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EXHIBIT 4
JOINT FILING AGREEMENT
Each of the undersigned hereby acknowledges and agrees, in compliance
with the provisions of Rule 13d-1(k)(1) promulgated under the Securities
Exchange Act of 1934, as amended, that the Schedule 13D to which this Agreement
is attached as an Exhibit (the "Schedule 13D"), and any amendments thereto, will
be filed with the Securities and Exchange Commission jointly on behalf of the
undersigned.
This Agreement may be executed in one or more counterparts.
Dated: July 17, 2000
PERSEUS-SOROS BIOPHARMACEUTICAL FUND,
LP
By: Perseus-Soros Partners, LLC,
General Partner
By: SFM Participation, LP,
Member
By: SFM AH, Inc.,
General Partner
By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Vice President
PERSEUS-SOROS PARTNERS, LLC
By: SFM Participation, LP,
Member
By: SFM AH, Inc.,
General Partner
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By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Vice President
PERSEUS BIOTECH FUND PARTNERS, LLC
By: Rappahannock Investment Company,
Managing Member
By: /s/ Frank H. Pearl
----------------------------
Name: Frank H. Pearl
Title: Sole Shareholder
RAPPAHANNOCK INVESTMENT COMPANY
By: /s/ Frank H. Pearl
----------------------------
Name: Frank H. Pearl
Title: Sole Shareholder
MR. FRANK H. PEARL
By: /s/ Frank H. Pearl
----------------------------
Name: Frank H. Pearl
SFM PARTICIPATION, LP
By: SFM AH, Inc.,
General Partner
By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Vice President
SFM AH, INC.
By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Vice President
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MR. GEORGE SOROS
By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Attorney-in-fact
SOROS FUND MANAGEMENT LLC
By: /s/ Michael C. Neus
----------------------------
Name: Michael C. Neus
Title: Deputy General Counsel
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