
not discharged, or (ii) if such indebtedness has been accelerated, such
acceleration is not rescinded or annulled, in the case of either (i) or (ii)
above, within a period of 30 days after there shall have been given, by
registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least 25% in principal amount of the
Outstanding Securities a written notice specifying such default and requiring
the Company to cause such indebtedness to be discharged or such acceleration to
be rescinded or annulled and stating that such notice is a "Notice of Default"
hereunder; or

                                      -29-
<PAGE>

      (f) the entry by a court having jurisdiction in the premises of (1) a
decree or order for relief in respect of the Company or any Subsidiary in an
involuntary case or proceeding under any applicable federal or state bankruptcy,
insolvency, reorganization or other similar law or (2) a decree or order
adjudging the Company or any Subsidiary as bankrupt or insolvent, or approving
as properly filed a petition seeking reorganization, arrangement, adjustment or
composition of or in respect of the Company or any Subsidiary under any
applicable federal or state law, or appointing a custodian, receiver,
liquidator, assignee, trustee, sequestrator or other similar official of the
Company or any Subsidiary or of any substantial part of its property, or
ordering the winding up or liquidation of its affairs, and the continuance of
any such decree or order for relief or any such other decree or order unstayed
and in effect for a period of 60 consecutive days;

      (g) the commencement by the Company or any Subsidiary of a voluntary case
or proceeding under any applicable federal or state bankruptcy, insolvency,
reorganization or other similar law or of any other case or proceeding to be
adjudicated a bankrupt or insolvent, or the consent by it to the entry of a
decree or order for relief in respect of the Company or any Subsidiary in an
involuntary case or proceeding under any applicable federal or state bankruptcy,
insolvency, reorganization or other similar law or to the commencement of any
bankruptcy or insolvency case or proceeding against it, or the filing by it of a
petition or answer or consent seeking reorganization or similar relief under any
applicable federal or state law, or the consent by it to the filing of such
petition or to the appointment of or taking possession by a custodian, receiver,
liquidator, assignee, trustee, sequestrator or other similar official of the
Company or any Subsidiary or of any substantial part of its property, or the
making by it of an assignment for the benefit of creditors, or the admission by
it in writing of its inability to pay its debts generally as they become due, or
the taking of corporate action by the Company or any Subsidiary in furtherance
of any such action; or

      (h) the failure by the Company to deliver shares of Common Stock, together
with cash in lieu of fractional shares, when those shares of Common Stock and
cash in lieu of fractional shares are required to be delivered upon conversion
of a Security, and such failure continues for 10 days after delivery by a Holder
of upon delivery of the Security in accordance with Article Ten.

SECTION 4.2 Acceleration of Maturity; Rescission and Annulment.

      If an Event of Default (other than an Event of Default specified in
Section 4.1(f) or 4.1(g) with respect to the Company) occurs and is continuing,
then in every such case the Trustee or the Holders of not less than 25% in
principal amount of the Outstanding Securities may declare the principal of all
the Securities to be due and payable immediately, by a notice in writing to the
Company (and to the Trustee if given by the Holders), and upon any such
declaration, such principal and all accrued interest (including Liquidated
Damages, if any) thereon shall become immediately due and payable. If an Event
of Default specified in Section 4.1(f) or 4.1(g) with respect to the Company
occurs, the principal of, and accrued interest (including Liquidated Damages, if
any) on, all the Securities shall ipso facto become immediately due and payable
without any declaration or other Act of the Holder or any act on the part of the
Trustee.

                                      -30-
<PAGE>

      At any time after such declaration of acceleration has been made and
before a judgment or decree for payment of the money due has been obtained by
the Trustee as hereinafter in this Article Four provided, the Holders of a
majority in principal amount of the Outstanding Securities, by written notice to
the Company and the Trustee, may rescind and annul such declaration and its
consequences if:

      (a) the Company has paid or deposited with the Trustee a sum sufficient to
pay

            (1) all overdue interest (including Liquidated Damages, if any) on
      all Securities,

            (2) the principal of and premium, if any, on any Securities that
      have become due otherwise than by such declaration of acceleration and any
      interest thereon (including Liquidated Damages, if any) at the rate borne
      by the Securities,

            (3) to the extent permitted by applicable law, interest upon overdue
      interest (including Liquidated Damages, if any) at the rate then in
      effect, and

            (4) all sums paid or advanced by the Trustee hereunder and the
      reasonable compensation, expenses, disbursements and advances of the
      Trustee, its agents and its counsel; and

      (b) all Events of Default, other than the non-payment of the principal of,
and any premium and interest on, Securities that have become due solely by such
declaration of acceleration, have been cured or waived as provided in Section
4.13.

      No rescission or annulment referred to above shall affect any subsequent
default or impair any right consequent thereon.

SECTION 4.3 Collection of Indebtedness and Suits for Enforcement by Trustee.

      The Company covenants that if:

      (a) default is made in the payment of any interest (including Liquidated
Damages, if any) on any Security when it becomes due and payable and such
default continues for a period of 30 days, or

      (b) default is made in the payment of the principal of or premium, if any,
on any Security at the Maturity thereof,

the Company will upon demand of the Trustee pay to it, for the benefit of the
Holders of such Securities, the whole amount then due and payable on such
Securities for principal, premium, if any, and interest (including Liquidated
Damages, if any), and, to the extent permitted by applicable law, any overdue
interest at the rate then in effect, and in addition thereto, such further
amount as shall be sufficient to cover the reasonable costs and expenses of
collection, including the reasonable compensation, expenses, disbursements and
advances of the Trustee, its agents and its counsel.

                                      -31-
<PAGE>

      If the Company fails to pay such amounts forthwith upon such demand, the
Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, may
prosecute such proceeding to judgment or final decree and may enforce the same
against the Company or any other obligor upon the Securities and collect the
monies adjudged or decreed to be payable in the manner provided by law out of
the property of the Company or any other obligor upon the Securities, wherever
situated.

      If an Event of Default occurs and is continuing, the Trustee may in its
discretion proceed to protect and enforce its rights and the rights of the
Holders of Securities by such appropriate judicial proceedings as the Trustee
shall deem most effective to protect and enforce any such rights, whether for
the specific enforcement of any covenant or agreement in this Indenture or in
aid of the exercise of any power granted herein, or to enforce any other proper
remedy.

SECTION 4.4 Trustee May File Proofs of Claim.

      In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relating to the Company or any other obligor upon the
Securities or the property of the Company or of such other obligor or the
creditors of either, the Trustee (whether or not the principal of, and any
interest on, the Securities shall then be due and payable as therein expressed
or by declaration or otherwise and whether or not the Trustee shall have made
any demand on the Company for the payment of overdue principal or interest)
shall be entitled and empowered, by intervention in such proceeding or
otherwise,

      (a) to file and prove a claim for the whole amount of principal, premium,
if any, and interest (including Liquidated Damages, if any) owing and unpaid in
respect of the Securities and take such other actions, including participating
as a member, voting or otherwise, of any official committee of creditors
appointed in such matter, and to file such other papers or documents, in each of
the foregoing cases, as may be necessary or advisable in order to have the
claims of the Trustee (including any claim for the reasonable compensation,
expenses, disbursements and advances of the Trustee, its agents and its counsel)
and of the Holders of Securities allowed in such judicial proceeding, and

      (b) to collect and receive any moneys or other property payable or
deliverable on any such claim and to distribute the same; and any custodian,
receiver, assignee, trustee, liquidator, sequestrator or other similar official
in any such judicial proceeding is hereby authorized by each Holder of
Securities to make such payments to the Trustee and, in the event that the
Trustee shall consent to the making of such payments directly to the Holders of
Securities, to pay to the Trustee any amount due to it for the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and its counsel and any other amounts due the Trustee under Section 5.7.

      Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder of a Security
any plan of reorganization, arrangement, adjustment or composition affecting the
Securities or the rights of any Holder thereof or to authorize the Trustee to
vote in respect of the claim of any Holder of a Security in

                                      -32-
<PAGE>

any such proceeding; provided, however, that the Trustee may, on behalf of such
Holders, vote for the election of a trustee in bankruptcy or similar official.

SECTION 4.5 Trustee May Enforce Claims without Possession of Securities.

      All rights of action and claims under this Indenture or the Securities may
be prosecuted and enforced by the Trustee without the possession of any of the
Securities or the production thereof in any proceeding relating thereto, and any
such proceeding instituted by the Trustee shall be brought in its own name as
trustee of an express trust, and any recovery of judgment shall, after provision
for the payment of the reasonable compensation, expenses, disbursements and
advances of the Trustee, its agents and its counsel, be for the ratable benefit
of the Holders of the Securities in respect of which judgment has been
recovered.

SECTION 4.6 Application of Money Collected.

      Subject to Article Eleven, any money collected by the Trustee pursuant to
this Article Four shall be applied in the following order, at the date or dates
fixed by the Trustee and, in case of the distribution of such money on account
of principal, premium, if any, or interest, upon presentation of the Securities
and the notation thereon of the payment if only partially paid and upon
surrender thereof if fully paid:

      FIRST: To the payment of all amounts due the Trustee under Section 5.7;

      SECOND: To the payment of the amounts then due and unpaid for principal
of, premium, if any, or interest (including Liquidated Damages, if any) on, the
Securities in respect of which or for the benefit of which such money has been
collected, ratably, without preference or priority of any kind, according to the
amounts due and payable on such Securities for principal, premium, if any, and
interest (including Liquidated Damages, if any), respectively; and

      THIRD: Any remaining amounts shall be repaid to the Company.

SECTION 4.7 Limitation on Suits.

      No Holder of any Security shall have any right to institute any
proceeding, judicial or otherwise, with respect to this Indenture, or for the
appointment of a receiver or trustee, or for any other remedy hereunder, unless:

      (a) such Holder has previously given written notice to the Trustee of a
continuing Event of Default;

      (b) the Holders of not less than 25% in principal amount of the
Outstanding Securities shall have made written request to the Trustee to
institute proceedings in respect of such Event of Default in its own name as
Trustee hereunder;

      (c) such Holder or Holders have furnished to the Trustee indemnity
reasonably satisfactory to it against the costs, expenses and liabilities to be
incurred in compliance with such request;

                                      -33-
<PAGE>

      (d) the Trustee for 60 days after its receipt of such notice, request and
offer of indemnity has failed to institute any such proceeding; and

      (e) the Trustee has not received any direction inconsistent with such
written request from the Holders of a majority of the aggregate principal amount
of the Outstanding Securities during the 60 day period referred to in (d) above;

it being understood and intended that no one or more of such Holders shall have
any right in any manner whatever by virtue of, or by availing of, any provision
of this Indenture to affect, disturb or prejudice the rights of any other of
such Holders, or to obtain or seek to obtain priority or preference over any
other of such Holders or to enforce any right under this Indenture, except in
the manner herein provided and for the equal and ratable benefit of all such
Holders.

SECTION 4.8 Unconditional Right of Holders to Receive Principal, Premium and
            Interest and to Convert.

      Notwithstanding any other provision in this Indenture, the Holder of any
Security shall have the right, which is absolute and unconditional, to receive
payment of the principal of, premium, if any, and (subject to Section 2.8)
interest (including Liquidated Damages, if any) on such Security on the
respective Stated Maturities expressed in such Security (or, in the case of
redemption or repurchase, on the Redemption Date or Change in Control Purchase
Date, as the case may be), and to convert such Security in accordance with
Article Ten, and to institute suit for the enforcement of any such payment and
right to convert, and such rights shall not be impaired without the consent of
such Holder.

SECTION 4.9 Restoration of Rights and Remedies.

      If the Trustee or any Holder of a Security has instituted any proceeding
to enforce any right or remedy under this Indenture and such proceeding has been
discontinued or abandoned for any reason, or has been determined adversely to
the Trustee or to such Holder, then and in every such case, subject to any
determination in such proceeding, the Company, the Trustee and the Holders of
Securities shall be restored severally and respectively to their former
positions hereunder and thereafter all rights and remedies of the Trustee and
such Holders shall continue as though no such proceeding had been instituted.

SECTION 4.10 Rights and Remedies Cumulative.

      Except as otherwise provided with respect to the replacement or payment of
mutilated, destroyed, lost or stolen Securities in the last paragraph of Section
2.7, no right or remedy herein conferred upon or reserved to the Trustee or to
the Holders of Securities is intended to be exclusive of any other right or
remedy, and every right and remedy shall, to the extent permitted by law, be
cumulative and in addition to every other right and remedy given hereunder or
now or hereafter existing at law or in equity or otherwise. The assertion or
employment of any right or remedy hereunder, or otherwise, shall not prevent the
concurrent assertion or employment of any other appropriate right or remedy.

                                      -34-
<PAGE>

SECTION 4.11 Delay or Omission Not Waiver.

      No delay or omission of the Trustee or of any Holder of any Security to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or any
acquiescence therein. Every right and remedy given by this Article Four or by
law to the Trustee or to the Holders of Securities may be exercised from time to
time, and as often as may be deemed expedient, by the Trustee or (subject to the
limitations contained in this Indenture) by the Holders of Securities, as the
case may be.

SECTION 4.12 Control by Holders of Securities.

      The Holders of a majority in principal amount of the Outstanding
Securities shall have the right to direct the time, method and place of
conducting any proceeding for any remedy available to the Trustee or exercising
any trust or power conferred on the Trustee, provided that

      (a) such direction shall not be in conflict with any rule of law or with
this Indenture,

      (b) the Trustee may take any other action deemed proper by the Trustee
that is not inconsistent with such direction, and

      (c) such Holders shall have offered to the Trustee security or indemnity
reasonably satisfactory to it against the costs, expenses and liabilities that
might be incurred by it in compliance with such request or direction.

SECTION 4.13 Waiver of Past Defaults.

      The Holders, either (a) through the written consent of not less than a
majority in principal amount of the Outstanding Securities or (b) by the
adoption of a resolution, at a meeting of Holders of the Outstanding Securities
at which a quorum is present, by the Holders of at least a majority in principal
amount of the Outstanding Securities represented at such meeting, may on behalf
of the Holders of all the Securities waive any past default hereunder and its
consequences, except a default (1) in the payment of the principal of, premium,
if any, interest (including Liquidated Damages, if any) or the Change in Control
Price (if applicable), on any Security or (2) in respect of a covenant or
provision hereof that under Article Seven cannot be modified or amended without
the consent of the Holder of each Outstanding Security affected.

      Upon any such waiver, such default shall cease to exist, and any Event of
Default arising therefrom shall be deemed to have been cured, for every purpose
of this Indenture; but no such waiver shall extend to any subsequent or other
default or impair any right consequent thereon.

SECTION 4.14 Undertaking for Costs.

      All parties to this Indenture agree, and each Holder of any Security by
his acceptance thereof shall be deemed to have agreed, that any court may in its
discretion require, in any suit for the enforcement of any right or remedy under
this Indenture, or in any suit against the Trustee for any action taken,
suffered or omitted by it as Trustee, the filing by any party litigant in such
suit of an undertaking to pay the costs of such suit, and that such court may in
its discretion assess reasonable costs, including reasonable attorneys' fees and
expenses, against any party

                                      -35-
<PAGE>

litigant in such suit, having due regard to the merits and good faith of the
claims or defenses made by such party litigant; but the provisions of this
Section 4.14 shall not apply to any suit instituted by the Company, to any suit
instituted by the Trustee, to any suit instituted by any Holder, or group of
Holders, holding in the aggregate more than 10% in principal amount of the
Outstanding Securities, or to any suit instituted by any Holder of any Security
for the enforcement of the payment of the principal of, premium, if any, or
interest (including Liquidated Damages, if any) on any Security on or after the
respective Stated Maturity or Maturities expressed in such Security (or, in the
case of redemption or repurchase, on or after the Redemption Date or Change in
Control Purchase Date, as the case may be) or for the enforcement of the right
to convert any Security in accordance with Article Ten.

SECTION 4.15 Waiver of Stay, Usury or Extension Laws.

      The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, or plead, or in any manner whatsoever claim or
take the benefit or advantage of, any stay, usury or extension law wherever
enacted, now or at any time hereafter in force, that may affect the covenants or
the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede by reason of such law the
execution of any power herein granted to the Trustee but will suffer and permit
the execution of every such power as though no such law had been enacted.

                                  ARTICLE FIVE

                                   THE TRUSTEE

SECTION 5.1 Certain Duties and Responsibilities.

      (a) Except during the continuance of an Event of Default,

            (1) the Trustee undertakes to perform such duties and only such
      duties as are specifically set forth in this Indenture, and no implied
      covenants or obligations shall be read into this Indenture against the
      Trustee; and

            (2) in the absence of bad faith on its part, the Trustee may
      conclusively rely, as to the truth of the statements and the correctness
      of the opinions expressed therein, upon certificates or opinions furnished
      to the Trustee and conforming to the requirements of this Indenture; but
      in the case of any such certificates or opinions that by any provision
      hereof are specifically required to be furnished to the Trustee, the
      Trustee shall be under a duty to examine the same to determine whether or
      not they conform to the requirements of this Indenture but not to verify
      the contents thereof.

      (b) In case an Event of Default has occurred and is continuing, the
Trustee shall exercise such of the rights and powers vested in it by this
Indenture, and use the same degree of care and skill in their exercise, as a
prudent individual would exercise or use under the circumstances in the conduct
of his other own affairs.

                                      -36-
<PAGE>

      (c) No provision of this Indenture shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act, or its own willful misconduct, except that

            (1) this paragraph (c) shall not be construed to limit the effect of
      paragraph (a) of this Section 5.1;

            (2) the Trustee shall not be liable for any error of judgment made
      in good faith by a Responsible Officer, unless it shall be proved that the
      Trustee was negligent in ascertaining the pertinent facts;

            (3) the Trustee shall not be liable with respect to any action taken
      or omitted to be taken by it in good faith in accordance with the
      direction of the Holders of a majority in principal amount of the
      Outstanding Securities relating to the time, method and place of
      conducting any proceeding for any remedy available to the Trustee, or
      exercising any trust or power conferred upon the Trustee, under this
      Indenture; and

            (4) no provision of this Indenture shall require the Trustee to
      expend or risk its own funds or otherwise incur any financial liability in
      the performance of any of its duties hereunder, or in the exercise of any
      of its rights or powers, if it shall have reasonable grounds for believing
      that repayment of such funds or adequate indemnity against such risk or
      liability is not reasonably assured to it.

      (d) Whether or not therein expressly so provided, every provision of this
Indenture relating to the conduct or affecting the liability of or affording
protection to the Trustee shall be subject to the provisions of this Section
5.1.

SECTION 5.2 Notice of Defaults.

      Within 90 days after the occurrence of any default hereunder as to which a
Responsible Officer of the Trustee has actually received written notice, the
Trustee shall give to all Holders of Securities, in the manner provided in
Section 1.6, notice of such default, unless such default shall have been cured
or waived; provided, however, that, except in the case of a default in the
payment of the principal of, premium, if any, or interest (including Liquidated
Damages, if any) on any Security, the Trustee shall be protected in withholding
such notice if and so long as the board of directors, the executive committee or
a trust committee of directors or Responsible Officers of the Trustee in good
faith determine that the withholding of such notice is in the interest of the
Holders. For the purpose of this Section 5.2, the term "default" means any event
that is, or after notice or lapse of time or both would become, an Event of
Default.

SECTION 5.3 Certain Rights of Trustee.

      Subject to the provisions of Section 5.1:

      (a) the Trustee may conclusively rely and shall be fully protected in
acting or refraining from acting upon any resolution, Officers' Certificate,
other certificate, statement, instrument, opinion, report, notice, request,
direction, consent, order, bond, debenture, note,

                                      -37-
<PAGE>

coupon, other evidence of indebtedness or other paper or document believed by it
to be genuine and to have been signed or presented by the proper party or
parties;

      (b) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by a Company Request or Company Order and any resolution
of the Board of Directors shall be sufficiently evidenced by a Board Resolution;

      (c) whenever in the administration of this Indenture the Trustee shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, the Trustee (unless other evidence
be herein specifically prescribed) may, in the absence of bad faith on its part,
rely upon an Officers' Certificate;

      (d) the Trustee may consult with counsel of its selection and the advice
of such counsel or any Opinion of Counsel shall be full and complete
authorization and protection in respect of any action taken, suffered or omitted
by it hereunder in good faith and in reliance thereon;

      (e) the Trustee shall be under no obligation to exercise any of the rights
or powers vested in it by this Indenture at the request or direction of any of
the Holders of Securities pursuant to this Indenture, unless such Holders shall
have offered to the Trustee security or indemnity reasonably satisfactory to it
against the costs, expenses and liabilities that might be incurred by it in
compliance with such request or direction;

      (f) the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, debenture,
note, coupon, other evidence of indebtedness or other paper or document, but the
Trustee may make such further inquiry or investigation into such facts or
matters as it may see fit, and, if the Trustee shall determine to make such
further inquiry or investigation, it shall be entitled to examine the books,
records and premises of the Company, personally or by agent or attorney at the
expense of the Company and shall incur no liability of any kind by reason of
such inquiry or investigation;

      (g) the Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through agents or
attorneys, and the Trustee shall not be responsible for any misconduct or
negligence on the part of any agent or attorney appointed with due care by it
hereunder;

      (h) in no event shall the Trustee be responsible or liable for special,
indirect or consequential loss or damage of any kind whatsoever (including, but
not limited to, loss of profit), irrespective of whether the Trustee has been
advised of the likelihood of such loss or damage and regardless of the form of
action;

      (i) the Trustee shall not be deemed to have notice of any Default or Event
of Default unless a Responsible Officer of the Trustee has actual knowledge
thereof or unless written notice of any event which is in fact such a default is
received by the Trustee at the Corporate Trust Office of the Trustee, and such
notice references the Securities and this Indenture; and

                                      -38-
<PAGE>

      (j) the rights, privileges, protections, immunities and benefits given to
the Trustee, including, without limitation, its right to be indemnified, are
extended to, and shall be enforceable by, the Trustee in each of its capacities
hereunder, and each agent, custodian and other Person employed to act hereunder.

SECTION 5.4 Not Responsible for Recitals or Issuance of Securities.

      The recitals contained herein and in the Securities (except the Trustee's
certificates of authentication) shall be taken as the statements of the Company,
and the Trustee assumes no responsibility for their correctness. The Trustee
makes no representations as to the validity or sufficiency of this Indenture, of
the Securities or of the Common Stock issuable upon the conversion of the
Securities. The Trustee shall not be accountable for the use or application by
the Company of Securities or the proceeds thereof.

SECTION 5.5 May Hold Securities, Act as Trustee under Other Indentures.

      The Trustee, any Authenticating Agent, any Paying Agent, any Conversion
Agent or any other agent of the Company or the Trustee, in its individual or any
other capacity, may become the owner or pledgee of Securities and may otherwise
deal with the Company with the same rights it would have if it were not Trustee,
Authenticating Agent, Paying Agent, Conversion Agent or such other agent.

      The Trustee may become and act as trustee under other indentures under
which other securities, or certificates of interest or participation in other
securities, of the Company are outstanding in the same manner as if it were not
Trustee hereunder.

SECTION 5.6 Money Held in Trust.

      Money held by the Trustee in trust hereunder need not be segregated from
other funds except to the extent required by law. The Trustee shall be under no
liability for interest on any money received by it hereunder, except as
otherwise agreed in writing with the Company.

SECTION 5.7 Compensation and Reimbursement.

      The Company agrees:

      (a) to pay to the Trustee from time to time such reasonable compensation
as the Company and the Trustee shall from time to time agree in writing for all
services rendered by it hereunder (which compensation shall not be limited by
any provision of law in regard to the compensation of a trustee of an express
trust);

      (b) to reimburse the Trustee upon its request for all reasonable expenses,
disbursements and advances incurred or made by the Trustee in accordance with
any provision of this Indenture (including the reasonable compensation and the
expenses and disbursements of its agents and counsel), except any such expense,
disbursement or advance as shall be determined to have been caused by its own
negligence or willful misconduct; and

                                      -39-
<PAGE>

      (c) to fully indemnify the Trustee (and its directors, officers, employees
and agents) for, and to hold it harmless against, any and all loss, damage,
claim, liability or expense, including taxes (other than taxes based on the
income of the Trustee), incurred without negligence or willful misconduct on its
part, arising out of or in connection with the acceptance or administration of
this trust, including the reasonable costs, expenses and reasonable attorneys'
fees and expenses of defending itself against any claim or liability in
connection with the exercise or performance of any of its powers or duties
hereunder.

      When the Trustee incurs expenses or renders services in connection with an
Event of Default specified in Section 4.1(f) or Section 4.1(g) with respect to
the Company, the expenses (including the reasonable charges of its counsel) and
the compensation for the services are intended to constitute expenses of the
administration under any applicable federal or state bankruptcy, insolvency or
other similar law.

      The Trustee shall have a lien prior to the Securities as to all property
and funds held by it hereunder for any amount owing it or any predecessor
Trustee pursuant to this Section 5.7, except with respect to funds held in trust
for the benefit of the Holders of particular Securities.

      The provisions of this Section 5.7 shall survive the termination of this
Indenture or the earlier resignation or removal of the Trustee.

SECTION 5.7 Corporate Trustee Required; Eligibility.

      There shall at all times be a Trustee hereunder which shall be a Person
that is eligible pursuant to the Trust Indenture Act to act as such, having a
combined capital and surplus (or for such purposes, the combined capital and
surplus of any parent holding company) of at least U.S. $25,000,000, subject to
supervision or examination by federal or state authority, in good standing and
having an established place of business or agency in the Borough of Manhattan,
The City of New York. If such corporation publishes reports of condition at
least annually, pursuant to law or to the requirements of said supervising or
examining authority, then for the purposes of this Section 5.8, the combined
capital and surplus of such corporation shall be deemed to be its combined
capital and surplus as set forth in its most recent report of condition so
published. If at any time the Trustee shall cease to be eligible in accordance
with the provisions of this Section 5.8, it shall resign immediately in the
manner and with the effect hereinafter specified in this Article Five and a
successor shall be appointed pursuant to Section 5.9.

SECTION 5.8 Resignation and Removal; Appointment of Successor.

      (a) No resignation or removal of the Trustee and no appointment of a
successor Trustee pursuant to this Article Five shall become effective until the
acceptance of appointment by the successor Trustee in accordance with the
applicable requirements of Section 5.10.

      (b) The Trustee may resign at any time by giving written notice thereof to
the Company. If the instrument of acceptance by a successor Trustee required by
Section 5.10 shall not have been delivered to the Trustee within 30 days after
the giving of such notice of resignation, the resigning Trustee or the Company
may petition at the expense of the Company any court of competent jurisdiction
for the appointment of a successor Trustee.

                                      -40-
<PAGE>

      (c) The Trustee may be removed at any time by Act of the Holders of a
majority in principal amount of the Outstanding Securities, delivered to the
Trustee and the Company. If the instrument of acceptance by a successor Trustee
required by Section 5.10 shall not have been delivered to the Trustee within 30
days after the giving of such notice of removal, the removed Trustee or the
Company may petition at the expense of the Company any court of competent
jurisdiction for the appointment of a successor Trustee.

      (d) If at any time:

            (1) the Trustee shall cease to be eligible under Section 5.8 and
      shall fail to resign after written request therefor by the Company or by
      any Holder of a Security who has been a bona fide Holder of a Security for
      at least six months, or

            (2) the Trustee shall become incapable of acting or shall be
      adjudged a bankrupt or insolvent or a receiver of the Trustee or of its
      property shall be appointed or any public officer shall take charge or
      control of the Trustee or of its property or affairs for the purpose of
      rehabilitation, conservation or liquidation,

then, (i) in any such case the Company may remove the Trustee, or (ii) in the
case of clause (d)(1) above only and subject to Section 4.14, any Holder of a
Security who has been a bona fide Holder of a Security for at least six months
may, on behalf of himself and all others similarly situated, petition any court
of competent jurisdiction for the removal of the Trustee and the appointment of
a successor Trustee.

      (e) If the Trustee shall resign, be removed or become incapable of acting,
or if a vacancy shall occur in the office of Trustee for any cause, the Company
shall promptly appoint a successor Trustee and shall comply with the applicable
requirements of this Section 5.9 and Section 5.10. If, within one year after
such resignation, removal or incapability, or occurrence of such vacancy, a
successor Trustee shall be appointed by Act of the Holders of a majority in
principal amount of the Outstanding Securities delivered to the Company and the
retiring Trustee, the successor Trustee so appointed shall, forthwith upon its
acceptance of such appointment in accordance with the applicable requirements of
Section 5.10, become the successor Trustee and supersede the successor Trustee
appointed by the Company. If no successor Trustee shall have been so appointed
by the Company or the Holders of Securities and accepted appointment in the
manner required by this Section 5.9 and Section 5.10, any Holder of a Security
who has been a bona fide Holder of a Security for at least six months may, on
behalf of himself and all others similarly situated, petition any court of
competent jurisdiction for the appointment of a successor Trustee.

      (f) The successor Trustee shall give notice of each resignation and each
removal of the Trustee and each appointment of a successor Trustee to all
Holders of Securities in the manner provided in Section 1.6. Each notice shall
include the name of the successor Trustee and the address of its Corporate Trust
Office.

                                      -41-
<PAGE>

SECTION 5.9 Acceptance of Appointment by Successor.

      Every successor Trustee appointed hereunder shall execute, acknowledge and
deliver to the Company and to the retiring Trustee an instrument accepting such
appointment, and thereupon the resignation or removal of the retiring Trustee
shall become effective and such successor Trustee, without any further act, deed
or conveyance, shall become vested with all the rights, powers, trusts and
duties of the retiring Trustee. Such retiring Trustee shall, upon payment of its
charges, promptly execute and deliver an instrument transferring to such
successor Trustee all the rights, powers and trusts of the retiring Trustee and
shall duly assign, transfer and deliver to such successor Trustee all property
and money held by such retiring Trustee hereunder. Upon request of any such
successor Trustee, the Company shall execute any and all instruments for more
fully and certainly vesting in and confirming to such successor Trustee all such
rights, powers and trusts.

      No successor Trustee shall accept its appointment unless at the time of
such acceptance such successor Trustee shall be eligible under this Article
Five.

SECTION 5.10 Merger, Conversion, Consolidation or Succession to Business.

      Any corporation into which the Trustee may be merged or converted or with
which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of the Trustee (including the administration of the trust created by
this Indenture), shall be the successor of the Trustee hereunder (provided such
corporation shall be otherwise eligible under this Article Five), without the
execution or filing of any paper or any further act on the part of any of the
parties hereto. In case any Securities shall have been authenticated, but not
delivered, by the Trustee then in office, any successor by merger, conversion or
consolidation to such authenticating Trustee may adopt such authentication and
deliver the Securities so authenticated with the same effect as if such
successor Trustee had itself authenticated such Securities.

SECTION 5.11 Authenticating Agents.

      The Trustee may, with the consent of the Company, appoint an
Authenticating Agent or Agents acceptable to the Company with respect to the
Securities, which shall be authorized to act on behalf of the Trustee to
authenticate Securities issued upon exchange or substitution pursuant to this
Indenture.

      Securities authenticated by an Authenticating Agent shall be entitled to
the benefits of this Indenture and shall be valid and obligatory for all
purposes as if authenticated by the Trustee hereunder, and every reference in
this Indenture to the authentication and delivery of Securities by the Trustee
or the Trustee's certificate of authentication shall be deemed to include
authentication and delivery on behalf of the Trustee by an Authenticating Agent
and a certificate of authentication executed on behalf of the Trustee by an
Authenticating Agent. Each Authenticating Agent shall be subject to acceptance
by the Company and shall at all times be a corporation organized and doing
business under the laws of the United States of America, any state thereof or
the District of Columbia, authorized under such laws to act as Authenticating

                                      -42-
<PAGE>

Agent and subject to supervision or examination by government or other fiscal
authority. If at any time an Authenticating Agent shall cease to be eligible in
accordance with the provisions of this Section 5.12, such Authenticating Agent
shall resign immediately in the manner and with the effect specified in this
Section 5.12.

      Any corporation into which an Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which such Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency or
corporate trust business of an Authenticating Agent, shall continue to be an
Authenticating Agent (provided such corporation shall be otherwise eligible
under this Section 5.12), without the execution or filing of any paper or any
further act on the part of the Trustee or the Authenticating Agent.

      An Authenticating Agent may resign at any time by giving written notice
thereof to the Trustee and to the Company. The Trustee may at any time terminate
the agency of an Authenticating Agent by giving written notice thereof to such
Authenticating Agent and to the Company. Upon receiving such a notice of
resignation or upon such a termination, or in case at any time such
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section 5.12, the Trustee may appoint a successor
Authenticating Agent, which shall be subject to acceptance by the Company. Any
successor Authenticating Agent, upon acceptance of its appointment hereunder,
shall become vested with all the rights, powers and duties of its predecessor
hereunder, with like effect as if originally named as an Authenticating Agent.
No successor Authenticating Agent shall be appointed unless eligible under the
provisions of this Section 5.12.

      The Company agrees to pay to each Authenticating Agent from time to time
reasonable compensation for its services under this Section 5.12.

      If an Authenticating Agent is appointed with respect to the Securities
pursuant to this Section 5.12, the Securities may have endorsed thereon, in
addition to or in lieu of the Trustee's certification of authentication, an
alternative certificate of authentication in the following form:

      This is one of the Securities referred to in the within-mentioned
Indenture.

      By: ___________________________,
      as Authenticating Agent

      By ____________________________
             Authorized Signature

                                      -43-
<PAGE>

SECTION 5.12 Disqualification; Conflicting Interests.

      If the Trustee has or shall acquire a conflicting interest within the
meaning of the Trust Indenture Act, the Trustee shall either eliminate such
interest or resign as Trustee hereunder, to the extent and in the manner
provided by, and subject to the provisions of, the Trust Indenture Act and this
Indenture.

SECTION 5.13 Preferential Collection of Claims Against Company.

      If and when the Trustee shall be or become a creditor of the Company (or
any other obligor upon the Securities), the Trustee shall be subject to the
provisions of the Trust Indenture Act regarding the collection of claims against
the Company (or any such other obligor).

                                  ARTICLE SIX

              CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

SECTION 6.1 Company May Consolidate, Etc., Only on Certain Terms.

      Without the consent or affirmative vote of the Holders of each Outstanding
Security, the Company shall not consolidate with or merge into any other Person
or convey, transfer, sell or lease (other than a grant of security interest) its
properties and assets substantially as an entirety to any Person, and the
Company shall not permit any Person to consolidate with or merge into it or
convey, transfer, sell or lease (other than a grant of security interest) such
Person's properties and assets substantially as an entirety to it, unless:

      (a) the Company is the surviving person or the Person formed by such
consolidation or into which the Company is merged, or the Person to which the
Company's properties and assets are conveyed, transferred, sold or leased (other
than a grant of security interest), shall be a corporation, limited liability
company, partnership or trust organized and validly existing under the laws of
the United States of America, any state thereof or the District of Columbia and,
if other than the Company, shall expressly assume, by an indenture supplemental
hereto, executed and delivered to the Trustee, in form reasonably satisfactory
to the Trustee, the due and punctual payment of the principal of, premium, if
any, and interest (including Liquidated Damages, if any) on all of the
Securities as applicable, and the performance or observance of every covenant of
this Indenture on the part of the Company to be performed or observed;

      (b) immediately after giving effect to such transaction, no Event of
Default, and no event that, after notice or lapse of time or both, would become
an Event of Default, shall have occurred and be continuing; and

      (c) the Company has delivered to the Trustee an Officers' Certificate and
an Opinion of Counsel, each stating that such consolidation, merger, conveyance,
transfer or lease (other than a grant of security interest) and, if a
supplemental indenture is required in connection with such transaction, such
supplemental indenture, comply with this Article Six and that all conditions
precedent herein provided for relating to such transaction have been complied
with, together with any documents required under Section 7.3.

                                      -44-
<PAGE>

SECTION 6.2 Successor Substituted.

      Upon any consolidation of the Company with, or merger of the Company into,
any other Person or any conveyance, transfer or lease (other than a grant of
security interest) of all or substantially all the properties and assets of the
Company in accordance with Section 6.1, the successor Person formed by such
consolidation or into which the Company is merged or to which such conveyance,
transfer or lease (other than a grant of security interest) is made shall
succeed to, and be substituted for, and may exercise every right and power of,
the Company under this Indenture with the same effect as if such successor
Person had been named as the Company herein, and thereafter, except in the case
of a lease, the predecessor Person shall be relieved of all obligations and
covenants under this Indenture and the Securities, except in the case of a lease
or with respect to any obligations that arise from, or are related to, such
transaction.

                                 ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

SECTION 7.1 Supplemental Indentures without Consent of Holders of Securities

      Without the consent of any Holders of Securities, the Company, when
authorized by a Board Resolution, and the Trustee, at any time and from time to
time, may enter into one or more indentures supplemental hereto for any of the
following purposes:

      (a) to evidence the succession of another Person to the Company and the
assumption by any such successor of the covenants and obligations of the Company
herein and in the Securities as permitted by this Indenture; or

      (b) to add to the covenants of the Company for the benefit of the Holders
of Securities or to surrender any right or power herein conferred upon the
Company; or

      (c) to secure the Securities; or

      (d) to make provision with respect to the conversion rights of Holders of
Securities pursuant to Section 10.11; or

      (e) to make any changes or modifications to this Indenture necessary in
connection with the registration of any Registrable Securities under the
Securities Act as contemplated by the Purchase Agreements (provided such action
pursuant to this clause (e) shall not, in the good faith judgment of the
Company, adversely affect the interests of the Holders of Securities in any
respect); or

      (f) to comply with the requirements of the Trust Indenture Act or the
rules and regulations of the Commission thereunder in order to effect or
maintain the qualification of this Indenture under the Trust Indenture Act, as
contemplated by this Indenture or otherwise; or

      (g) to evidence and provide for the acceptance of appointment hereunder by
a successor Trustee;

                                      -45-
<PAGE>

      (h) to provide for uncertificated Securities; or

      (i) to cure any ambiguity, to correct or supplement any provision herein
that may be inconsistent with any other provision herein or that is otherwise
defective, or to make any other provisions with respect to matters or questions
arising under this Indenture as the Company and the Trustee may deem necessary
or desirable (provided such action pursuant to this clause (i) shall not, in the
good faith judgment of the Company, adversely affect the interests of the
Holders of Securities in any respect).

      Upon Company Request accompanied by a Board Resolution authorizing the
execution of any such supplemental indenture, and subject to and upon receipt by
the Trustee of the documents described in Section 7.3 hereof, the Trustee shall
join with the Company in the execution of any supplemental indenture authorized
or permitted by the terms of this Indenture and to make any further appropriate
agreements and stipulations that may be therein contained.

SECTION 7.2 Supplemental Indentures with Consent of Holders of Securities.

      Except as set forth in Section 7.1, with either (a) the written consent of
the Holders of not less than a majority in principal amount of the Outstanding
Securities, by the Act of said Holders delivered to the Company and the Trustee,
or (b) by the adoption of a resolution, at a meeting of Holders of the
Outstanding Securities at which a quorum is present, by the Holders of a
majority in principal amount of the Outstanding Securities represented at such
meeting, the Company, when authorized by a Board Resolution, and the Trustee may
enter into an indenture or indentures supplemental hereto for the purpose of
adding any provisions to or changing in any manner or eliminating any of the
provisions of this Indenture or of modifying in any manner the rights of the
Holders of Securities under this Indenture; provided, however, that no such
supplemental indenture shall, without the consent or affirmative vote of the
Holder of each Outstanding Security affected thereby,

            (l) change the Stated Maturity of the principal of, or any
      installment of interest on, any Security, or reduce the principal amount,
      any premium or the rate of interest payable thereon, or change the place
      at which or the coin or currency in which any Security or the interest
      (including Liquidated Damages, if any) or any premium thereon or any other
      amount in respect thereof is payable; or

            (2) reduce the amount payable on any Security upon provisional
      redemption at the Company's option pursuant to Article Nine; or

            (3) impair the right to institute suit for the enforcement of any
      payment in respect of any Security on or after the Stated Maturity thereof
      (or, in the case of redemption or any repurchase, on or after the
      Redemption Date or Change in Control Purchase Date, as the case may be) or
      the conversion of any Security; or

            (4) except as permitted by Section 10.11, adversely affect the right
      to convert any Security as provided in Article Ten; or

                                      -46-
<PAGE>

            (5) modify the provisions of this Indenture with respect to the
      subordination of the Securities in a manner adverse to the Holders of any
      Securities; or

            (6) reduce the percentage in principal amount of the Outstanding
      Securities the consent of whose Holders is required for any supplemental
      indenture to modify or amend any provision of this Indenture or the
      consent of whose Holders is required for any waiver (of compliance with
      certain provisions of this Indenture or certain defaults hereunder and
      their consequences) provided for in this Indenture; or

            (7) modify any of the provisions of this Section 7.2 except to
      increase any percentage contained herein or therein or to provide that
      certain other provisions of this Indenture cannot be modified or waived
      without the consent of the Holder of each Outstanding Security affected
      thereby; or

            (8) amend or modify the provisions of Article Twelve regarding the
      Holder's right to require the Company to repurchase the Securities upon a
      Change in Control, in a manner adverse to the Holders.

      It shall not be necessary for any Act of Holders of Securities under this
Section 7.2 to approve the particular form of any proposed supplemental
indenture, but it shall be sufficient if such Act shall approve the substance
thereof.

      The quorum at any meeting called to adopt a resolution shall be Holders
representing a majority in aggregate principal amount of Securities at the time
Outstanding.

SECTION 7.3 Execution of Supplemental Indentures.

      In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article Seven or the modifications
thereby of the trusts created by this Indenture, the Trustee shall be provided
with, and (subject to Sections 5.1 and 5.3) shall be fully protected in relying
upon, an Opinion of Counsel stating that the execution of such supplemental
indenture is authorized or permitted by this Indenture and that such
supplemental indenture has been duly authorized, executed and delivered by the
Company and constitutes a valid and legally binding obligation of the Company
enforceable against the Company in accordance with its terms. The Trustee may,
but shall not be obligated to, enter into any such supplemental indenture that
adversely affects the Trustee's own rights, duties or immunities under this
Indenture or otherwise.

SECTION 7.4 Effect of Supplemental Indentures.

      Upon the execution of any supplemental indenture under this Article Seven,
this Indenture shall be modified in accordance therewith, and such supplemental
indenture shall form a part of this Indenture for all purposes; and every Holder
of Securities theretofore or thereafter authenticated and delivered hereunder
appertaining thereto shall be bound thereby.

                                      -47-
<PAGE>

SECTION 7.5 Reference in Securities to Supplemental Indentures.

      Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article Seven may, and shall if required
by the Trustee, bear a notation in form approved by the Trustee as to any matter
provided for in such supplemental indenture. If the Company shall so determine,
new Securities so modified as to conform, in the opinion of the Company and the
Trustee, to any such supplemental indenture may be prepared and executed by the
Company and authenticated and delivered by the Trustee in exchange for
Outstanding Securities.

SECTION 7.6 Notice of Supplemental Indentures.

      Promptly after the execution by the Company and the Trustee of any
supplemental indenture pursuant to the provisions of Section 7.2, the Company
shall give notice to all Holders of Securities of such fact, setting forth in
general terms the substance of such supplemental indenture, in the manner
provided in Section 1.6. Any failure of the Company to give such notice, or any
defect therein, shall not in any way impair or affect the validity of any such
supplemental indenture.

                                 ARTICLE EIGHT

                                    COVENANTS

SECTION 8.1 Payment of Principal, Premium and Interest.

      The Company covenants and agrees that it will duly and punctually pay the
principal of and premium, if any, and interest (including Liquidated Damages, if
any) on the Securities in accordance with the terms of the Securities and this
Indenture. The Company shall deposit or cause to be deposited with the Trustee
on the date of the Stated Maturity of any Security or on the due date for any
installment of interest, all payments so due, which payments shall be in
immediately available funds on the date of such Stated Maturity or due date, as
the case may be.

SECTION 8.2 Maintenance of Offices or Agencies.

      The Company hereby appoints the Corporate Trust Office or such other
office or agency of the Trustee as its agent in the Borough of Manhattan, The
City of New York, where Securities may be presented or surrendered for payment,
where Securities may be surrendered for registration of transfer or exchange,
where Securities may be surrendered for conversion, and where notices and
demands to or upon the Company in respect of the Securities and this Indenture
may be served.

      The Company may at any time and from time to time vary or terminate the
appointment of any such agent or appoint any additional agents for any or all of
such purposes; provided, however, that until all of the Securities have been
delivered to the Trustee for cancellation, or moneys sufficient to pay the
principal of, premium, if any, and interest (including Liquidated Damages, if
any) on the Securities have been made available for payment and either paid or
returned to the Company pursuant to the provisions of Section 8.3, the Company
shall maintain

                                      -48-
<PAGE>

in the Borough of Manhattan, The City of New York, an office or agency where
Securities may be presented or surrendered for payment and conversion, where
Securities may be surrendered for registration of transfer or exchange and where
notices and demands to or upon the Company in respect of the Securities and this
Indenture may be served. The Company shall give prompt written notice to the
Trustee, and notice to the Holders in accordance with Section 1.6, of the
appointment or termination of any such agents and of the location and any change
in the location of any such office or agency.

      If at any time the Company shall fail to maintain any such required office
or agency, or shall fail to furnish the Trustee with the address thereof,
presentations and surrenders may be made and notices and demands may be served
on the Corporate Trust Office.

SECTION 8.3 Money for Security Payments to Be Held in Trust.

      If the Company will act as its own Paying Agent, it shall, on or before
each due date of the principal of, premium, if any, or interest (including
Liquidated Damages, if any) on any of the Securities, segregate and hold in
trust for the benefit of the Persons entitled thereto a sum sufficient to pay
the principal, premium, if any, or interest (including Liquidated Damages, if
any) so becoming due until such sums shall be paid to such Persons or otherwise
disposed of as herein provided, and the Company will promptly notify the Trustee
of its action or failure so to act.

      Whenever the Company shall have one or more Paying Agents, it will, no
later than on each due date of the principal of, premium, if any, or interest
(including Liquidated Damages, if any) on any Securities, deposit with the
Trustee a sum sufficient to pay the principal, premium, if any, or interest
(including Liquidated Damages, if any) so becoming due, such sum to be held for
the benefit of the Persons entitled to such principal, premium, if any, or
interest, and (unless such Paying Agent is the Trustee) the Company will
promptly notify the Trustee of any failure so to act.

      The Company will cause each Paying Agent other than the Trustee to execute
and deliver to the Trustee an instrument in which such Paying Agent shall agree
with the Trustee, subject to the provisions of this Section 8.3, that such
Paying Agent will:

      (a) hold all sums held by it for the payment of the principal of, premium,
if any, or interest (including Liquidated Damages, if any) on Securities for the
benefit of the Persons entitled thereto until such sums shall be paid to such
Persons or otherwise disposed of as herein provided;

      (b) give the Trustee notice of any default by the Company (or any other
obligor upon the Securities) in the making of any payment of principal, premium,
if any, or interest (including Liquidated Damages, if any); and

      (c) at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held by
such Paying Agent.

      The Company may at any time, for the purpose of obtaining the satisfaction
and discharge of this Indenture or for any other purpose, pay, or by Company
Order direct any

                                      -49-
<PAGE>

Paying Agent to pay, to the Trustee all sums held in trust by the Company or
such Paying Agent, such sums to be held by the Trustee upon the same trusts as
those upon which such sums were held by the Company or such Paying Agent; and,
upon such payment by any Paying Agent to the Trustee, such Paying Agent shall be
released from all further liability with respect to such money.

      Anything contained herein to the contrary notwithstanding, any money held
by the Trustee or any Paying Agent in trust for the payment and discharge of the
principal of, premium, if any, or interest (including Liquidated Damages, if
any) on any Security that remains unclaimed for two years after the date when
each payment of such principal, premium, or interest (including Liquidated
Damages, if any) has become payable shall, upon the request of the Company, be
repaid by the Trustee to the Company as its absolute property free from trust,
and the Trustee shall thereupon be released and discharged with respect thereto
and the Holders shall look only to the Company for the payment of the principal,
premium or interest (including Liquidated Damages, if any) on such Security. The
Trustee shall not be liable to the Company or any Holder for interest on funds
held by it for the payment and discharge of the principal, premium or interest
(including Liquidated Damages, if any) on any of the Securities to any Holder.
The Company shall not be liable for any interest on the sums paid to it pursuant
to this paragraph and shall not be regarded as a trustee of such money.

SECTION 8.4 Existence.

      Subject to Article Six, the Company will do or cause to be done all things
necessary to preserve and keep in full force and effect its corporate existence
and rights (charter and statutory); provided, however, that the Company shall
not be required to preserve any such right if the Board of Directors shall
determine that the preservation thereof is no longer desirable in the conduct of
the business of the Company and that the loss thereof is not disadvantageous in
any material respect to the Holders.

SECTION 8.5 Statement by Officers as to Default.

      The Company shall deliver to the Trustee, within 120 days after the end of
each fiscal year of the Company ending after the date hereof, an Officers'
Certificate (one of the signers of which shall be the Company's principal
executive, principal financial or principal accounting officer), stating whether
or not to the knowledge of the signers thereof the Company is in default in the
performance and observance of any of the terms, provisions and conditions of
this Indenture (without regard to any period of grace or requirement of notice
provided hereunder) and, if the Company shall be in default, specifying all such
defaults and the nature and status thereof of which they have knowledge.

      The Company will deliver to the Trustee, forthwith upon becoming aware of
any default in the performance or observance of any covenant, agreement or
condition contained in this Indenture, or any Event of Default, an Officers'
Certificate specifying with particularity such default or Event of Default and
further stating what action the Company has taken, is taking or proposes to take
with respect thereto.

                                      -50-
<PAGE>

      Any notice required to be given under this Section 8.5 shall be delivered
to the Trustee at the Corporate Trust Office.

SECTION 8.6 Delivery of Certain Information.

      At any time when the Company is not subject to Section 13 or 15(d) of the
Exchange Act, upon the request of a Holder of a Security or the holder of shares
of Common Stock issued upon conversion thereof, the Company will promptly
furnish or cause to be furnished Rule 144A Information to such Holder of
Securities or such holder of shares of Common Stock issued upon conversion of
Securities, or to a prospective purchaser of any such security designated by any
such Holder or holder, as the case may be, to the extent required to permit
compliance by such Holder or holder with Rule 144A under the Securities Act (or
any successor provision thereto) in connection with the resale of any such
security; provided, however, that the Company shall not be required to furnish
such information in connection with any request made on or after the date that
is two years from the later of (a) the date such a security (or any such
predecessor security) was last acquired from the Company or (b) the date such a
security (or any such predecessor security) was last acquired from an
"affiliate" of the Company within the meaning of Rule 144 under the Securities
Act (or any successor provision thereto). "Rule 144A Information" shall be such
information as is specified pursuant to Rule 144A(d) (4) under the Securities
Act (or any successor provision thereto).

                                  ARTICLE NINE

                        PERSONAL REDEMPTION OF SECURITIES

SECTION 9.1 Right of Redemption.

      (a) The Securities may be redeemed in accordance with the provisions of
the form of Securities attached hereto as Exhibit A and as set forth in this
Article Nine. At any time prior to the Stated Maturity, the Company, at its own
option, may redeem the Securities, in whole or in part, in accordance with the
provisions of this Article Nine, and on the Redemption Date for a redemption
price (the "Redemption Price") in cash (except as set forth below) equal to 100%
of the principal amount of the Securities plus accrued and unpaid interest
(including Liquidated Damages, if any) on the Securities to but not including
the Redemption Date plus the Interest Make-Whole Payment; provided, that (1) the
Closing Sale Price of the Common Stock has exceeded 150% of the Conversion Price
then in effect for at least 20 Trading Days within a period of 30 consecutive
Trading Days ending on the Trading Day immediately before the date of mailing of
the Redemption Notice and (2) the Registration Statement covering resale of the
Securities and the Underlying Common Stock (as defined in the Purchase
Agreement) is effective and available for use for the 30 days following the
Redemption Date, unless registration thereof is not required. The Company will
pay Holders any accrued and unpaid interest through the Redemption Date as well
as any Interest Make-Whole Payment with respect to their Securities which are
redeemed, regardless of whether such Securities are converted prior to the
Redemption Date.

      (b) Notwithstanding the foregoing, the Company may make the Interest
Make-Whole Payment in (1) cash, (2) subject to certain conditions set forth
below in this Section 9.1,

                                      -51-
<PAGE>

Common Stock or the common stock (or equivalent equity security) of the
successor Person or parent of the Company after a transaction, in each case,
pursuant to Article Six ("Successor Common Stock"), or (3) a combination of cash
and Common Stock or Successor Common Stock.

      (c) If the Company pays the Interest Make-Whole Payment in shares of
Common Stock or Successor Common Stock, the value of the Common Stock or the
Successor Common Stock to be delivered in respect of the Interest Make-Whole
Payment shall be deemed to be equal to 95% of the average of the Closing Sale
Prices per share for the five consecutive Trading Days ending on and including
the third day prior to the Redemption Date. The Company shall calculate the
amount of any Interest Make-Whole Payment.

      (d) The following are conditions to the Company's election to pay for the
Interest Make-Whole Payment in Common Stock or Successor Common Stock:

            (i) The shares of Common Stock or Successor Common Stock to be
issued upon payment of the Interest Make-Whole Payment:

                  (A) shall not require registration under any federal
securities law before such shares may be freely transferable without being
subject to any transfer restrictions under the Securities Act upon payment or,
if such registration is required, such registration shall be completed and shall
become effective prior to the Redemption Date; and

                  (B) shall not require registration with, or approval of, any
governmental authority under any state law or any other federal law before
shares may be validly issued or delivered upon payment or if such registration
is required or such approval must be obtained, such registration shall be
completed or such approval shall be obtained prior to the Redemption Date.

            (ii) The shares of Common Stock or Successor Common Stock to be
issued upon payment of the Interest Make-Whole Payment hereunder are, or shall
have been, approved for listing on the principal U.S. national securities
exchange on which such Common Stock or Successor Common Stock is then listed or,
if not so listed, on The Nasdaq National Market, in any case, prior to the
Redemption Date.

            (iii) All shares of Common Stock or Successor Common Stock which may
be issued upon payment of the Interest Make-Whole Payment will be issued out of
the Company's authorized but unissued Common Stock or out of the successor's or
parent's (as applicable) authorized but unissued Successor Common Stock and
will, upon issue, be duly and validly issued and fully paid and nonassessable
and free of any preemptive or similar rights.

            (iv) If any of the conditions set forth in clauses (i) through (iii)
of this Section 9.1(d) are not satisfied in accordance with the terms thereof,
the Interest Make-Whole Payment shall be paid by the Company only in cash. The
Company may not change the form of consideration to be paid with respect to the
Interest Make-Whole Payment once it has stated such form in the Redemption
Notice, except as described in the immediately preceding sentence.

                                      -52-
<PAGE>

            The Trustee, subject to the provisions of Section 5.1, shall not at
any time be under any duty or responsibility to any Holder of Securities to
calculate, determine or approve the Redemption Price or the Interest Make-Whole
Payment as described in this Section 9.1

SECTION 9.2 Election to Redeem; Notice to Trustee.

      In case the Company shall desire to exercise the right to redeem all or,
as the case may be, any part of the Securities pursuant to this Article Nine, it
shall fix a date for redemption (the "Redemption Date"). In case of any
redemption at the election of the Company of any of the Securities pursuant to
Section 9.1, the Company shall, at least 35 days prior to the Redemption Date
fixed by the Company (unless a shorter notice shall be satisfactory to the
Trustee), notify the Trustee in writing of such Redemption Date.

SECTION 9.3 Selection by Trustee of Securities to Be Redeemed.

      If less than all the Securities are to be redeemed, the particular
Securities to be redeemed shall be selected by the Trustee at least three
Business Days prior to the date that the notice described in Section 9.4 is
given from the Outstanding Securities not previously called for redemption by
lot or such method as the Trustee may deem fair and appropriate.

      If any Registered Security selected for partial redemption is converted in
part before termination of the conversion right with respect to the portion of
the Security so selected, the converted portion of such Security shall be deemed
(so far as may be) to be the portion selected for redemption (provided, however,
that the Holder of such Security so converted and deemed redeemed shall not be
entitled to any additional interest as a result of such deemed redemption than
such Holder would have otherwise been entitled to receive upon conversion of
such Security). Securities that have been converted during a selection of
Securities to be redeemed may be treated by the Trustee as Outstanding for the
purpose of such selection.

      The Trustee shall promptly notify the Company and each Security Registrar
in writing of the Securities selected for redemption and, in the case of any
Securities selected for partial redemption, the principal amount and certificate
numbers thereof to be redeemed.

      For all purposes of this Indenture, unless the context otherwise requires,
all provisions relating to the redemption of Securities shall relate, in the
case of any Securities redeemed or to be redeemed only in part, to the portion
of the principal amount of such Securities that has been or is to be redeemed.

SECTION 9.4 Notice of Redemption.

      Notice of redemption (the "Redemption Notice") shall be given in the
manner provided in Section 1.6 to the Holders of Securities to be redeemed at
their respective last addresses as the same appears on the Security Register not
less than 30 nor more than 60 days prior to the Redemption Date, and such notice
shall be irrevocable.

      Such mailing shall be by first class mail. The notice, if mailed in the
manner herein provided, shall be conclusively presumed to have been duly given,
whether or not the Holder receives such notice. In any case, failure to give
such notice by mail or any defect in the notice

                                      -53-
<PAGE>

to the Holder of any Security designated for redemption as a whole or in part
shall not affect the validity of the proceedings for the redemption of any other
Security.

      The Redemption Notice shall identify the Securities to be redeemed
(including CUSIP, ISIN or similar numbers) and shall state:

      (a) the Redemption Date,

      (b) the Redemption Price at which the Securities are to be redeemed,
accrued interest, if any and the Interest Make-Whole Payment,

      (c) with respect to the Interest Make-Whole Payment, the form of
consideration to be used to make such payment,

      (d) if less than all Outstanding Securities are to be redeemed, the
aggregate principal amount of Securities to be redeemed,

      (e) that on the Redemption Date the Redemption Price will become due and
payable upon each such Security to be redeemed, and that interest thereon shall
cease to accrue on and after said date,

      (f) the Conversion Rate, the date on which the right to convert the
Securities to be redeemed will terminate and the places where such Securities
may be surrendered for conversion,

      (g) the place or places where such Securities are to be surrendered for
payment of the Redemption Price, and

      (h) with respect to any Security to be redeemed only in part, the portion
of the principal amount to be redeemed and that on and after the Redemption
Date, upon surrender of a Security, a new Security or Securities in principal
amount equal to the unredeemed portion thereof will be issued.

      The Redemption Notice shall be given by the Company or, at the Company's
written request, by the Trustee in the name of and at the expense of the
Company. Any Redemption Notice received by the Trustee shall be given by the
Trustee to each Paying Agent in the name of and at the expense of the Company.

SECTION 9.5 Deposit of Redemption Price.

      On or prior to any Redemption Date, the Company shall deposit with the
Trustee (or, if the Company is acting as its own Paying Agent, segregate and
hold in trust as provided in Section 8.3) an amount of money (which shall be in
immediately available funds on such Redemption Date) sufficient to pay the
Redemption Price of (including accrued interest unless the Redemption Date shall
be an Interest Payment Date) all the Securities that are to be redeemed on that
date other than any Securities called for redemption on that date that have been
converted prior to the date of such deposit, including, if the Company so
elects, shares of Common Stock or Successor Common Stock, with respect to the
Interest Make-Whole Payment.

                                      -54-
<PAGE>

      If any Security called for redemption is converted, any money deposited
with the Trustee or so segregated and held in trust for the redemption of such
Security shall (subject to any right of the Holder or such Security or any
Predecessor Security to receive interest as provided in the last paragraph of
Section 2.8) be paid to the Company or, if then held by the Company, shall be
discharged from such trust.

SECTION 9.6 Securities Payable on Redemption Date.

      Notice of redemption having been given as aforesaid, the Securities to be
so redeemed shall, unless converted into Common Stock, become due and payable on
the Redemption Date at the Redemption Price therein specified, and from and
after such date (unless the Company shall default in the payment of the
Redemption Price, including accrued interest) such Securities shall cease to
bear interest, shall cease to be convertible into Common Stock and, except as
provided in the Securities, to be entitled to any benefit or security under this
Indenture and the Holders thereof shall have no right in respect to such
Securities except the right to receive the Redemption Price thereof. Upon
surrender of any Security for redemption in accordance with said notice, such
Security shall be paid by the Company at the Redemption Price to the Redemption
Date; provided, however, that installments of interest on Securities whose
Stated Maturity is on or prior to the Redemption Date shall be payable to the
Holders of such Securities, or one or more Predecessor Securities, registered as
such on the relevant Record Date according to their terms and the provisions of
Section 2.8.

      If any Security called for redemption shall not be so paid upon surrender
thereof for redemption, the principal amount of, premium, if any, and, to the
extent permitted by applicable law, accrued interest (including Liquidated
Damages, if any) on such Security shall, until paid, bear interest from the
Redemption Date at the rate then in effect, and such Security shall remain
convertible until the principal of such Security (or portion thereof, as the
case may be) shall have been paid or duly provided for.

      Notwithstanding the foregoing, the Trustee shall not redeem any Securities
or mail any Redemption Notices during the continuance of a default in payment of
interest on the Securities. If any Security called for redemption shall not be
so paid upon surrender thereof for redemption, the principal shall, until paid
or duly provided for, continue to bear interest at the rate borne by the
Security, compounded semi-annually, and such Security shall remain convertible
into Common Stock until the principal and interest shall have been paid or duly
provided for. The Company will notify all of the Holders if the Company redeems
any of the Securities.

SECTION 9.7 Securities Redeemed in Part.

      Any Security that is to be redeemed only in part shall be surrendered at
an office or agency of the Company designated for that purpose pursuant to
Section 8.2 (with, if the Company or the Trustee so requires, due endorsement
by, or a written instrument of transfer in form satisfactory to the Company and
the Trustee duly executed by, the Holder thereof or his attorney duly authorized
in writing), and the Company shall execute, and the Trustee shall authenticate
and make available for delivery to the Holder of such Security without service
charge, a new Registered Security or Securities, of any authorized denomination
as requested by

                                      -55-
<PAGE>

such Holder, in aggregate principal amount equal to and in exchange for the
unredeemed portion of the principal of the Security so surrendered.

      If the Company opts to redeem less than all of the Outstanding Securities,
the Trustee shall select or cause to be selected the Securities or portions
thereof of the Global Note or the Securities in certificated form to be redeemed
(in principal amounts of $1,000 or integral multiples thereof) by lot, on a pro
rata basis or by another method the Trustee deems fair and appropriate. If any
Security selected for partial redemption is submitted for conversion in part
after such selection, the portion of such Security submitted for conversion
shall be deemed (so far as may be possible) to be from the portion selected for
redemption. The Securities (or portions thereof) so selected shall be deemed
duly selected for redemption for all purposes hereof, notwithstanding that any
such Security is submitted for conversion in part before the mailing of the
Redemption Notice.

SECTION 9.8 Conversion Arrangement on Call for Redemption.

      In connection with any redemption of the Securities, the Company may
arrange for the purchase and conversion of any Securities by an agreement with
one or more investment bankers or other purchasers (the "Purchasers") to
purchase such Securities by paying to the Trustee in trust for the Holders, on
or before the Redemption Date, an amount not less than the applicable Redemption
Price, together with interest accrued and unpaid to, but excluding, the
Redemption Date (including Liquidated Damages), of such Securities.
Notwithstanding anything to the contrary contained in this Article Nine, the
obligation of the Company to pay the Redemption Price, together with interest
accrued and unpaid to, but excluding, the Redemption Date (including Liquidated
Damages), shall be deemed to be satisfied and discharged to the extent such
amount is so paid by such Purchasers. If such an agreement is entered into (a
copy of which shall be filed with the Trustee prior to the close of business on
the second Business Day immediately prior to the Redemption Date), any
Securities called for redemption that are not duly surrendered for conversion by
the Holders thereof may, at the option of the Company, be deemed, to the fullest
extent permitted by law, and consistent with any agreement or agreements with
such Purchasers, to be acquired by such Purchasers from such Holders and
(notwithstanding anything to the contrary contained in this Article Nine)
surrendered by such Purchasers for conversion, all as of immediately prior to
the close of business on the Redemption Date (and the right to convert any such
Securities shall be extended through such time), subject to payment of the above
amount as aforesaid. At the direction of the Company, the Trustee shall hold and
dispose of any such amount paid to it by the Purchasers to the Holders in the
same manner as it would monies deposited with it by the Company for the
redemption of Securities. Without the Trustee's prior written consent, no
arrangement between the Company and such Purchasers for the purchase and
conversion of any Securities shall increase or otherwise affect any of the
powers, duties, responsibilities or obligations of the Trustee as set forth in
this Indenture, and the Company agrees to indemnify the Trustee from, and hold
it harmless against, any loss, liability or expense arising out of or in
connection with any such arrangement for the purchase and conversion of any
Securities between the Company and such Purchasers, including the costs and
expenses, including reasonable legal fees, incurred by the Trustee in the
defense of any claim or liability arising out of or in connection with the
exercise or performance of any of its powers, duties, responsibilities or
obligations under this Indenture.

                                      -56-
<PAGE>

                                  ARTICLE TEN

                            CONVERSION OF SECURITIES

SECTION 10.1 Conversion Privilege and Conversion Rate.

      Subject to and upon compliance with the provisions of this Article Ten, at
the option of the Holder thereof, any Security or any portion of the principal
amount thereof that is U.S. $l,000 or an integral multiple of U.S. $1,000 may be
converted into fully paid and nonassessable shares (calculated as to each
conversion to the nearest 1/100th of a share) of Common Stock of the Company at
the Conversion Rate, determined as hereinafter provided, in effect at the time
of conversion. Such conversion right shall commence upon the original issuance
of the Securities and expire at the close of business on the Stated Maturity,
unless the Security has been previously redeemed or repurchased, subject, in the
case of conversion of any Global Security, to any Applicable Procedures. In case
a Security or portion thereof is called for redemption at the election of the
Company or the Holder thereof exercises his right to require the Company to
repurchase the Security, such conversion right in respect of the Security, or
portion thereof so called, shall expire at the close of business on the Business
Day immediately preceding the Redemption Date or the Change in Control Purchase
Date, as the case may be, unless the Company defaults in making the payment due
upon redemption or repurchase, as the case may be (in each case subject, as
aforesaid, to any Applicable Procedures with respect to any Global Security).

      The rate at which shares of Common Stock shall be delivered upon
conversion (herein called the "Conversion Rate") shall be initially 67.7507
shares of Common Stock for each U.S. $l,000 principal amount of Securities. The
Conversion Rate shall be adjusted in certain instances as provided in this
Article Ten.

SECTION 10.2 Exercise of Conversion Privilege.

      In order to exercise the conversion privilege, the Holder of any Security
to be converted shall surrender such Security, duly endorsed or assigned to the
Company or in blank, at any office or agency of the Company maintained for that
purpose pursuant to Section 8.2, accompanied by a duly signed and completed
conversion notice substantially in the form attached hereto as Exhibit C stating
that the Holder elects to convert such Security or, if less than the entire
principal amount thereof is to be converted, the portion thereof to be
converted. Each Security surrendered for conversion (in whole or in part) during
the Record Date Period shall (except in the case of any Security or portion
thereof that has been called for redemption on a Redemption Date, or is to be
repurchased on a Change in Control Purchase Date, occurring, in either case
within such Record Date Period and, as a result the conversion right of such
Security would terminate in such period if not exercised, be accompanied by
payment in New York Clearing House funds or other funds acceptable to the
Company of an amount equal to the interest payable on such Interest Payment Date
on the principal amount of such Security (or part thereof, as the case may be)
being surrendered for conversion. The interest so payable on such Interest
Payment Date, with respect to any Security (or portion thereof, if applicable)
that is surrendered for conversion during Record Date Period, shall be paid to
the Holder of such

                                      -57-
<PAGE>

Security as of such Regular Record Date in an amount equal to the interest that
would have been payable on such Security, if such Security had been converted as
of the close of business on such Interest Payment Date. Interest payable in
respect of any Security surrendered for conversion on or after an Interest
Payment Date shall be paid to the Holder of such Security as of the Regular
Record Date next preceding such Interest Payment Date, notwithstanding the
exercise of the right of conversion. Except as provided in this paragraph and
subject to the last paragraph of Section 2.8, no cash payment or adjustment
shall be made upon any conversion on account of any interest accrued from the
Interest Payment Date next preceding the conversion date, in respect of any
Security (or part thereof, as the case may be) surrendered for conversion, or on
account of any dividends on the Common Stock issued upon conversion. The
Company's delivery to the Holder of the number of shares of Common Stock (and
cash in lieu of fractions thereof, as provided in this Indenture) into which a
Security is convertible and any rights and warrants pursuant to Section 10.4(c)
will be deemed to satisfy the Company's obligation to pay the principal amount
of the Security.

      Securities shall be deemed to have been converted on the day of surrender
of such Securities for conversion in accordance with the foregoing provisions,
and at such time the rights of the Holders of such Securities as Holders shall
cease, and the Person or Persons entitled to receive the Common Stock issuable
upon conversion shall be treated for all purposes as the record holder or
holders of such Common Stock at such time. As promptly as practicable on or
after the conversion date, the Company shall issue and deliver to the Trustee,
for delivery to the Holder, a certificate or certificates for the number of full
shares of Common Stock issuable upon conversion, together with payment in lieu
of any fraction of a share, as provided in Section 10.3.

      All shares of Common Stock delivered upon such conversion of Securities
shall bear restrictive legends substantially in the form of the legends required
to be set forth on the Securities pursuant to Section 2.6 and shall be subject
to the restrictions on transfer provided in such legends. Neither the Trustee
nor any agent maintained for the purpose of such conversion shall have any
responsibility for the inclusion or content of any such restrictive legends on
such Common Stock; provided, however, that the Trustee or any agent maintained
for the purpose of such conversion shall have provided to the Company or to the
Company's transfer agent for such Common Stock, prior to or concurrently with a
request to the Company to deliver such Common Stock, written notice that the
Securities delivered for conversion are Restricted Securities.

      In the case of any Security that is converted in part only, upon such
conversion the Company shall execute and the Trustee shall authenticate and make
available for delivery to the Holder thereof, at the expense of the Company, a
new Security or Securities of authorized denominations in an aggregate principal
amount equal to the unconverted portion of the principal amount of such
Security. A Security may be converted in part, but only if the principal amount
of such Security to be converted is any integral multiple of U.S. $1,000 and the
principal amount of such security to remain Outstanding after such conversion is
equal to U.S. $l,000 or any integral multiple of U.S. $l,000 in excess thereof.

SECTION 10.3 Fractions of Shares.

      No fractional shares of Common Stock shall be issued upon conversion of
any Security or Securities. If more than one Security shall be surrendered for
conversion at one time by the

                                      -58-
<PAGE>

same Holder, the number of full shares that shall be issuable upon conversion
thereof shall be computed on the basis of the aggregate principal amount of the
Securities (or specified portions thereof) so surrendered. Instead of any
fractional share of Common Stock that would otherwise be issuable upon
conversion of any Security or Securities (or specified portions thereof), the
Company shall calculate and pay a cash adjustment in respect of such fraction
(calculated to the nearest 1/100th of a share) in an amount equal to the same
fraction of the Closing Sale Price at the close of business on the day of
conversion.

SECTION 10.4 Adjustment of Conversion Rate.

      The Conversion Rate shall be subject to adjustment from time to time as
follows:

            (a) In case the Company shall (1) pay a dividend in shares of Common
Stock to all holders of Common Stock, (2) make a distribution in shares of
Common Stock to all holders of Common Stock, (3) subdivide the outstanding
shares of Common Stock into a greater number of shares of Common Stock, (4)
combine the outstanding shares of Common Stock into a smaller number of shares
of Common Stock or (5) otherwise reclassify the outstanding shares of Common
Stock, the Conversion Rate in effect immediately prior to such action shall be
adjusted so that the Holder of any Security thereafter surrendered for
conversion shall be entitled to receive the number of shares of Common Stock
which such Holder would have owned immediately following such action had such
Securities been converted immediately prior thereto. Any adjustment made
pursuant to this Section 10.4(a) shall become effective immediately after the
record date in the case of a dividend or distribution and shall become effective
immediately after the effective date in the case of a subdivision, combination
or reclassification.

            (b) In case the Company shall issue rights, options or warrants
(other than pursuant to a stockholders' rights plan) to all holders of Common
Stock, entitling them to subscribe for or purchase shares of Common Stock (or
securities convertible into or exchangeable or exercisable for Common Stock), at
a price per share (or having a conversion, exchange or exercise price per share)
less than the Current Market Price (as determined pursuant to Section 10.4(g))
of Common Stock on the record date for the holders of Common Stock entitled to
receive such rights or warrants, the Conversion Rate shall be increased by
multiplying the Conversion Rate in effect immediately prior to such record date
by a fraction of which (1) the numerator shall be the sum of (i) the number of
shares of Common Stock outstanding at the close of business on such record date
and (ii) the aggregate number of shares (the "Underlying Shares") of Common
Stock underlying all such issued rights or warrants (whether by exercise,
conversion, exchange or otherwise), and (2) the denominator shall be the sum of
(i) number of shares of Common Stock outstanding at the close of business on
such record date and (ii) the number of shares of Common Stock which the
aggregate exercise, conversion, exchange or other price at which the Underlying
Shares may be subscribed for or purchased pursuant to such rights, options or
warrants would purchase at such Current Market Price (as defined in pursuant to
Section 10.4(g)). Such increase shall become effective immediately prior to the
opening of business on the day following such record date. In no event shall the
Conversion Rate be decreased pursuant to this Section 10.4(b); provided,
however, that in the event that such rights, options or warrants are only
exercisable upon the occurrence of specified triggering events, then the
Conversion Rate shall not be adjusted until such triggering events occur.

                                      -59-
<PAGE>

            (c) In case the Company shall dividend or distribute to all holders
of Common Stock shares of Capital Stock of the Company (other than Common
Stock), evidences of indebtedness or other assets (other than dividends or
distributions requiring an adjustment to the Conversion Rate in accordance with
Section 10.4(d) or Section 10.4(e), or shall dividend or distribute to all
holders of Common Stock rights, options or warrants to subscribe for or purchase
securities (other than those referred to in Section 10.4(b) or other than
pursuant to a stockholders' rights plan), then in each such case the Conversion
Rate shall be increased by multiplying the Conversion Rate in effect immediately
prior to the close of business on the record date for the determination of
shareholders entitled to such dividend or distribution by a fraction of which
(1) the numerator shall be the Current Market Price of Common Stock on such
record date and (2) the denominator shall be an amount equal to (i) such Current
Market Price less (ii) the fair market value (as determined in good faith by the
Board of Directors, whose determination shall be conclusive and described in a
Board Resolution), on such record date, of the portion of the shares of Capital
Stock, evidences of indebtedness, assets, rights and warrants to be dividend or
distributed applicable to one share of Common Stock, such increase to become
effective immediately prior to the opening of business on the day following such
record date; provided, however, that if such denominator is equal to or less
than zero, then, in lieu of the foregoing adjustment to the Conversion Rate,
adequate provision shall be made so that each Holder shall have the right to
receive upon conversion of its Securities, in addition to the shares of Common
Stock issuable (and cash, if any, payable) upon such conversion, an amount of
shares of Capital Stock, evidences of indebtedness, assets, rights and/or
warrants that such Holder would have received had such Holder converted all of
its Securities on such record date. Notwithstanding the foregoing, in the event
that the Company shall distribute rights, options or warrants (other than those
referred to in Section 10.4(b)) (collectively, "Rights") pro rata to all holders
of Common Stock, the Company may, in lieu of making any adjustment pursuant to
this Section 10.4(c), make proper provision so that each Holder of a Security
who converts such Security (or any portion thereof) on or after the record date
for such distribution and prior to the expiration or redemption of the Rights
shall be entitled to receive upon such conversion, in addition to the shares of
Common Stock issuable (and cash, if any, payable) upon such conversion (the
"Conversion Shares"), a number of Rights to be determined as follows: (A) if
such conversion occurs on or prior to the date for the distribution to the
holders of Rights of separate certificates evidencing such Rights (the
"Distribution Date"), the same number of Rights to which a holder of a number of
shares of Common Stock equal to the number of Conversion Shares would be
entitled at the time of such conversion in accordance with the terms and
provisions of and applicable to the Rights; and (B) if such conversion occurs
after the Distribution Date, the same number of Rights to which a holder of the
number of shares of Common Stock into which the principal amount of the Security
so converted was convertible immediately prior to the Distribution Date would
have been entitled on the Distribution Date in accordance with the terms and
provisions of and applicable to the Rights. Any distribution of rights or
warrants pursuant to a stockholders' rights plan complying with the requirements
set forth in the preceding sentence of this paragraph and with Section 10.13
shall not constitute a distribution of rights or warrants pursuant to this
Section 10.4(c). In no event shall the Conversion Rate be decreased pursuant to
this Section 10.4(c).

            (d) In case the Company shall, by dividend or otherwise, at any time
make a distribution of cash (excluding any cash that is distributed as part of a
distribution requiring a Conversion Rate adjustment pursuant to Section 10.4(e)
to all holders of Common Stock, the

                                      -60-
<PAGE>

Conversion Rate shall be increased by multiplying the Conversion Rate in effect
immediately prior to the close of business on the record date for the
determination of holders of Common Stock entitled to such distribution by a
fraction (1) whose numerator shall be the Current Market Price per share of
Common Stock on such record date and (2) whose denominator shall be an amount
equal to (i) such Current Market Price per share of Common Stock less (ii) the
amount of the distribution per share of Common Stock; provided, however, that
the Conversion Rate shall not be adjusted pursuant to this Section 10.4(d) to
the extent, and only to the extent, such adjustment would cause the Conversion
Price to be less than one cent ($0.01); provided further that, if the
denominator of such fraction shall be equal to or less than zero, the Conversion
Rate shall be instead adjusted so that the Conversion Price is equal to one cent
($0.01). An adjustment to the Conversion Rate pursuant to this Section 10.4(d)
shall become effective immediately prior to the opening of business on the day
immediately following such record date. In no event shall the Conversion Rate be
decreased pursuant to this Section 10.4(d).

            (e) In case a tender offer made by the Company or any Subsidiary for
all or any portion of the Common Stock shall expire and such tender offer (as
amended upon the expiration thereof) shall require the payment to stockholders
(based on the acceptance (up to any maximum specified in the terms of the tender
offer) of Purchased Shares (as defined below)) of an aggregate consideration
having a fair market value (as determined by the Board of Directors, whose
determination shall be conclusive and described in a Board Resolution) that
combined together with (i) the aggregate of the cash plus the fair market value
(as determined by the Board of Directors, whose determination shall be
conclusive and described in a Board Resolution), as of the expiration of such
tender offer, of any non-cash consideration payable in respect of any other
tender offer by the Company or any Subsidiary for all or any portion of the
Common Stock expiring within the 365-day period preceding the expiration of such
tender offer and in respect of which no adjustment pursuant to this Section
10.4(e) or Section 10.4(d) has been made and (ii) the aggregate amount of any
cash distributions to all holders of the Common Stock within 365-day period
preceding the expiration of such tender offer and in respect of which no
adjustment pursuant to Section 10.4(d) has been made (the "combined tender and
cash amount") exceeds 5% of the product of (x) the Current Market Price per
share of the Common Stock as of the last time (the "Expiration Time") tenders
could have been made pursuant to such tender offer (as it may be amended) times
(y) the number of shares of Common Stock outstanding (including any tendered
shares) as of the Expiration Time, then, and in each such case immediately prior
to the opening of business on the day after the date of the Expiration Time, the
Conversion Rate shall be adjusted so that the same shall equal the rate
determined by dividing the Conversion Rate immediately prior to the close of
business on the date of the Expiration Time by a fraction (i) the numerator of
which shall be equal to (A) the product of (I) the Current Market Price per
share of the Common Stock on the date of the Expiration Time multiplied by (II)
the number of shares of Common Stock outstanding (including any tendered shares)
on the Expiration Time less (B) the combined tender and cash amount, and (ii)
the denominator of which shall be equal to the product of (A) the Current Market
Price per share of the Common Stock on the date of the Expiration Time
multiplied by (B) the number of shares of Common Stock outstanding (including
any tendered shares) as of the Expiration Time less the number of all shares
validly tendered and not withdrawn as of the Expiration Time (the shares deemed
so accepted up to any such maximum, being referred to as the "Purchased
Shares").

                                      -61-
<PAGE>

An increase, if any, to the Conversion Rate pursuant to this Section 10.4(e)
shall become effective immediately prior to the opening of business on the
Business Day following the Expiration Date. In the event that the Company or a
Subsidiary is obligated to purchase shares of Common Stock pursuant to any such
tender offer or exchange offer, but the Company or such Subsidiary is
permanently prevented by applicable law from effecting any such purchases, or
all such purchases are rescinded, then the Conversion Rate shall again be
adjusted to be the Conversion Rate which would then be in effect if such tender
offer or exchange offer had not been made. If the application of this Section
10.4(e) to any tender offer or exchange offer would result in a decrease in the
Conversion Rate, no adjustment shall be made for such tender offer or exchange
offer under this Section 10.4(e).

            (f) In addition to the foregoing adjustments in subsections (a),
(b), (c), (d and (e) above, the Company, from time to time and to the extent
permitted by law and subject to any continued listing requirements applicable to
the Common Stock, may increase the Conversion Rate by any amount for a period of
at least twenty (20) days or such longer period as may be required by law or the
continued listing requirements applicable to the Common Stock, if the Board of
Directors has made a determination, which determination shall be conclusive,
that such increase would be in the best interests of the Company; provided,
however, that the Company may not voluntarily reduce the Conversion Price if
such reduction shall result in the issuance, upon exchange of all Securities, of
a number of shares of Common Stock in excess of the thresholds requiring
stockholder approval under the rules of The Nasdaq National Market or such other
U.S. national securities exchange on which the Common stock is traded, unless
the Company has, prior to such reduction in the Conversion Price, obtained any
such stockholder approval. In addition, the Company may also increase the
Conversion Rate as it determines to be advisable in the good faith judgment of
the Board of Directors in order to avoid taxes to recipients on certain
distributions. Such Conversion Rate increase shall be irrevocable during such
period. The Company shall give written notice to the Trustee and cause notice of
such increase to be mailed to each Holder of Securities at such Holder's address
as the same appears on the registry books of the Registrar, at least fifteen
(15) days prior to the date on which such increase commences.

            (g) For the purpose of any computation under subsections (a), (b),
(c) or (d) above of this Section 10.4, the Current Market Price per share of
Common Stock (the "Current Market Price") on the date fixed for determination of
the shareholders entitled to receive the issuance or distribution requiring such
computation (the "Determination Date") shall be deemed to be the average of the
Closing Sale Prices for the ten (10) consecutive Trading Days immediately
preceding the Determination Date, and, for the purpose of any computation under
Section 10.4(e) above, the Current Market Price per share of Common Stock on the
Expiration Date for Tender Officer requiring such computation shall be deemed to
be the average of the Closing Sale Price for the ten (10) consecutive Trading
Days immediately preceding the Expiration Date, as the case may be; provided,
however, that (1) if the "ex" date for any event (other than the event requiring
such computation) that requires an adjustment to the Conversion Rate pursuant to
subsections (a), (b), (c), (d) and (e) above occurs on or after the tenth (10th)
Trading Day prior to the Determination Date or Expiration Date, whichever is
applicable, and prior to the "ex" date for the issuance or distribution
requiring such computation, the Closing Sale Price for each Trading Day prior to
the "ex" date for such other event shall be adjusted by multiplying such Closing
Sale Price by the reciprocal of the fraction by which the Conversion

                                      -62-
<PAGE>

Rate is so required to be adjusted as a result of such other event, (2) if the
"ex" date for any event (other than the event requiring such computation) that
requires an adjustment to the Conversion Rate pursuant to subsections (a), (b),
(c), (d) and (e) above occurs on or after the "ex" date for the issuance or
distribution requiring such computation and on or prior to the Determination
Date or the Expiration Date, whichever is applicable, the Closing Sale Price for
each Trading Day on and after the "ex" date for such other event shall be
adjusted by multiplying such Closing Sale Price by the same fraction by which
the Conversion Rate is so required to be adjusted as a result of such other
event, and (3) if the "ex" date for the event requiring such computation is on
or prior to the Determination Date or Expiration Date, whichever is applicable,
after taking into account any adjustment required pursuant to clause (1) or (2)
of this proviso, the Closing Sale Price for each Trading Day on and after such
"ex" date shall be adjusted by adding thereto the amount of any cash and the
fair market value (as determined in good faith by the Board of Directors in a
manner consistent with any determination of such value for the purposes of this
Section 10.4, whose determination shall be conclusive and described in a
Resolution of the Board of Directors) of the evidences of indebtedness, shares
of Capital Stock or other securities or assets or cash being distributed (in the
event requiring such computation) applicable to one share of Common Stock as of
the close of business on the day before such "ex" date.

      For purposes of this subsection, the term "ex" date, (i) when used with
respect to any issuance or distribution, means the first date on which the
Common Stock trades the regular way on the relevant exchange or in the relevant
market from which the Closing Sale Price was obtained without the right to
receive such issuance or distribution, (ii) when used with respect to any
subdivision or combination of shares of Common Stock, means the first date on
which the Common Stock trades the regular way on such exchange or in such market
after the time at which such subdivision or combination becomes effective, and
(iii) when used with respect to any Tender Offer means the first date on which
the Common Stock trades the regular way on such exchange or in such market after
the expiration time of such Tender Offer (as it may be amended or extended).

SECTION 10.5 Notice of Adjustments of Conversion Rate.

      Whenever the Conversion Rate is adjusted as herein provided:

      (a) the Company shall compute the adjusted Conversion Rate in accordance
with Section 10.4 and shall prepare a certificate signed by the Chief Financial
Officer of the Company setting forth the adjusted Conversion Rate and showing in
reasonable detail the facts upon which such adjustment is based, and such
certificate shall promptly be filed with the Trustee and with the Conversion
Agent; and

      (b) upon each such adjustment, a notice stating that the Conversion Rate
has been adjusted and setting forth the adjusted Conversion Rate shall be
required, and as soon as practicable after it is required, such notice shall be
provided by the Company to all Holders in accordance with Section 1.6.

Neither the Trustee nor the Conversion Agent shall be under any duty or
responsibility with respect to any such certificate or the information and
calculations contained therein, except to exhibit the same to any Holder of
Securities desiring inspection thereof at its office during

                                      -63-
<PAGE>

normal business hours. Unless and until a Responsible Officer of the Trustee and
Conversion Agent receive notice of an adjusted Conversion Rate, the Trustee and
the Conversion Agent may rely without inquiry on the Conversion Rate most
recently in effect.

SECTION 10.6 Notice of Certain Corporate Action.

      In case:

      (a) the Company shall declare a dividend (or any other distribution) on
Common Stock payable (i) otherwise than exclusively in cash or (ii) exclusively
in cash in an amount that would require any adjustment pursuant to Section 10.4;
or

      (b) the Company shall authorize the granting to the holders of Common
Stock of rights, options or warrants to subscribe for or purchase any shares of
Capital Stock of any class or of any other rights; or

      (c) of any reclassification of the Common Stock of the Company, or of any
consolidation, merger or share exchange to which the Company is a party and for
which approval of any stockholders of the Company is required, or of the
conveyance, sale, transfer or lease (other than a grant of security interest) of
all or substantially all of the assets of the Company; or

      (d) of the voluntary or involuntary dissolution, liquidation or winding up
of the Company;

then the Company shall cause to be filed at each office or agency maintained for
the purpose of conversion of Securities pursuant to Section 8.2, and shall cause
to be provided to all Holders in accordance with Section 1.6, at least 20 days
(or 10 days in any case specified in clause (a) or (b) above) prior to the
applicable record or effective date hereinafter specified, a notice stating (1)
the date on which a record is to be taken for the purpose of such dividend,
distribution, rights, options or warrants, or, if a record is not to be taken,
the date as of which the holders of Common Stock of record to be entitled to
such dividend, distribution, rights, options or warrants are to be determined or
(2) the date on which such reclassification, consolidation, merger, conveyance,
transfer, sale, lease, dissolution, liquidation or winding up is expected to
become effective, and the date as of which it is expected that holders of Common
Stock of record shall be entitled to exchange their shares of Common Stock for
securities, cash or other property deliverable upon such reclassification,
consolidation, merger, conveyance, transfer, sale, lease, dissolution,
liquidation or winding up. Neither the failure to give such notice or the notice
referred to in the following paragraph nor any defect therein shall affect the
legality or validity of the proceedings described in clauses (a) through (d) of
this Section 10.6. If at the time the Trustee shall not be the Conversion Agent,
a copy of such notice shall also forthwith be filed by the Company with the
Trustee.

      The Company shall cause to be filed at each office or agency maintained
for the purpose of conversion of Securities pursuant to Section 8.2, and shall
cause to be provided to all Holders in accordance with Section 1.6, notice of
any Tender Offer by the Company or any Subsidiary for all or any portion of the
Common Stock at or about the time that such notice of tender offer is provided
to the public generally.

                                      -64-
<PAGE>

SECTION 10.7 Company to Reserve Common Stock.

      The Company shall at all times reserve and keep available, free from
preemptive rights, out of its authorized but unissued Common Stock, for the
purpose of effecting the conversion of Securities, the full number of shares of
Common Stock then issuable upon the conversion of all Outstanding Securities.

SECTION 10.8 Taxes on Conversions.

      Except as provided in the next sentence, the Company will pay any and all
taxes and duties that may be payable in respect of the issue or delivery of
shares of Common Stock on conversion of Securities pursuant hereto. The Company
shall not, however, be required to pay any tax or duty which may be payable in
respect of (i) income of the Holder or (ii) any transfer involved in the issue
and delivery of shares of Common Stock in a name other than that of the Holder
of the Security or Securities to be converted, and no such issue or delivery
shall be made unless and until the Person requesting such issue has paid to the
Company the amount of any such tax or duty or has established to the
satisfaction of the Company that such tax or duty has been paid.

SECTION 10.9 Covenant as to Common Stock.

      The Company agrees that all shares of Common Stock that may be delivered
upon conversion of Securities, upon such delivery, will have been duly
authorized and validly issued and will be fully paid and nonassessable and,
except as provided in Section 10.8, the Company will pay all taxes, liens and
charges with respect to the issue thereof.

SECTION 10.10 Cancellation of Converted Securities.

      All Securities delivered for conversion shall be delivered to the Trustee
or its agent to be cancelled by or at the direction of the Trustee, which shall
dispose of the same as provided in Section 2.10.

SECTION 10.11 Provision in Case of Consolidation, Merger or Sale of Assets.

      In case of any consolidation or merger of the Company with or into any
other Person, any merger of another Person with or into the Company (other than
a merger that does not result in any reclassification, conversion, exchange or
cancellation of outstanding shares of Common Stock of the Company) or any
conveyance, sale, transfer or lease (other than a grant of security interest) of
all or substantially all of the assets of the Company, the Person formed by such
consolidation or resulting from such merger or that acquires such assets, as the
case may be, shall execute and deliver to the Trustee a supplemental indenture
providing that the Holder of each Security then Outstanding shall have the right
thereafter, during the period such Security shall be convertible as specified in
Section 11.1, to convert such Security only into the kind and amount of
securities, cash and other property receivable upon such consolidation, merger,
conveyance, sale, transfer or lease (other than a grant of security interest) by
a holder of the number of shares of Common Stock of the Company into which such
Security might have been converted immediately prior to such consolidation,
merger, conveyance, sale, transfer or lease (other than a grant of security
interest), assuming such holder of Common Stock of the Company (a) is not a

                                      -65-
<PAGE>

Person with which the Company consolidated or merged with or into or that merged
into or with the Company or to which such conveyance, sale, transfer or lease
(other than a grant of security interest) was made, as the case may be (a
"Constituent Person"), or an Affiliate of a Constituent Person and (b) failed to
exercise his rights of election, if any, as to the kind or amount of securities,
cash and other property receivable upon such consolidation, merger, conveyance,
sale, transfer or lease (other than a grant of security interest) (provided that
if the kind or amount of securities, cash and other property receivable upon
such consolidation, merger, conveyance, sale, transfer, or lease (other than a
grant of security interest) is not the same for each share of Common Stock of
the Company held immediately prior to such consolidation, merger, conveyance,
sale, transfer or lease by others than a Constituent Person or an Affiliate
thereof and in respect of which such rights of election shall not have been
exercised ("Non-electing Share"), then for the purpose of this Section 10.11 the
kind and amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer or lease by the holders of
each Non-electing Share shall be deemed to be the kind and amount so receivable
per share by a plurality of the Non-electing Shares). Such supplemental
indenture shall provide for adjustments that, for events subsequent to the
effective date of such supplemental indenture, shall be as nearly equivalent as
may be practicable to the adjustments provided for in this Article Ten. The
above provisions of this Section 10.11 shall similarly apply to successive
consolidations, mergers, conveyances, sales, transfers or leases (other than a
grant of security interest). Notice of the execution of such a supplemental
indenture shall be given by the Company to the Holder of each Security as
provided in Section 1.6 promptly upon such execution.

      Neither the Trustee nor the Conversion Agent shall be under any
responsibility to determine the correctness of any provisions contained in any
such supplemental indenture relating either to the kind or amount of shares of
stock or other securities or property or cash receivable by Holders of
Securities upon the conversion of their Securities after any such consolidation,
merger, conveyance, transfer, sale or lease or to any such adjustment but may
accept as conclusive evidence of the correctness of any such provisions, and
shall be protected in relying upon, an Officers Certificate or an Opinion of
Counsel with respect thereto, which the Company shall cause to be furnished to
the Trustee upon request.

SECTION 10.12 Responsibility of Trustee for Conversion Provisions.

      The Trustee, subject to the provisions of Section 5.1, and any Conversion
Agent shall not at any time be under any duty or responsibility to any Holder of
Securities to determine whether any facts exist that may require any adjustment
of the Conversion Rate, or with respect to the nature or extent of any such
adjustment when made, or with respect to the method employed, or herein or in
any supplemental indenture provided to be employed, in making the same, or
whether a supplemental indenture need be entered into. Neither the Trustee,
subject to the provisions of Section 5.1, nor any Conversion Agent shall be
accountable with respect to the validity or value (or the kind or amount) of any
Common Stock, or of any other securities or property or cash, that may at any
time be issued or delivered upon the conversion of any Security; and it or they
do not make any representation with respect thereto. Neither the Trustee,
subject to the provisions of Section 5.1, nor any Conversion Agent shall be
responsible for any failure of the Company to make or calculate any cash payment
or to issue, transfer or deliver any shares of Common Stock or share
certificates or other securities or property or cash upon the

                                      -66-
<PAGE>

surrender of any Security for the purpose of conversion; and the Trustee,
subject to the provisions of Section 5.1, and any Conversion Agent shall not be
responsible for any failure of the Company to comply with any of the covenants
of the Company contained in this Article Ten.

SECTION 10.13 Rights Distributions Pursuant to a Stockholders' Rights Plan.

      In the event that the Company implements a stockholders' rights plan after
the date hereof, the Company shall provide that the Holders will receive upon
conversion of their Securities, in addition to shares of Common Stock issuable
(and cash, if any, payable) upon such conversion, the rights described therein
(whether or not the rights have been separated from the Common Stock prior to
the time of conversion).

SECTION 10.14 No Adjustment.

      No adjustment in the Conversion Rate shall be required until cumulative
adjustments amount to one percent (1%) or more of the Conversion Price as last
adjusted (or, if never adjusted, the initial Conversion Rate); provided,
however, that any adjustments which by reason of this Section 10.14 are not
required to be made shall be carried forward and taken into account in any
subsequent adjustment. All calculations under this Article Ten shall be made to
the nearest cent or to the nearest one-hundredth of a share, as the case may be.

      If any dividend or distribution is declared and the Conversion Rate is
adjusted pursuant to Section 10.4 on account of such dividend or distribution,
but such dividend or distribution is thereafter not paid or made, the Conversion
Rate shall again be adjusted to the Conversion Rate which would then be in
effect had such dividend or distribution not been declared.

      No adjustment to the Conversion Rate need be made for a transaction
referred to in this Article Ten if Holders are to participate in the transaction
without conversion on a basis and with notice that the Board of Directors
determines in good faith to be fair and appropriate in light of the basis and
notice on which holders of Common Stock participate in the transaction (which
determination shall be described in a Board Resolution). A distribution of
separate certificates representing any rights under a stockholders' rights plan
or the exercise of any such rights in accordance with any such stockholder
rights plan, will not trigger a conversion rate adjustment.

      Notwithstanding the foregoing provisions of this Article Ten, no
adjustment of the Conversion Rate shall be required to be made (a) upon the
issuance of shares of Common Stock pursuant to any present or future plan for
the reinvestment of dividends or (b) upon a change in the par value of the
Common Stock.

SECTION 10.15 Rights Issued in Respect of Common Stock.

      Rights, options or warrants distributed by the Company to all holders of
Common Stock entitling the holders thereof to subscribe for or purchase shares
of the Company's capital stock (either initially or under certain
circumstances), which rights, options or warrants, until the occurrence of a
specified event or events ("Trigger Event"):

                  (a) are deemed to be transferred with such shares of Common
Stock,

                                      -67-
<PAGE>

                  (b) are not exercisable, and

                  (c) are also issued in respect of future issuances of Common
Stock

shall not be deemed distributed for purposes of Section 10.4(b) until the
occurrence of the earliest Trigger Event. In addition, in the event of any
distribution of rights, options or warrants, or any Trigger Event with respect
thereto, that shall have resulted in an adjustment to the Conversion Rate under
Section 10.4(b), (1) in the case of any such rights, options or warrants that
shall all have been redeemed or repurchased without exercise by any holders
thereof, the Conversion Rate shall be readjusted upon such final redemption or
repurchase to give effect to such distribution or Trigger Event, as the case may
be, as though it were a cash distribution, equal to the per share redemption or
repurchase price received by a holder of Common Stock with respect to such
rights, options or warrants (assuming such holder had retained such rights,
options or warrants), made to all holders of Common Stock as of the date of such
redemption or repurchase, and (2) in the case of any such rights, options or
warrants all of which shall have expired without exercise by any holder thereof,
the Conversion Price shall be readjusted as if such issuance had not occurred.

                                 ARTICLE ELEVEN

                           SUBORDINATION OF SECURITIES

SECTION 11.1 Securities Subordinate to Senior Debt.

      The Company covenants and agrees, and each Holder of a Security by his
acceptance thereof likewise covenants and agrees, that to the extent and in the
manner hereinafter set forth in this Article Eleven (subject to the provisions
of Article Three) the indebtedness represented by the Securities and the payment
of the principal of (and premium, if any) and interest (including Liquidated
Damages, if any) on, and any payment of the Change in Control Purchase Price (if
applicable) with respect to, each and all of the Securities are hereby expressly
made subordinate and subject in right of payment to the prior payment in full in
cash or Cash Equivalents of all Senior Debt.

SECTION 11.2 No Payments in Certain Circumstances; Payment Over of Proceeds Upon
             Dissolution, Etc.

      No payment on account of principal of, premium, if any, or interest (and
Liquidated Damages, if any) on, or redemption or repurchase of, the Securities
shall be made if, at the time of such payment: (a) a default in the payment of
principal, premium, if any, or interest or other amounts due on or in connection
with any Senior Debt, including any default under any redemption or repurchase
obligation, occurs and is continuing (or, in the case of Senior Debt for which
there is a period of grace, in the event of such a default that continues beyond
the period of grace, if any, specified in the instrument or lease evidencing
such Senior Debt), unless and until such default shall have been cured or waived
or shall have ceased to exist; or (b) a default, other than a payment default,
on Designated Senior Debt occurs and is continuing that then permits holders of
such Designated Senior Debt to accelerate its maturity and the Trustee receives
a notice of the default (a "Payment Blockage Notice") from the Company, a holder
of

                                      -68-
<PAGE>

Designated Senior Debt or a Representative. Notwithstanding the foregoing, the
Company may make, and the Trustee may receive and shall apply, any payment in
respect of the Securities (for principal, premium, if any, or interest (and
Liquidated Damages, if any) or repurchase) if such payment was made prior to the
occurrence of any of the contingencies specified in clauses (a) and (b) above.

      If the Trustee receives any Payment Blockage Notice pursuant to clause (b)
above, no subsequent Payment Blockage Notice shall be effective for purposes of
this Section 11.2 unless and until (1) at least 365 days shall have elapsed
since the effectiveness of the immediately prior Payment Blockage Notice and (2)
all scheduled payments of principal, premium, if any, and interest (including
Liquidated Damages, if any) on the Securities that have come due have been paid
in full in cash. No nonpayment default that existed or was continuing on the
date of delivery of any Payment Blockage Notice to the Trustee shall be, or be
made, the basis for a subsequent Payment Blockage Notice unless such existing
nonpayment default has been cured for a period of at least 90 days.

      The Company may and shall resume payments on and distributions in respect
of the Securities (including missed payments, if any) upon the earlier of: (A)
the date upon which the default is cured or waived, and (B) in the case of a
default referred to in clause (b) of the second preceding paragraph, 179 days
after the Payment Blockage Notice is received if the maturity of such Designated
Senior Debt has not been accelerated such that such Designated Senior Debt is
then presently payable, unless this Indenture otherwise prohibits the payment or
distribution at the time of such payment or distribution.

      Upon (i) any acceleration of the principal amount due on the Securities as
a result of an Event of Default or (ii) any payment or distribution of assets of
the Company of any kind or character, whether in cash, property or securities,
to creditors upon any dissolution, winding up or total or partial liquidation or
reorganization of the Company, whether voluntary or involuntary, or in
bankruptcy, insolvency, receivership or other proceedings, all principal of,
premium, if any, sinking fund and interest or other amounts due, or to become
due, upon or in connection with all Senior Debt shall first be paid in full in
cash or Cash Equivalents, or payment thereof provided for in cash or Cash
Equivalents in accordance with its terms, before any payment is made on account
of the principal of, premium, if any, or interest (and Liquidated Damages, if
any) on, or repurchase of, the indebtedness evidenced by the Securities, and
upon any such dissolution or winding up or liquidation or reorganization any
payment or distribution of assets of the Company of any kind or character,
whether in cash, property or securities, to which the Holders of the Securities
or the Trustee under this Indenture would be entitled, except for the provisions
hereof, shall be paid by the Company or by any receiver, trustee in bankruptcy,
liquidating trustee, agent or other Person making such payment or distribution,
or by the Holders of the Securities or by the Trustee under this Indenture if
received by them or it, as the case may be, directly to the holders of Senior
Debt (pro rata to each such holder on the basis of the respective amounts of
Senior Debt held by such holder) or their representatives, to the extent
necessary to pay all Senior Debt in full, in cash or Cash Equivalents, after
giving effect to any concurrent payment or distribution to or for the holders of
Senior Debt, before any payment or distribution is made to the Holders of the
Securities or to the Trustee under this Indenture.

                                      -69-
<PAGE>

      In the event that, contrary to the foregoing, any payment or distribution
of assets of the Company of any kind or character, whether in cash, property or
securities (other than junior securities, as defined in Section 11.11), shall be
received by the Trustee or the Holders of the Securities before all Senior Debt
is paid in full in cash or Cash Equivalents or provision made for such payment
in accordance with its terms, such payment or distribution shall be paid over or
delivered to the holders of such Senior Debt or their representative or
representatives, or to the trustee or trustees under any indenture pursuant to
which any instruments evidencing any of such Senior Debt have been issued, as
their respective interests may appear, for application to the payment of all
Senior Debt remaining unpaid to the extent necessary to pay all such Senior Debt
in full in cash or Cash Equivalents in accordance with its terms, after giving
effect to any concurrent payment or distribution to or for the holders of such
Senior Debt.

      Subject to the payment in full in cash or Cash Equivalents of all Senior
Debt, the Holders of the Securities (together with the holders of any other
indebtedness of the Company that is subordinated in right of payment to the
payment in full of all Senior Debt that is not subordinated in right of payment
to the Securities and that by its terms grants such right of subrogation to the
holders thereof) shall be subrogated to the rights of the holders of Senior Debt
to receive payments or distributions of assets of the Company made on the Senior
Debt until the principal of, premium, if any, and interest on, or amounts
payable upon repurchase of, the Securities shall be paid in full, and, for the
purposes of such subrogation, no payments or distributions to the holders of
Senior Debt of any cash, property or securities to which the Holders of the
Securities or the Trustee would be entitled except for the provisions of this
Article Eleven, and no payment over pursuant to the provisions of this Article
Eleven to the holders of Senior Debt by the Holders of the Securities or the
Trustee, shall, as between the Company, its creditors other than the holders of
Senior Debt, and the Holders of Securities, be deemed to be a payment by the
Company to the holders of or on account of Senior Debt, it being understood that
the provisions of this Article Eleven are and are intended solely for the
purpose of defining the relative rights of the Holders of the Securities, on the
one hand, and the holders of Senior Debt, on the other hand.

SECTION 11.3 Trustee to Effectuate Subordination.

      Each Holder of a Security by his acceptance thereof authorizes and directs
the Trustee on his behalf to take such action as may be necessary or appropriate
to effectuate the subordination provided in this Article Eleven and appoints the
Trustee his attorney-in-fact for any and all such purposes.

SECTION 11.4 No Waiver of Subordination Provisions.

      No right of any present or future holder of any Senior Debt to enforce
subordination as herein provided shall at any time in any way be prejudiced or
impaired by any act or failure to act on the part of the Company or by any act
or failure to act, in good faith, by any such holder of any Senior Debt or by
any non-compliance by the Company with the terms, provisions and covenants of
this Indenture, regardless of any knowledge thereof any such holder may have or
be otherwise charged with.

      Without in any way limiting the generality of the foregoing paragraph, the
holders of Senior Debt may, at any time and from time to time, without the
consent of or notice to the

                                      -70-
<PAGE>

Trustee or the Holders of the Securities, without incurring responsibility to
the Holders of the Securities and without impairing or releasing the
subordination provided in this Article Eleven or the obligations hereunder of
the Holders of the Securities to the holders of Senior Debt, do any one or more
of the following in good faith: (a) change the manner, place or terms of payment
or extend the time of payment of, or renew or alter, Senior Debt or otherwise
amend or supplement in any manner Senior Debt or any instrument evidencing the
same or any agreement under which Senior Debt is outstanding; (b) sell,
exchange, release or otherwise deal with any property pledged, mortgaged or
otherwise securing Senior Debt; (c) release any Person liable in any manner for
the collection of Senior Debt; and (d) exercise or refrain from exercising any
rights against the Company and any other Person.

SECTION 11.5 Notice to Trustee.

      The Company shall give prompt written notice to the Trustee of any fact
known to the Company that would prohibit the making of any payment to or by the
Trustee in respect of the Securities. Notwithstanding the provisions of this
Article Eleven or any other provision of this Indenture, the Trustee shall not
be charged with knowledge of the existence of any facts that would prohibit the
making of any payment to or by the Trustee in respect of the Securities, unless
and until a Responsible Officer of the Trustee shall have received written
notice thereof from the Company or a holder of Senior Debt or from any trustee,
agent or representative therefor; and, prior to the receipt of any such written
notice, the Trustee, subject to the provisions of Section 5.1, shall be entitled
in all respects to assume that no such facts exist; provided, however, that if
the Trustee shall not have received the notice provided for in this Section 11.5
prior to the date upon which by the terms hereof any money may become payable
for any purpose (including, without limitation, the payment of the principal of
(and premium, if any) or interest on any Security), then, anything herein
contained to the contrary notwithstanding, the Trustee shall have full power and
authority to receive such money and to apply the same to the purpose for which
such money was received and shall not be affected by any notice to the contrary
that may be received by it within two Business Days prior to such date.

      Subject to the provisions of Section 5.1, the Trustee shall be entitled to
rely on the delivery to it of a written notice by a Person representing himself
to be a holder of Senior Debt (or a trustee, agent or representative therefor)
to establish that such notice has been given by a holder of Senior Debt (or a
trustee, agent or representative therefor). In the event that the Trustee
determines in good faith that further evidence is required with respect to the
right of any Person as a holder of Senior Debt to participate in any payment or
distribution pursuant to this Article Eleven, the Trustee may request such
Person to furnish evidence to the reasonable satisfaction of the Trustee as to
the amount of Senior Debt held by such Person, the extent to which such Person
is entitled to participate in such payment or distribution and any other facts
pertinent to the rights of such Person under this Article Eleven, and if such
evidence is not furnished, the Trustee may defer any payment to such Person
pending judicial determination as to the right of such Person to receive such
payment.

SECTION 11.6 Reliance on Judicial Order or Certificate of Liquidating Agent.

      Upon any payment or distribution of assets of the Company referred to in
this Article Eleven, the Trustee, subject to the provisions of Section 5.1, and
the Holders of the Securities

                                      -71-
<PAGE>

shall be entitled to rely upon any order or decree entered by any court of
competent jurisdiction in which such insolvency, bankruptcy, receivership,
liquidation, reorganization, dissolution, winding up or similar case or
proceeding is pending, or a certificate of the trustee in bankruptcy, receiver,
liquidating trustee, custodian, assignee for the benefit of creditors, agent or
other Person making such payment or distribution, delivered to the Trustee or to
the Holders of Securities, for the purpose of ascertaining the Persons entitled
to participate in such payment or distribution, the holders of the Senior Debt
and other indebtedness of the Company, the amount thereof or payable thereon,
the amount or amounts paid or distributed thereon and all other facts pertinent
thereto or to this Article Eleven.

SECTION 11.7 Trustee Not Fiduciary for Holders of Senior Debt.

      The Trustee shall not be deemed to owe any fiduciary duty to the holders
of Senior Debt and shall not be liable to any such holders if it shall in good
faith mistakenly pay over or distribute to Holders of Securities or to the
Company or to any other Person cash, property or securities to which any holders
of Senior Debt shall be entitled by virtue of this Article Eleven or otherwise.
With respect to the holders of Senior Debt, the Trustee undertakes to perform or
to observe only such of its covenants or obligations as are specifically set
forth in this Article Eleven, and no implied covenants or obligations with
respect to holders of Senior Debt shall be read into this Indenture against the
Trustee.

SECTION 11.8 Reliance by Holders of Senior Debt on Subordination Provisions.

      Each Holder by accepting a Security acknowledges and agrees that the
foregoing subordination provisions are, and are intended to be, an inducement
and a consideration to each holder of any Senior Debt, whether such Senior Debt
was created or acquired before or after the issuance of the Securities, to
acquire and continue to hold, or to continue to hold, such Senior Debt, and such
holder of Senior Debt shall be deemed conclusively to have relied on such
subordination provisions in acquiring and continuing to hold, or in continuing
to hold, such Senior Debt. Such holders of the Company's Senior Debt are
intended by the parties to the Indenture to be third-party creditor
beneficiaries under this Indenture for the purposes of enforcing the provisions
of this Article Eleven.

SECTION 11.9 Rights of Trustee as Holder of Senior Debt; Preservation of
             Trustee's Rights.

      The Trustee in its individual capacity shall be entitled to all the rights
set forth in this Article Eleven with respect to any Senior Debt that may at any
time be held by it, to the same extent as any other holder of Senior Debt, and
nothing in this Indenture shall deprive the Trustee of any of its rights as such
holder.

      Nothing in this Article Eleven shall apply to claims of, or payments to,
the Trustee under or pursuant to Section 5.7.

SECTION 11.10 Article Applicable to Paying Agents.

      In case at any time any Paying Agent other than the Trustee shall have
been appointed by the Company and be then acting hereunder, the term "Trustee"
as used in this Article Eleven

                                      -72-
<PAGE>

shall in such case (unless the context otherwise requires) be construed as
extending to and including such Paying Agent within its meaning as fully for all
intents and purposes as if such Paying Agent were named in this Article Eleven
in addition to or in place of the Trustee; provided, however, that Section 11.9
shall not apply to the Company or any Affiliate of the Company if the Company or
any such Affiliate acts as Paying Agent.

SECTION 11.11 Certain Conversions and Repurchases Deemed Payment.

      For the purposes of this Article Eleven only (a) the issuance and delivery
of junior securities upon conversion of Securities in accordance with Article
Ten or upon the repurchase of Securities in accordance with Article Twelve shall
not be deemed to constitute a payment or distribution on account of the
principal of or premium or interest or Liquidated Damages on Securities or on
account of the purchase or other acquisition of Securities, and (b) the payment,
issuance or delivery of cash, property or securities (other than junior
securities) upon conversion of a Security shall be deemed to constitute payment
on account of the principal of such Security. For the purposes of this Section
11.11, the term "junior securities" means (1) shares of any stock of any class
of the Company and any cash, property or securities into which the Securities
are convertible pursuant to Article Ten and (2) securities of the Company that
are subordinated in right of payment to all Senior Debt that may be outstanding
at the time of issuance or delivery of such securities to substantially the same
extent as, or to a greater extent than, the Securities are so subordinated as
provided in this Article Eleven. Nothing contained in this Article Eleven or
elsewhere in this Indenture or in the Securities is intended to or shall impair,
as among the Company, its creditors and the Holders of the Securities, the
right, which is absolute and unconditional, of the Holder of any Security to
convert such Security in accordance with Article Ten or to exchange such
Security for Common Stock or successor Common Stock in accordance with Article
Twelve if the Company elects to satisfy the obligations under Article Twelve by
the delivery of Common Stock or Successor Common Stock.

                                 ARTICLE TWELVE

                       REPURCHASE UPON A CHANGE IN CONTROL

SECTION 12.1 Purchase of Securities at Option of the Holder Upon Change in
             Control.

      (a) If there shall have occurred a Change in Control, all or any portion
of the Securities of any Holder equal to $1,000 or a whole multiple of $1,000,
shall be repurchased by the Company, at the option of such Holder, at a
repurchase price equal to 100% of the aggregate principal amount of the
Securities to be repurchased, together with accrued and unpaid interest
(including Liquidated Damages, if any) to, but excluding, the purchase date (the
"Change in Control Purchase Price"), on the date (the "Change in Control
Purchase Date") that is 45 days after the date the Company delivers the Company
Notice (or if such 45th day is not a Business Day, the next succeeding Business
Day); provided, however, that if the Change in Control Purchase Date is after a
Regular Record Date but on or prior to the corresponding Interest Payment Date,
the accrued and unpaid interest becoming due on such Interest Payment

                                      -73-
<PAGE>

Date shall be payable to the Holders of such Securities, or one or more
predecessor Securities, registered as such on the relevant Regular Record Date
according to their terms.

      If there shall have occurred on or prior to the Stated Maturity of the
Securities a Change in Control described in clause (2) of the definition of a
Change in Control, the Company will pay on the Change in Control Purchase Date a
Make-Whole Premium to the Holders of the Securities in addition to the Change in
Control Purchase Price. The Make-Whole Premium will also be paid on the Change
in Control Purchase Date to the Holders of the Securities who convert their
Securities on or after the date on which the Company has given the Company
Notice to all Holders of Securities in accordance with this Section 12.1 and on
or before the Change in Control Purchase Date.

      The "Make-Whole Premium" will be determined by reference to the table
below and is based on the date on which the Change in Control described in
clause (2) of the definition of a Change in Control becomes effective (the
"Effective Date") and the price (the "Stock Price") paid per share of the Common
Stock in the transaction constituting the Change in Control described in clause
(2) of the definition of a Change in Control. If the holders of the Common Stock
receive only cash in the transaction, the Stock Price shall be the cash amount
paid per share of the Common Stock. Otherwise, the Stock Price shall be equal to
the average Closing Sale Price of the Common Stock over the five Trading Day
period ending on the Trading Day immediately preceding the Effective Date.

      The following table shows what the Make-Whole Premium would be for each
hypothetical Stock Price and Effective Date set forth below, expressed as a
percentage of the principal amount of the Securities. No Make-Whole Premium
shall be payable if the Effective Date is later than April 1, 2010.

       Make-Whole Premium Upon a Change in Control (% of Principal Amount)

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------
                                        Stock Price on Effective Date
                   ------------------------------------------------------------------------
Effective Date     $12.30     $13.00     $14.00     $15.00     $16.00     $17.00     $18.00
-------------------------------------------------------------------------------------------
<S>                <C>        <C>        <C>        <C>        <C>        <C>        <C>
4/5/05              0.00%     13.11%     18.74%     22.90%     22.05%     21.29%     20.64%

4/1/06              0.00%     11.02%     16.47%     20.49%     19.54%     18.71%     17.99%

4/1/07              0.00%      8.97%     14.15%     17.95%     16.84%     15.89%     15.10%

4/1/08              0.00%      6.52%     11.27%     14.77%     13.43%     12.34%     11.46%

4/1/09              0.00%      3.54%      7.55%     10.54%      8.88%      7.62%      6.68%

4/1/10              0.00%      0.00%      0.00%      0.00%      0.00%      0.00%      0.00%

<CAPTION>
-------------------------------------------------------------------------------------------
                                        Stock Price on Effective Date
                   ------------------------------------------------------------------------
Effective Date     $19.00     $20.00     $25.00     $30.00     $40.00     $50.00     $60.00
-------------------------------------------------------------------------------------------
<S>                <C>        <C>        <C>        <C>        <C>        <C>        <C>
4/5/05             20.04%     19.52%     17.51%     16.14%     14.10%     12.42%     10.91%

4/1/06             17.36%     16.82%     14.86%     13.62%     11.92%     10.54%      9.29%

4/1/07             14.42%     13.86%     11.95%     10.90%      9.59%      8.56%      7.60%

4/1/08             10.73%     10.14%      8.40%      7.60%      6.73%      6.06%      5.42%

4/1/09              5.98%      5.46%      4.25%      3.86%      3.47%      3.16%      2.86%

4/1/10              0.00%      0.00%      0.00%      0.00%      0.00%      0.00%      0.00%
</TABLE>

      The actual Stock Price and Effective Date may not be set forth on the
table, in which case:

            (1) if the actual Stock Price on the Effective Date is between two
      Stock Prices on the table or the actual Effective Date is between two
      Effective Dates on the table, the Make-Whole Premium will be determined by
      a straight-line interpolation between the

                                      -74-
<PAGE>

      Make-Whole Premiums set forth for the two Stock Prices and the two
      Effective Dates on the table based on a 365-day year, as applicable;

            (2) if the Stock Price on the Effective Date exceeds $60.00 per
      share (subject to adjustment described below), no Make-Whole Premium will
      be paid; and

            (3) if the Stock Price on the Effective Date is less than $12.30 per
      share (subject to adjustment described below), no Make-Whole Premium will
      be paid.

      The Stock Prices set forth in the first column of the table above will be
adjusted as of any date on which the Conversion Rate is adjusted. The adjusted
Stock Prices will equal the Stock Prices applicable immediately prior to such
adjustment multiplied by a fraction, the numerator of which is the Conversion
Rate immediately prior to the adjustment giving rise to the Stock Price
adjustment and the denominator of which is the Conversion Rate so adjusted.

      The Company shall pay, at its option, the Change in Control Purchase Price
and/or Make-Whole Premium in cash or shares of Common Stock or Successor Common
Stock or, in the case of the Make-Whole Premium, the same form of consideration
used to pay for the shares of the Common Stock in connection with the
transaction constituting the Change in Control.

      If the Company pays the Change in Control Purchase Price in shares of
Common Stock or Successor Common Stock, the value of the Common Stock or the
Successor Common Stock to be delivered in respect of the Change in Control
Purchase Price shall be deemed to be equal to 95% of the average of the Closing
Sale Prices per share for the five consecutive Trading Days ending on and
including the third day prior to the Change in Control Purchase Date; provided
that the Change in Control Purchase Price may only be paid in Successor Common
Stock if such common stock is traded on The Nasdaq National Market or other U.S.
national securities exchange.

      If the Company pays the Make-Whole Premium in shares of Common Stock or
Successor Common Stock, the value of the Common Stock or the Successor Common
Stock to be delivered in respect of the Make-Whole Premium shall be deemed equal
to 95% of the average of the Closing Sale Prices per share for the ten Trading
Day period ending on the Trading Day immediately preceding the Change in Control
Purchase Date. The Company may pay the Make-Whole Premium in shares of Common
Stock or the Successor Common Stock only if the information necessary to
calculate the Closing Sale Price per share is published in a daily newspaper of
general circulation or by other appropriate means.

      If the Company pays the Make-Whole Premium in the same form of
consideration used to pay for the shares of the Common Stock in connection with
the transaction constituting the Change in Control, the value of the
consideration to be delivered in respect of the Make-Whole Premium will be
calculated as follows:

            (i) securities that are traded on a U.S. national securities
      exchange or approved for quotation on The Nasdaq National Market or any
      similar system of automated dissemination of quotations of securities
      prices will be valued based on the average Closing Sale Price or last sale
      price, as applicable, over the ten Trading Day

                                      -75-
<PAGE>

      period ending on the Trading Day immediately preceding the Change in
      Control Purchase Date;

            (ii) other securities, assets or property (other than cash) will be
      valued based on 98% of the average of the fair market value of such
      securities, assets or property (other than cash) as determined by two
      independent nationally recognized investment banks selected by the
      trustee; and

            (iii) 100% of any cash.

      Whenever in this Indenture or Exhibit A annexed hereto there is a
reference, in any context, to the principal of any Security as of any time, such
reference shall be deemed to include reference to the Change in Control Purchase
Price in respect to such Security to the extent that such Change in Control
Purchase Price is, was or would be so payable at such time, plus any applicable
Make-Whole Premium, and express mention of the Change in Control Purchase Price
in any provision of this Indenture shall not be construed as excluding the
Change in Control Purchase Price in those provisions of this Indenture when such
express mention is not made.

      (b) The following are conditions to the Company's election to pay for the
Change in Control Purchase Price and Make-Whole Premium in Common Stock or
Successor Common Stock:

            (i) The shares of Common Stock or Successor Common Stock to be
issued upon repurchase of Securities hereunder:

                  (A) shall not require registration under any federal
securities law before such shares may be freely transferable without being
subject to any transfer restrictions under the Securities Act upon repurchase
or, if such registration is required, such registration shall be completed and
shall become effective prior to the Change in Control Purchase Date; and

                  (B) shall not require registration with, or approval of, any
governmental authority under any state law or any other federal law before
shares may be validly issued or delivered upon repurchase or if such
registration is required or such approval must be obtained, such registration
shall be completed or such approval shall be obtained prior to the Change in
Control Purchase Date.

            (ii) The shares of Common Stock to be listed upon repurchase of
Securities hereunder are, or shall have been, approved for listing on the
principal U.S. national securities exchange on which such Common Stock or
Successor Common Sock is then listed or if not so listed, on the Nasdaq National
Market, in any case, prior to the Change in Control Purchase Date.

            (iii) All shares of Common Stock or Successor Common Stock which may
be issued upon repurchase of Securities will be issued out of the Company's
authorized but unissued Common Stock or out of the successor's or parent's (as
applicable) authorized but unissued Successor Common Stock and will, upon issue,
be duly and validly issued and fully paid and nonassessable and free of any
preemptive or similar rights.

                                      -76-
<PAGE>

            (iv) If any of the conditions set forth in clauses (i) through (iii)
of this Section 12.1(b) are not satisfied in accordance with the terms thereof,
the Change in Control Purchase Price and Make-Whole Premium shall be paid by the
Company only in cash. The Company may not change the form of consideration to be
paid with respect to the Change in Control Purchase Price and Make-Whole Premium
once it has stated such form in the Company Notice, except as described in the
immediately preceding sentence.

      (c) Prior to or on the 30th day after the occurrence of a Change in
Control, the Company, or, at the written request and expense of the Company
prior to or on the 30th day after such occurrence, the Trustee, shall give to
all Holders, in the manner provided in hereof, notice (the "Company Notice") of
the occurrence of the Change in Control and of the purchase right set forth
herein arising as a result thereof. The Company shall also deliver a copy of
such Company Notice to the Trustee. The Company Notice shall include a form of
Change in Control Purchase Notice to be completed by the Holder and shall state:

            (i) briefly, the events causing a Change in Control and the date of
such Change of Control;

            (ii) the date by which the Change in Control Purchase Notice
pursuant to this must be given;

            (iii) the Change in Control Purchase Date;

            (iv) the Change in Control Purchase Price and whether the Change in
Control Purchase Price will be payable in cash, Common Stock or Successor Common
Stock;

            (v) the name and address of the Paying Agent and the Conversion
Agent, if applicable;

            (vi) that Securities as to which a Change in Control Purchase Notice
has been given may be converted pursuant to this Section 12.1 only if the Change
in Control Purchase Notice has been withdrawn in accordance with the terms of
this Indenture;

            (vii) that Securities must be surrendered to the Paying Agent to
collect payment;

            (viii) that the Change in Control Purchase Price for any Security as
to which a Change in Control Purchase Notice has been duly given and not
withdrawn will be paid promptly following the later of the Change in Control
Purchase Date and the time of surrender of such Security as described above;

            (ix) briefly, the procedures the Holder must follow to exercise
rights under this Article Twelve;

            (x) briefly, the conversion rights of the Securities, including the
Conversion Rate and any adjustments thereto;

                                      -77-
<PAGE>

            (xi) the procedures for withdrawing a Change in Control Purchase
Notice;

            (xii) the CUSIP number of the Securities;

            (xiii) whether a Make-Whole Premium shall be paid by the Company and
the form of consideration to be paid in respect of the Make-Whole Premium; and

            (xiv) if a Make-Whole Premium is paid by the Company, that a
Make-Whole Premium shall be paid by the Company on the Change in Control
Purchase Date to Holders of Securities who have converted their Securities into
the Common Stock on or after the date the Company has given the Company Notice
to all Holders and on or before the Change in Control Purchase Date.

      (d) A Holder may exercise its rights specified in this upon delivery of a
written notice of purchase ("Change in Control Purchase Notice") to the Paying
Agent prior to the Change in Control Purchase Date, stating:

            (i) the certificate number of the Security, if any, which the Holder
will deliver to be purchased or the appropriate Depositary procedures if the
Securities are not in certificated form;

            (ii) the portion of the principal amount of the Security which the
Holder will deliver to be purchased, which portion must be $1,000 or any whole
multiple thereof; and

            (iii) that such Security shall be purchased pursuant to the terms
and conditions specified on the reverse side of the Securities and in this
Indenture.

      If the Securities are not in certificated form, a Holder's Change in
Control purchase must comply with the Applicable Procedures.

      The delivery of such Security to the Paying Agent prior to the Change in
Control Purchase Date (together with all necessary endorsements) at the offices
of the Paying Agent shall be a condition to the receipt by the Holder of the
Change in Control Purchase Price therefor; provided, however, that such Change
in Control Purchase Price shall be so paid pursuant to this Section 12.1 only if
the Security so delivered to the Paying Agent shall conform in all respects to
the description thereof set forth in the related Change in Control Purchase
Notice.

      The Company shall purchase from the Holder thereof a portion of a Security
so delivered for purchase if the principal amount of such portion is $1,000 or
an integral multiple of $1,000. Provisions of this Indenture that apply to the
purchase of all of a Security also apply to the purchase of such portion of such
Security.

      Any purchase by the Company contemplated pursuant to the provisions of
this Section 12.1 shall be consummated by the delivery of the consideration to
be received by the Holder promptly following the later of the Change in Control
Purchase Date and the time of delivery of the Security to the Paying Agent in
accordance with this Section 12.1.

                                      -78-
<PAGE>

      Notwithstanding anything herein to the contrary, any Holder delivering to
the Paying Agent the Change in Control Purchase Notice contemplated by this
Section 12.1 shall have the right to withdraw such Change in Control Purchase
Notice at any time prior to the close of business on the Business Day prior to
the Change in Control Purchase Date by delivery of a written notice of
withdrawal to the Paying Agent in accordance with this Article Twelve.

      The Paying Agent shall promptly notify the Company of the receipt by it of
any Change in Control Purchase Notice or written withdrawal thereof.

      The Trustee, subject to the provisions of Section 5.1, shall not at any
time be under any duty or responsibility to any Holder of Securities to
calculate, determine or approve the Change in Control Purchase Price or the
Make-Whole Premium as described in this Section 12.1.

SECTION 12.2 Effect of Change in Control Purchase Notice.

      Upon receipt by the Paying Agent of the Change in Control Purchase Notice
specified in Section 12.1, the Holder of the Security in respect of which such
Change in Control Purchase Notice was given shall (unless such Change in Control
Purchase Notice is withdrawn as specified in the following two paragraphs)
thereafter be entitled to receive solely the Change in Control Purchase Price
with respect to such Security. Such Change in Control Purchase Price (along with
the Make-Whole Premium, if any) shall be paid to such Holder, subject to receipt
of consideration for the Securities by the Paying Agent, promptly following the
later of (x) the Change in Control Purchase Date with respect to such Security
(provided the conditions in Section 12.1 have been satisfied) and (y) the time
of delivery of such Security to the Paying Agent by the Holder thereof in the
manner required by this Article Twelve, as the case may be. Securities in
respect of which a Change in Control Purchase Notice has been given by the
Holder thereof may not be converted pursuant to Article Ten hereof on or after
the date of the delivery of such Change in Control Purchase Notice unless such
Change in Control Purchase Notice has first been validly withdrawn as specified
in the following two paragraphs.

      A Change in Control Purchase Notice may be withdrawn by means of a written
notice of withdrawal delivered to the office of the Paying Agent in accordance
with the Change in Control Purchase Notice at any time prior to the close of
business on the Business Day immediately preceding the Change in Control
Purchase Date specifying:

            (a) the certificate number of the Security in respect of which such
      notice of withdrawal is being submitted or, if not in certificated form,
      the applicable Depositary procedures,

            (b) the principal amount of the Security with respect to which such
      notice of withdrawal is being submitted, and

            (c) the principal amount, if any, of such Security which remains
      subject to the original Change in Control Purchase Notice and which has
      been or will be delivered for purchase by the Company.

      There shall be no purchase of any Securities pursuant to Section 12.1 if
there has occurred (prior to, on or after, as the case may be, the giving, by
the Holders of such Securities,

                                      -79-
<PAGE>

of the required Change in Control Purchase Notice) and is continuing an Event of
Default (other than a default in the payment of the Change in Control Purchase
Price with respect to such Securities). The Paying Agent will promptly return to
the respective Holders thereof any Securities (x) with respect to which a Change
in Control Purchase Notice has been withdrawn in compliance with this Indenture,
or (y) held by it during the continuance of an Event of Default (other than a
default in the payment of the Change in Control Purchase Price with respect to
such Securities) in which case, upon such return, the Change in Control Purchase
Notice with respect thereto shall be deemed to have been withdrawn.

SECTION 12.3 Deposit of Change in Control Purchase Price.

      On or prior to the Change in Control Purchase Date, the Company shall
deposit with the Trustee or with the Paying Agent (or, if the Company or a
Subsidiary or an Affiliate of either of them is acting as the Paying Agent,
shall segregate and hold in trust as provided in Section 8.3) an amount of cash
(in immediately available funds if deposited on such Business Day) or Common
Stock or Successor Common Stock sufficient to pay the aggregate Change in
Control Purchase Price of all the Securities or portions thereof which are to be
purchased as of the Change in Control Purchase Date and an amount in cash,
shares of Common Stock or Successor Common Stock or the consideration used to
pay for the shares of the Common Stock in connection with the Change in Control,
sufficient to pay any Make-Whole Premium.

      If the Trustee or other Paying Agent appointed by the Company, or the
Company or an Affiliate of the Company, if it or such Affiliate is acting as the
Paying Agent, holds cash or shares of Common Stock or Successor Common Stock
sufficient to pay the aggregate Change in Control Purchase Price of all the
Securities or portions thereof that are to be purchased as of the Change in
Control Purchase Date and an amount in cash, shares of Common Stock or Successor
Common Stock, or the consideration used to pay for the shares of the Common
Stock in connection with the Change in Control, sufficient to pay any Make-Whole
Premium, then immediately after the Change in Control Purchase Date (i) such
Securities will cease to be outstanding, (ii) interest on such Securities will
cease to accrue and (iii) all other rights of the holders of such Securities
will terminate other than the right to receive the Change in Control Purchase
Price and the Make-Whole Premium, if any, upon delivery of the Securities,
whether or not book-entry transfer of the Securities has been made or the
Securities have been delivered to the Trustee or Paying Agent.

SECTION 12.4 Securities Purchased in Part.

      Any Security which is to be purchased only in part shall be surrendered at
the office of the Paying Agent (with, if the Company or the Trustee so requires,
due endorsement by, or a written instrument of transfer in form satisfactory to
the Company and the Trustee duly executed by, the Holder thereof or such
Holder's attorney duly authorized in writing) and the Company shall execute and
the Trustee shall authenticate and deliver to the Holder of such Security,
without service charge, a new Security or Securities, of any authorized
denomination as requested by such Holder in aggregate principal amount equal to,
and in exchange for, the portion of the principal amount of the Security so
surrendered which is not purchased.

                                      -80-
<PAGE>

SECTION 12.5 Covenant to Comply with Securities Laws Upon Purchase of
             Securities.

      In connection with any offer to purchase or purchase of Securities under
this Article Twelve (provided that such offer or purchase constitutes an "issuer
tender offer" for purposes of Rule 13e-4 (which term, as used herein, includes
any successor provision thereto) under the Exchange Act at the time of such
offer or purchase), the Company shall (i) comply with Rule 13e-4, Rule 14e-1 and
any other tender offer rules under the Exchange Act which may then be
applicable, (ii) file the related Schedule TO (or any successor schedule, form
or report) or any other schedule required under the Exchange Act, and (iii)
otherwise comply with all federal and state securities laws so as to permit the
rights and obligations under this Article Twelve to be exercised in the time and
in the manner specified herein.

SECTION 12.6 Repayment to the Company.

      The Trustee and the Paying Agent shall return to the Company any cash or
shares of Common Stock or Successor Common Stock, or the consideration used to
pay for the shares of the Common Stock in connection with the Change in Control
that remains unclaimed, together with interest or dividends, if any, thereon,
held by them for the payment of the Change in Control Purchase Price and
Make-Whole Premium, if any; provided, however, that to the extent that the
aggregate amount of cash or shares of Common Stock or Successor Common Stock, or
the consideration used to pay for the shares of the Common Stock in connection
with the Change in Control deposited by the Company pursuant to Section 12.3
exceeds the aggregate Change in Control Purchase Price of the Securities and
Make-Whole Premium, if any, or portions thereof which the Company is obligated
to purchase as of the Change in Control Purchase Date, then promptly after the
Business Day following the Change in Control Purchase Date the Trustee shall
return any such excess to the Company together with interest or dividends, if
any, thereon.

                                ARTICLE THIRTEEN

                                   [RESERVED]

                                ARTICLE FOURTEEN

         HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY; NON-RECOURSE

SECTION 14.1 Company to Furnish Trustee Names and Addresses of Holders.

      The Company will furnish or cause to be furnished to the Trustee:

      (a) semi-annually, not more than 15 days after the Regular Record Date, a
list, in such form as the Trustee may reasonably require, of the names and
addresses of the Holders of Securities as of such Regular Record Date, and

                                      -81-
<PAGE>

      (b) at such other times as the Trustee may reasonably request in writing,
within 30 days after the receipt by the Company of any such request, a list of
similar form and content as of a date not more than 15 days prior to the time
such list is furnished;

provided, however, that no such list need be furnished so long as the Trustee is
acting as Security Registrar.

SECTION 14.2 Preservation of Information.

      (a) The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 14.1 and the names and
addresses of Holders received by the Trustee in its capacity as Security
Registrar. The Trustee may destroy any list furnished to it as provided in
Section 14.1 upon receipt of a new list so furnished.

      (b) After this Indenture has been qualified under the Trust Indenture Act,
the rights of Holders to communicate with other Holders with respect to their
rights under this Indenture or under the Securities, and the corresponding
rights and duties of the Trustee, shall be as provided by the Trust Indenture
Act.

      (c) Every Holder of Securities, by receiving and holding the same, agrees
with the Company and the Trustee that neither the Company nor the Trustee nor
any agent of either of them shall be held accountable by reason of any
disclosure of information as to names and addresses of Holders made pursuant to
the Trust Indenture Act.

SECTION 14.3 No Recourse Against Others.

      No incorporator or any past, present or future director, officer, employee
or direct or indirect stockholder, agent or Subsidiary, as such, of the Company
shall have any liability for any obligations, covenants or agreements of the
Company under the Securities or this Indenture or for any claim based on, in
respect of or by reason of such obligation, covenants or agreements or their
creation. By accepting a Security, each Holder shall waive and release all such
liability. Such waiver and release shall be part of the consideration for the
issue of the Securities.

SECTION 14.4 Reports by Trustee.

      (a) After this Indenture has been qualified under the Trust Indenture Act,
the Trustee shall transmit to Holders such reports concerning the Trustee and
its actions under this Indenture as may be required pursuant to the Trust
Indenture Act at the times and in the manner provided therein. The Trustee
shall, within 60 days after each May 15th following the date of this Indenture,
deliver to Holders a brief report, dated as of such date, that complies with the
provisions of such Section 313(a).

      (b) After this Indenture has been qualified under the Trust Indenture Act,
a copy of each such report shall, at the time of such transmission to Holders,
be filed by the Trustee with each stock exchange upon which the Securities are
listed, with the Commission and with the Company. The Company will promptly
notify the Trustee when the Securities are listed on any stock exchange.

                                      -82-
<PAGE>

SECTION 14.5 Reports by Company.

      After this Indenture has been qualified under the Trust Indenture Act, the
Company shall file with the Trustee and the Commission, and transmit to Holders,
such information, documents and other reports, and such summaries thereof, as
may be required pursuant to the Trust Indenture Act at the times and in the
manner provided therein; provided, however, that any such information, documents
or reports required to be filed with the Commission pursuant to Section 13 or
15(d) of the Exchange Act shall be filed with the Trustee within 15 days after
the same is so required to be filed with the Commission.

      Delivery of such reports, information and documents to the Trustee is for
informational purposes only and the Trustee's receipt thereof shall not
constitute constructive notice of any information contained therein or
determinable from information contained therein, including the Company's
compliance with any of its covenants hereunder (as to which the Trustee is
entitled to rely exclusively on Officers' Certificates).

                            [Signature Page Follows]

                                      -83-
<PAGE>

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

                                        VaxGen, Inc.

                                        By ______________________________
                                           Name:
                                           Title:

                                        U.S. Bank National Association, as
                                        Trustee

                                        By ______________________________
                                           Name:
                                           Title:

                                      -84-
<PAGE>

                                                                       EXHIBIT A

                           [FORM OF FACE OF SECURITY]

      THE NOTE EVIDENCED HEREBY AND THE SHARES OF COMMON STOCK ISSUABLE UPON THE
CONVERSION HEREOF HAVE NOT BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT"), OR OTHER SECURITIES LAWS. NONE OF THIS
NOTE, THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION HEREOF OR ANY INTEREST
OR PARTICIPATION HEREIN MAY BE RE-OFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED,
ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR
UNLESS THE TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT. THE HOLDER OF THIS SECURITY BY ITS
ACCEPTANCE HEREOF (1) REPRESENTS THAT IT IS AN "ACCREDITED INVESTOR" (AS DEFINED
IN REGULATION D UNDER SECURITIES ACT), (2) AGREES THAT IT WILL NOT PRIOR TO (X)
THE DATE WHICH IS TWO YEARS (OR SUCH SHORTER PERIOD OF TIME AS PERMITTED BY RULE
144(K) UNDER THE SECURITIES ACT OR ANY SUCCESSOR PROVISION THEREUNDER) AFTER THE
LATER OF THE ORIGINAL ISSUE DATE HEREOF (OR OF ANY PREDECESSOR OF THIS NOTE) OR
THE LAST DAY ON WHICH VAXGEN, INC. (THE "COMPANY") OR ANY AFFILIATE OF THE
COMPANY WAS THE OWNER OF THIS NOTE (OR ANY PREDECESSOR OF THIS NOTE) AND (Y)
SUCH LATER DATE, IF ANY, AS MAY BE REQUIRED BY APPLICABLE LAW (THE "RESALE
RESTRICTION TERMINATION DATE"), OFFER, SELL OR OTHERWISE TRANSFER THIS NOTE OR
THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION HEREOF EXCEPT (A) TO THE
COMPANY, (B) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED
EFFECTIVE UNDER THE SECURITIES ACT, (C) WHEN AND FOR SO LONG AS THE SECURITIES
ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT, TO A
PERSON IT REASONABLY BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" AS DEFINED IN
RULE 144A UNDER THE SECURITIES ACT THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE
ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE
TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, OR (D) PURSUANT TO ANY OTHER
AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND
(3) AGREES THAT IT WILL GIVE TO EACH PERSON TO WHOM THIS NOTE OR THE SHARES OF
COMMON STOCK ISSUABLE UPON CONVERSION HEREOF ARE TRANSFERRED A NOTICE
SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND; PROVIDED THAT THE COMPANY, THE
TRUSTEE AND THE REGISTRAR SHALL HAVE THE RIGHT PRIOR TO ANY SUCH OFFER, SALE OR
TRANSFER (I) PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY OF AN OPINION OF
COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM AND
(II) IN EACH OF THE FOREGOING CASES, TO REQUIRE THAT A CERTIFICATION OF TRANSFER
IN THE FORM APPEARING ON THE OTHER SIDE OF THE NOTE IS COMPLETED AND

                                      -1-
<PAGE>

DELIVERED BY THIS TRANSFEROR TO THE TRUSTEE. THIS LEGEND WILL BE REMOVED UPON
THE REQUEST OF THE HOLDER AFTER THE RESALE RESTRICTION TERMINATION DATE.

      THIS NOTE, ANY SHARES OF COMMON STOCK ISSUABLE UPON THE CONVERSION HEREOF
AND ANY RELATED DOCUMENTATION MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME
TO MODIFY THE RESTRICTIONS ON RESALES AND OTHER TRANSFERS OF THIS NOTE AND ANY
SUCH SHARES TO REFLECT ANY CHANGE IN APPLICABLE LAW OR REGULATION (OR THE
INTERPRETATION THEREOF) OR IN PRACTICES RELATING TO THE RESALE OR TRANSFER OF
RESTRICTED SECURITIES GENERALLY. THE HOLDER OF THIS NOTE AND SUCH SHARES SHALL
BE DEEMED BY THE ACCEPTANCE OF THIS NOTE AND ANY SUCH SHARES TO HAVE AGREED TO
ANY SUCH AMENDMENT OR SUPPLEMENT.

      [The following legend to be placed on Global Securities after the Rule
144A Availability Date.]

      [THIS NOTE IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITARY OR A
NOMINEE OF THE DEPOSITARY, WHICH MAY BE TREATED BY THE COMPANY, THE TRUSTEE AND
ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS NOTE FOR ALL PURPOSES.

      UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE ISSUER OR
ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME
AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE
TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.]

                                      -2-
<PAGE>

                                  VAXGEN, INC.

          5 1/2% CONVERTIBLE SENIOR SUBORDINATED NOTE DUE APRIL 1, 2010

No. ____________                                                     U.S. $_____

CUSIP No. 922390 AA 7
ISIN NUMBER : US922390AA76

VaxGen, Inc., a corporation duly organized and existing under the laws of the
State of Delaware (herein called the "Company," which term includes any
successor Person under the Indenture referred to on the reverse hereof), for
value received, hereby promises to pay to ________________________________, or
registered assigns, the principal sum of _____________ United States Dollars
(U.S.$ _______________) (which principal amount may from time to time be
increased or decreased to such other principal amounts (which, taken together
with the principal amounts of all other Outstanding Securities, shall not exceed
U.S. $31,500,000 in the aggregate at any time, on April 1, 2010, unless
redeemed, repurchased or converted on an earlier date, and to pay interest
thereon, from April 5, 2005, or from the most recent Interest Payment Date (as
defined below) to which interest has been paid or duly provided for,
semiannually in arrears on April 1 and October 1 in each year (each, an
"Interest Payment Date"), commencing October 1, 2005, at the rate of 5 1/2% per
annum, until the principal hereof is due, and at the rate then in effect on any
overdue principal and premium, if any, and, to the extent permitted by law, on
any overdue interest. The interest so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the Person in whose name this Security (or one or more Predecessor
Securities) is registered at the close of business on the Regular Record Date
for such interest, which shall be the March 15 and September 15 (whether or not
a Business Day), as the case may be, next preceding such Interest Payment Date.
Except as otherwise provided in the Indenture, any such interest not so
punctually paid or duly provided for will forthwith cease to be payable to the
Holder on such Regular Record Date and may either be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on a Special Record Date for the payment of such Defaulted
Interest to be fixed by the Company, notice whereof shall be given to Holders of
Registered Securities not less than ten days prior to such Special Record Date,
or be paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Securities may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in the Indenture. Payments of principal shall be made upon the
surrender of this Security at the option of the Holder at the Corporate Trust
Office or at such other office or agency of the Company as may be designated by
it for such purpose in the Borough of Manhattan, The City of New York, in such
coin or currency of the United States of America as at the time of payment shall
be legal tender for the payment of public and private debts, or at such other
offices or agencies as the Company may designate, by United States Dollar check
drawn on, or wire transfer to, a United States Dollar account (such a wire
transfer to be made only to a Holder of an aggregate principal amount of
Registered

                                      -3-
<PAGE>

Securities in excess of U.S. $2,000,000 and only if such Holder shall have
furnished wire instructions in writing to the Trustee no later than 15 days
prior to the relevant payment date) maintained by the payee. Payment of interest
on this Security may be made by United States Dollar check mailed to the address
of the Person entitled thereto as such address shall appear in the Security
Register or, upon written application by the Holder to the Security Registrar
setting forth wire instructions not later than the relevant Record Date, by wire
transfer to a United States dollar account (such a wire transfer to be made only
to a Holder of an aggregate principal amount of Registered Securities in excess
of U.S. $2,000,000 and only if such Holder shall have furnished wire
instructions in writing to the Trustee no later than 15 days prior to the
relevant payment date) maintained by the payee.

      Except as specifically provided herein and in the Indenture, the Company
shall not be required to make any payment with respect to any tax, assessment or
other governmental charge imposed by any government or any political subdivision
or taxing authority thereof or therein.

      Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

      Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof or an Authenticating Agent by the
manual signature of one of their respective authorized signatories, this
Security shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

      IN WITNESS WHEREOF, the Company has caused this Security to be duly
executed.

                                        VAXGEN, INC.

                                        By: ____________________________________

                                            Name: ______________________________

                                            Title: _____________________________

Dated: April 5, 2005

                                      -4-
<PAGE>

      This is one of the Securities referred to in the within-mentioned
Indenture.

U.S. Bank National Association,
as Trustee

By: __________________________________
        Authorized Signatory

                                      -5-
<PAGE>

                          [FORM OF REVERSE OF SECURITY]

      This Security is one of a duly authorized issue of securities of the
Company designated as its "5 1/2% Convertible Senior Subordinated Notes due
April 1, 2010" (herein called the "Securities"), limited in aggregate principal
amount to U.S. $31,500,000, issued and to be issued under an Indenture, dated as
of April 5, 2005 (herein called the "Indenture"), between the Company and U.S.
Bank National Association, as Trustee (herein called the "Trustee," which term
includes any successor trustee under the Indenture), to which Indenture and all
indentures supplemental thereto reference is hereby made for a statement of the
respective rights, limitations of rights, duties and immunities thereunder of
the Company, the Trustee, the holders of Senior Debt and the Holders of the
Securities and of the terms upon which the Securities are, and are to be,
authenticated and delivered. As provided in the Indenture and subject to certain
limitations set forth therein, Registered Securities are exchangeable for a like
aggregate principal amount of Registered Securities of any authorized
denominations as requested by the Holder surrendering the same upon surrender of
the Registered Security or Registered Securities to be exchanged at the
Corporate Trust Office. The Trustee upon such surrender by the Holder will issue
the new Registered Securities in the requested denominations.

      No sinking fund is provided for the Securities.

      The Securities are subject to redemption at the option of the Company at
any time prior to April 1, 2010 ("Provisional Redemption"), in whole or in part,
upon not less than 30 nor more than 60 days' notice to the Holders prior to the
Redemption Date at a Redemption Price equal to 100% of the principal amount,
together, in each case, with accrued and unpaid interest (including, Liquidated
Damages, if any) to, but excluding, the Redemption Date plus the Interest
Make-Whole Payment; provided, that (a) the Closing Sale Price of the Common
Stock has exceeded 150% of the Conversion Price then in effect for at least 20
Trading Days within a period of 30 consecutive Trading Days ending on the
Trading Date immediately before the date of mailing of the Redemption Notice and
(2) the Registration Statement covering resale of the Securities and the
Underlying Common Stock (as defined in the Purchase Agreement) is effective and
available for use for the 30 days following the Redemption Day, unless
registration thereof is not required. Upon any Provisional Redemption, the
Company will pay to the Holders cash (except as set forth below) with respect to
the Securities called for Provisional Redemption, including any Security
converted after the date of the notice of Provisional Redemption and before to
the date of the Provisional Redemption. Notwithstanding the foregoing, the
Company may make the Interest Make-Whole Payment in (a) cash, (b) subject to
certain conditions set forth below in the Indenture, Common Stock or Successor
Common Stock or (c) a combination of cash and Common Stock or Successor Common
Stock.

      In the event of a redemption of the Securities, the Company will not be
required (a) to register the transfer or exchange of Registered Securities for a
period of 15 days immediately preceding the date notice is given identifying the
serial numbers of the Securities called for such redemption (it being understood
that the Company will not be required to identify the serial

                                      -6-
<PAGE>

numbers of Outstanding Securities if all such Securities are called for
redemption) or (b) to register the transfer or exchange of any Registered
Security, or portion thereof, called for redemption.

      In any case where the due date for the payment of the principal of,
premium, if any, or interest (including Liquidated Damages, if any) on any
Security or the last day on which a Holder of a Security has a right to convert
his Security shall be, at any Place of Payment or Place of Conversion, as the
case may be, a day on which banking institutions at such Place of Payment or
Place of Conversion are authorized or obligated by law or executive order to
close, then payment of principal, premium, if any, or interest (including
Liquidated Damages, if any) or delivery for conversion of such Security need not
be made on or by such date at such place but may be made on or by the next
succeeding day at such place which is not a day on which banking institutions
are authorized or obligated by law or executive order to close, with the same
force and effect as if made on the date for such payment or the date fixed for
redemption or repurchase, or by such last day for conversion, and no interest
shall accrue on the amount so payable for the period from and after such due
date.

      Subject to and upon compliance with the provisions of the Indenture, the
Holder of this Security is entitled, at its option, at any time following the
original issue date of the Securities and on or before the close of business on
April 1, 2010, or in case this Security or a portion hereof is called for
redemption or the Holder hereof has exercised his right to require the Company
to repurchase this Security or such portion hereof, then in respect of this
Security until and including, but (unless the Company defaults in making the
payment due upon redemption or repurchase, as the case may be) not after, the
close of business on the Business Day immediately preceding the Redemption Date
or the Change in Control Purchase Date, as the case may be, to convert this
Security or any portion of the principal amount hereof that is an integral
multiple of U.S. $1,000 (provided that the unconverted portion of such principal
amount is U.S. $1,000 or any integral multiple of U.S. $1,000 in excess thereof)
into fully paid and nonassessable shares of Common Stock of the Company at an
initial Conversion Rate of 67.7507 shares of Common Stock per $1,000 principal
amount of Securities (or at the current adjusted Conversion Rate if an
adjustment has been made as provided in the Indenture) by surrender of this
Security, duly endorsed or assigned to the Company or in blank and, in case such
surrender shall be made during the period from the close of business on any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date (except if this Security has been called
for redemption on a Redemption Date or is repurchasable on a Change in Control
Purchase Date, with the consequence that the conversion right of such Security
would terminate between such Regular Record Date and the close of business on
such Interest Payment Date), also accompanied by payment in New York Clearing
House or other funds acceptable to the Company of an amount equal to the
interest payable on such Interest Payment Date on the principal amount of this
Security then being converted, and also the conversion notice hereon duly
executed, to the Company at the Corporate Trust Office, or at such other office
or agency of the Company, subject to any laws or regulations applicable thereto
and subject to the right of the Company to terminate the appointment of any
Conversion Agent (as defined below) as may be

                                      -7-
<PAGE>

designated by it for such purpose in the Borough of Manhattan, The City of New
York, or at such other offices or agencies as the Company may designate (each a
"Conversion Agent"), provided, further, that in case surrender of this Security
for conversion shall be made during the period from the close of business on any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date and if this Security or portion hereof
has been called for redemption on a Redemption Date or is repurchasable on a
Change in Control Purchase Date, with the consequence that the conversion right
of such Security would terminate between such Regular Record Date and the close
of business on such Interest Payment Date, then the Holder of this Security will
be entitled to receive the interest accruing hereon from the Interest Payment
Date next preceding the date of such conversion to such succeeding Interest
Payment Date and shall not be required to pay such interest upon surrender of
this Security for conversion. Subject to the provisions of the preceding
sentence and, in the case of a conversion after the close of business on the
Regular Record Date next preceding any Interest Payment Date and on or before
the close of business on such Interest Payment Date, to the right of the Holder
of this Security (or any Predecessor Security of record as of such Regular
Record Date) to receive the related installment of interest to the extent and
under the circumstances provided in the Indenture, no cash payment or adjustment
is to be made on conversion for interest accrued hereon from the Interest
Payment Date next preceding the day of conversion, or for dividends on the
Common Stock issued on conversion hereof. The Company shall thereafter deliver
to the Holder the fixed number of shares of Common Stock (together with any cash
adjustment or rights or warrants, as provided in the Indenture) into which this
Security is convertible and such delivery will be deemed to satisfy the
Company's obligation to pay the principal amount of this Security. No fractions
of shares or scrip representing fractions of shares will be issued on
conversion, but instead of any fractional interest (calculated to the nearest
1/100th of a share) the Company shall pay a cash adjustment as provided in the
Indenture. The Conversion Rate is subject to adjustment as provided in the
Indenture. In addition, the Indenture provides that in case of certain
consolidations or mergers to which the Company is a party or the conveyance,
transfer, sale or lease (other than a grant of security interest) of all or
substantially all of the property and assets of the Company, the Indenture shall
be amended, without the consent of any Holders of Securities, so that this
Security, if then Outstanding, will be convertible thereafter, during the period
this Security shall be convertible as specified above, only into the kind and
amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, transfer, sale or lease by a holder of the
number of shares of Common Stock of the Company into which this Security could
have been converted immediately prior to such consolidation, merger, conveyance,
transfer, sale or lease (assuming such holder of Common Stock is not a
Constituent Person or an Affiliate of a Constituent Person, failed to exercise
any rights of election and received per share the kind and amount received per
share by a plurality of Non-electing Shares). No adjustment in the Conversion
Rate will be made until such adjustment would require an increase or decrease of
at least one percent of such rate, provided that any adjustment that would
otherwise be made will be carried forward and taken into account in the
computation of any subsequent adjustment.

                                      -8-
<PAGE>

      The Holder of this Security (including any Person that has a beneficial
interest in this Security) and the Common Stock issuable upon conversion hereof
is entitled to the registration rights set forth in a Purchase Agreement, dated
as of March 30, 2005 (the "Purchase Agreement"), executed by the Company and the
Holder. Pursuant to the Purchase Agreement, the Company has agreed for the
benefit of the Holders from time to time of Registered Securities and the Common
Stock issuable upon conversion thereof, in each case, that are Registrable
Securities, at the Company's expense, (a) to file with the Commission, as soon
as reasonably practicable, but in no event later than 30 days after the first
date the Company becomes current in its reporting requirements under the
Exchange Act, a registration statement (the "Registration Statement") with
respect to resales of the Registrable Securities, (b) thereafter to use its
reasonable best efforts to cause the Registration Statement to be declared
effective by the Commission on or prior to (1) 90 days following the filing of
such Registration Statement if there is no review of the Registration Statement
by the Commission or (2) 120 days following the filing of such Registration
Statement if there is a review of the Registration Statement by the Commission
and (c) prepare and file with the Commission such amendments and supplements to
the Registration Statement and the prospectus used in connection therewith as
may be necessary to keep the Registration Statement continuously effective until
the earlier of (1) the second anniversary of the issuance of the Securities and
(2) such time as all Registrable Securities held by Holders have been sold
pursuant to the Registration Statement. The Company is required to pay
Liquidated Damages to holders of Registrable Securities for failure to comply
with the foregoing registration obligations, all as more fully set forth in the
Purchase Agreement.

      Whenever in this Security there is a reference, in any context, to the
payment of the principal of, premium, if any, or interest on, or in respect of,
any Security such mention shall be deemed to include mention of the payment of
Liquidated Damages payable as described in the Purchase Agreements to the extent
that, in such context, Liquidated Damages are, were or would be payable in
respect of this Security pursuant to the Purchase Agreement, and an express
mention of the payment of Liquidated Damages (if applicable) in any provisions
of this Security shall not be construed as excluding Liquidated Damages in those
provisions of this Security where such express mention is not made. If the
Holder of this Security (including any Person that has a beneficial interest in
this Security) elects to sell this Security pursuant to the Registration
Statement then, by its acceptance hereof, such Holder of this Security agrees to
be bound by the terms of the Purchase Agreements relating to the Registrable
Securities which are the subject of such election.

      If a Change in Control occurs, the Holder of this Security, at the
Holder's option, shall have the right, in accordance with the provisions of the
Indenture, to require the Company to repurchase this Security (or any portion of
the principal amount hereof that is equal to U.S. $1,000 or any greater integral
multiple of U.S. $1,000) for cash at a Change in Control Purchase Price equal to
100% of the principal amount thereof plus interest accrued (including any
Liquidated Damages, if any) to, but excluding, the Change in Control Purchase
Date plus, in certain instances, the Make-Whole Premium. At the option of the
Company, the Change in Control Purchase Price and/or the Make-Whole Premium may
be paid in cash or, subject to the

                                      -9-
<PAGE>

conditions provided in the Indenture, by delivery of shares of Common Stock or
Successor Common Stock or in a combination of cash and Common Stock or Successor
Common Stock, having a fair market value equal to the Change in Control Purchase
Price or Make-Whole Premium (as applicable). For purposes of this paragraph, (a)
the value of the Common Stock or the Successor Common Stock to be delivered in
respect of the Change in Control Purchase Price shall be deemed to be equal to
95% of the average of the Closing Sale Prices per share for the five consecutive
Trading Days ending on and including the third day prior to the Change in
Control Purchase Date; provided that the Change in Control Purchase Price may
only be paid in Successor Common Stock if such common stock is traded on The
Nasdaq National Market or other U.S. national securities exchange and (b) the
value of the Common Stock or the Successor Common Stock to be delivered in
respect of the Make-Whole Premium shall be deemed equal to 95% of the average of
the Closing Sale Prices per share for the ten Trading Day period ending on the
Trading Day immediately preceding the Change in Control Purchase Date. The
Company may pay the Make-Whole Premium in shares of Common Stock or the
Successor Common Stock only if the information necessary to calculate the
Closing Sale Price per share is published in a daily newspaper of general
circulation or by other appropriate means. Whenever in this Security there is a
reference, in any context, to the principal of any Security as of any time, such
reference shall be deemed to include reference to the Change in Control Purchase
Price payable in respect of such Security to the extent that such Change in
Control Purchase Price is, was or would be so payable at such time, and express
mention of the Change in Control Purchase Price in any provision of this
Security shall not be construed as excluding the Change in Control Purchase
Price so payable in those provisions of this Security when such express mention
is not made; provided, however, that, for the purposes of the paragraph below
concerning the consequences of an Event of Default, such reference shall be
deemed to include reference to the Change in Control Purchase Price only to the
extent the Change in Control Purchase Price is payable in cash.

      [The following paragraph shall appear in each Global Security:

      In the event of a deposit or withdrawal of an interest in this Security,
including an exchange, transfer, redemption, repurchase or conversion of this
Security in part only, the Trustee, as custodian of the Depositary, shall make
an adjustment on its records to reflect such deposit or withdrawal in accordance
with the Applicable Procedures.]

      [The following paragraph shall appear in each Security that is not a
Global Security:

      In the event of redemption, repurchase or conversion of this Security in
part only, a new Security or Securities for the unredeemed, unrepurchased or
unconverted portion hereof will be issued in the name of the Holder hereof.]

      The indebtedness evidenced by this Security is, to the extent and in the
manner provided in the Indenture, subordinate and subject in right of payment to
the prior payment in full in cash or Cash Equivalents of all Senior Debt of the
Company, and this Security is issued subject to

                                      -10-
<PAGE>

such provisions of the Indenture with respect thereto. Each Holder of this
Security, by accepting the same,

      (a) agrees to and shall be bound by such provisions,

      (b) authorizes and directs the Trustee on his behalf to take such action
as may be necessary or appropriate to effectuate the subordination so provided,
and

      (c) appoints the Trustee his attorney-in-fact for any and all such
purposes.

      If an Event of Default shall occur and be continuing, the principal of all
the Securities, together with accrued and unpaid interest, if any, to the date
of declaration, may be declared due and payable in the manner and with the
effect provided in the Indenture. Upon payment (i) of the amount of principal so
declared due and payable, together with accrued and unpaid interest to the date
of declaration, and (ii) of interest on any overdue principal and, to the extent
permitted by applicable law, overdue interest, all of the Company's obligations
in respect of the payment of the principal of and interest on the Securities
shall terminate.

      The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities under the Indenture at
any time by the Company and the Trustee with the written consent of the Holders
of a majority in principal amount of the Securities at the time Outstanding. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the Securities at the time Outstanding, on
behalf of the Holders of all the Securities, to waive compliance by the Company
with certain provisions of the Indenture and certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the Holder of
this Security shall be conclusive and binding upon such Holder and upon all
future Holders of this Security and of any Security issued in exchange herefor
or in lieu hereof, whether or not notation of such consent or waiver is made
upon this Security or such other Security.

      As provided in and subject to the provisions of the Indenture, the Holder
of this Security shall not have the right to institute any proceeding with
respect to the Indenture or for the appointment of a receiver or trustee or for
any other remedy thereunder, unless such Holder shall have previously given the
Trustee written notice of a continuing Event of Default, the Holders of not less
than 25% in principal amount of the Outstanding Securities shall have made
written request to the Trustee to institute proceedings in respect of such Event
of Default as Trustee and furnished the Trustee indemnity reasonably acceptable
to it, the Trustee shall have failed to institute any such proceeding for 60
days after receipt of such notice, request and offer of indemnity, and the
Trustee has not received any direction inconsistent with such written request
from the Holders of a majority of the aggregate principal amount of the
Outstanding Securities during such 60 day period. The foregoing shall not apply
to any suit instituted by the Holder of this Security for the enforcement of any
payment of principal hereof, premium, if any,

                                      -11-
<PAGE>

Liquidated Damages, if any, or interest hereon on or after the respective due
dates expressed herein or for the enforcement of the right to convert this
Security as provided in the Indenture.

      No reference herein to the Indenture and no provision of this Security or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal of, premium, if any, Liquidated
Damages, if any, and interest on this Security at the times, places and rate,
and in the coin or currency, herein prescribed or to convert this Security as
provided in the Indenture.

      As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of Registered Securities is registrable on the Security
Register upon surrender of a Registered Security for registration of transfer at
the Corporate Trust Office of the Trustee or at such other office or agency of
the Company as may be designated by it for such purpose in the Borough of
Manhattan, The City of New York, or at such other offices or agencies as the
Company may designate, duly endorsed by, or accompanied by a written instrument
of transfer in form satisfactory to the Company and the Security Registrar duly
executed by, the Holder thereof or his attorney duly authorized in writing, and
thereupon one or more new Registered Securities, of authorized denominations and
for the same aggregate principal amount, will be issued to the designated
transferee or transferees by the Registrar. No service charge shall be made for
any such registration of transfer or exchange, but the Company may require
payment of a sum sufficient to recover any tax or other governmental charge
payable in connection therewith.

      Prior to due presentation of a Registered Security for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name such Registered Security is registered as the
owner thereof for all purposes, whether or not such Security be overdue, and
neither the Company, the Trustee nor any such agent shall be affected by notice
to the contrary.

      Interest on the Securities shall be computed on the basis of a 360-day
year of twelve 30-day months. The Indenture and this Security shall be governed
by and construed in accordance with the laws of the State of New York, United
States of America, including, without limitation, Section 5-1401 of the New York
General Obligations Law.

      All terms used in this Security, which are defined in the Indenture, shall
have the meanings assigned to them in the Indenture.

                                      -12-
<PAGE>

                                                                       EXHIBIT B

            ELECTION OF HOLDER TO REQUIRE CHANGE IN CONTROL PURCHASE

      1. Pursuant to Section 12.1 of the Indenture, the undersigned hereby
elects to have this Security purchased by the Company.

      2. The undersigned hereby directs the Trustee or the Company to pay it or
___________________ an amount in cash equal to 100% of the principal amount to
be purchased (as set forth below), plus interest accrued to the Change in
Control Purchase Date and the Make-Whole Premium (if applicable) or, at the
Company's election, Common Stock or Successor Common Stock, valued as set forth
in the Indenture.

                                        Dated: _________________________________

                                        ________________________________________
                                        Signature
                                        Name of Holder: ________________________

                                        Signature Guaranteed

                                        ________________________________________
                                        Signature must be guaranteed by a
                                        participant in a recognized signature
                                        medallion program or other signature
                                        guarantor acceptable to the Trustee.

Principal amount to be purchased:

__________________________________________
(must be equal to U.S. $1,000 or any
greater integral multiple of U.S. $1,000):

Remaining principal amount following such purchase:

__________________________________________

NOTICE: The signature to the foregoing election must correspond to the name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.

                                      B-1
<PAGE>

                                                                       EXHIBIT C

                                CONVERSION NOTICE

      The undersigned Holder of this Security hereby irrevocably exercises the
option to convert this Security, or any portion of the principal amount hereof
(which is an integral multiple of U.S. $1,000) below designated, into shares of
Common Stock in accordance with the terms of the Indenture referred to in this
Security and directs that such shares, together with a check in payment for any
fractional share and any Securities representing any unconverted principal
amount hereof, be delivered to and be registered in the name of the undersigned
unless a different name has been indicated below. If shares of Common Stock or
Securities are to be registered in the name of a Person other than the
undersigned, the undersigned will pay all transfer taxes payable with respect
thereto. Any amount required to be paid by the undersigned on account of
interest accompanies this Security.

Dated: _______________________________

                                                       Signature

                                        Name of Holder:
                                        Title of Signatory:

If shares or Registered Securities are  If only a portion of the Securities is
to be registered in the name of a       to be converted, please indicate:
Person other than the Holder, please
print such Person's name and address:
                                        1.    Principal amount to be
                                              converted:

                                              U.S. $_________________________
______________________________________        (any integral multiple of U.S.
______________________________________        $1,000)
              Address
                                        2.    Principal amount and
______________________________________        denomination of Registered
Social Security or other Taxpayer             Securities representing
Identification Number, if any                 unconverted principal amount to
                                              be issued:
Signature Guarantee:

                                              Amount: U.S. $_________________
______________________________________
Signature must be guaranteed by a
participant in a recognized signature
guaranty medallion program or other
signature guarantor acceptable to the
Trustee.

                                       C-1

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