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Exhibit 4.1  

 
 

AMENDMENT NO. 1 TO
  AMENDED AND RESTATED RIGHTS AGREEMENT    
    

        THIS AMENDMENT NO. 1 TO RIGHTS AGREEMENT (this "Amendment") is dated as of June 20, 2003, and is made
between IDEC PHARMACEUTICALS CORPORATION, a Delaware corporation (the "Company"), and  MELLON INVESTOR SERVICES LLC, a New Jersey limited liability company, as Rights Agent (f/k/a ChaseMellon Shareholder Services, LLC, the
"Rights Agent"), with reference to the following facts: 

        A.    The
Company and the Rights Agent entered into that certain Amended and Restated Rights Agreement, dated as of July 26, 2001 (the "Rights
Agreement"), in order to make certain modifications to the Company's existing stockholder rights plan (as more fully described in the Right Agreement). Capitalized terms used
without definition herein have the meanings ascribed to such terms in the Rights Agreement. 

        B.    The
Board of Directors of the Company has determined that (i) it is in the best interests of the Company to enter into that certain Agreement and Plan of Merger
(as it may be amended from time to time, the "Merger Agreement") by and among the Company, Biogen, Inc., a Massachusetts corporation
("Bridges"), and Bridges Merger Corporation, a Massachusetts corporation and a wholly owned subsidiary of the Company ("Merger
Sub"), pursuant to which it is proposed that Merger Sub will merge with and into Bridges (the "Merger"), with the Merger to
become effective as set forth in the Merger Agreement (the time of such effectiveness being the "Effective Time"), and (ii) it is desirable for
the Company to make certain clarifications with respect to the Rights Agreement in connection with the execution of the Merger Agreement. 

        C.    Pursuant
to Section 27 of the Rights Agreement, the Company and the Rights Agent may amend the Rights Agreement at
any time prior to a Distribution Date (which has not yet occurred). 

        NOW,
THEREFORE, the Company and the Rights Agent hereby agree as follows: 

        1.    Beneficial Ownership. Notwithstanding the provisions of  Section 1(c) and Section 28 of the Rights Agreement, at
no time prior to the Effective
Time shall Persons that Beneficially Own shares of common stock, par value $0.01 per share, of Bridges ("Bridges Capital Stock") be deemed, as a result
of the Merger Agreement or the transactions and arrangements contemplated thereby, to Beneficially Own (or to be the Beneficial Owner or to have Beneficial Ownership of) shares of Common Stock into
which shares of Bridges Capital Stock may (pursuant to the Merger Agreement) be converted, or which may (pursuant to the Merger Agreement) otherwise be issuable, as a result of the Merger. 

        2.    Effectiveness. This Amendment shall be deemed effective as of the date first set forth above, as if executed and delivered
on such date. Except as amended hereby, the Rights Agreement shall remain in full force and effect and otherwise be unaffected hereby. 

        3.    Governing Law. This Amendment shall be deemed to be a contract made under the laws of the State of Delaware and for all
purposes shall be governed by and construed in accordance with the laws of such state applicable to contracts to be made and to be performed entirely within such state. 

 

        4.    Counterparts. This Amendment may be executed in counterparts, each of which shall be deemed an original, and all of which
together shall constitute one instrument. 

        IN
WITNESS WHEREOF, this Amendment is executed as of the date first set forth above. 

	
THE COMPANY:
 IDEC PHARMACEUTICALS CORPORATION,

a Delaware corporation	
 	
THE RIGHTS AGENT:
 MELLON INVESTOR SERVICES LLC,

a New Jersey limited liability company
	

 	

 	
 	

 	

 
	By:	/s/  JOHN DUNN      
	 	By:	/s/  SHARON KNEPPER      

	

 	

 	
 	

 	

 
	Name:	John Dunn
	 	Name:	Sharon Knepper

	

 	

 	
 	

 	

 
	Title:	Senior Vice President
	 	Title:	Vice President

2

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AMENDMENT NO. 1 TO AMENDED AND RESTATED RIGHTS AGREEMENTQuickLinks
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Exhibit 4.1    
    

Rights Certificate Number:                   

Number of Rights:                   

RIGEL PHARMACEUTICALS, INC.  

 FORM OF SUBSCRIPTION RIGHTS CERTIFICATE

Evidencing Subscription Rights to Purchase Shares of Common Stock of Rigel Pharmaceuticals, Inc.

Subscription Price: $0.64 per Share  

THE
SUBSCRIPTION RIGHTS WILL EXPIRE IF NOT EXERCISED ON OR BEFORE 5:00 P.M. CENTRAL DAYLIGHT TIME ON                        ,
2003, UNLESS EXTENDED BY RIGEL PHARMACEUTICALS, INC. 

Dear
Stockholder: 

As
the registered owner of this subscription rights certificate, you are the owner of the number of subscription rights (the "Rights") shown above. You have been issued, at no charge, one
non-transferable Right for each share of Rigel Pharmaceuticals, Inc. ("Rigel") common stock, par value $0.001 per share ("Common Stock"), that you held on April 29, 2003. The
Rights entitle you to subscribe for and purchase shares of Common Stock. Each Right allows the holder thereof to subscribe for              of a share of Common Stock
(the "Basic Subscription Privilege"), rounded down to the nearest whole number at the cash price of $0.64 per share (the "Subscription Price"). In addition, each holder of Rights who exercises their
Basic Subscription Privilege in full will be eligible to subscribe (the "Over-Subscription Privilege") at the same cash price of $0.64 per share for additional shares of Common Stock that
are not otherwise purchased pursuant to the exercise of Rights under the Basic Subscription Privilege, subject to availability and pro ration as described in the prospectus. For a more complete
description of the terms and conditions of these subscription rights,
please refer to the prospectus and the "Instructions as to Use of Rigel Pharmaceuticals, Inc. Subscription Rights Certificates" accompanying this subscription rights certificate. 

THESE SUBSCRIPTION RIGHTS ARE NON-TRANSFERABLE

CHECK AND COMPLETE

	

	

o	
 	

PART 1A—TO EXERCISE BASIC SUBSCRIPTION PRIVILEGE: The undersigned hereby irrevocably subscribes for the number of shares indicated below upon the terms and conditions specified in the prospectus, receipt of which is hereby
acknowledged.
	

 	
 	

Number of shares subscribed for             , at $0.64 per share = $            
	

o	
 	

PART 1B—TO EXERCISE OVER-SUBSCRIPTION PRIVILEGE: The undersigned hereby irrevocably over-subscribes for              shares, upon the terms and conditions provided in the
prospectus. (The Over-Subscription Privilege may only be exercised if the Basic Subscription Privilege has been exercised in full by the undersigned and if other holders of Rights do not exercise their Basic Subscription Privilege in full. The
undersigned hereby represents and certifies that their Basic Subscription Privilege has been exercised in full.)
	

 	
 	

Number of shares over-subscribed for             , at $0.64 per share = $            
	

 	
 	
Total Amount Enclosed (#1A and #1B): $            
	

	
DELIVERY OPTIONS FOR SUBSCRIPTION RIGHTS CERTIFICATE
	

If by mail, hand or overnight courier, to:

Well Fargo Bank, MN, N.A.

161 North Concord Exchange

South St. Paul, MN 55075

Attention: Corporate Actions, Rigel Pharmaceuticals, Inc. Rights Offering
	
DELIVERY TO ANY ADDRESS OR BY ANY METHOD OTHER THAN THOSE

SET FORTH ABOVE DOES NOT CONSTITUTE VALID DELIVERY.
	

I acknowledge that I have received the prospectus for this rights offering and I hereby irrevocably subscribe for the number of shares indicated above on the terms and
conditions specified in the prospectus.

	 	 	READ INSTRUCTIONS BEFORE SIGNING
	

 	
 	

    
 SUBSCRIBER'S SIGNATURE
	

 	
 	

    
 ADDITIONAL SIGNATURE (if jointly held)

IMPORTANT: The signature(s) must correspond with the name(s) as printed on the reverse of this Subscription Rights Certificate in every particular,
without alteration or enlargement, or any other change whatsoever. 

METHOD OF PAYMENT (CHECK ONE)  

	o
	Uncertified
personal check payable to "Well Fargo Bank, MN, N.A., as Subscription Agent." Please note that funds paid by uncertified
personal check may take at least five business days to clear. Accordingly, holders of Rights who wish to pay the purchase price by means of an uncertified personal check are urged to make payment
sufficiently in advance of the expiration date to ensure that such payment is received and clears by the expiration date, and are urged to consider payment by means of a certified or cashier's check,
money order or wire transfer of funds.

	o
	Certified
or cashier's check drawn on a U.S. bank or money order, payable to "Wells Fargo Bank, MN, N.A., as Subscription Agent."

	o
	Wire
transfer of immediately available funds directed to the account maintained by Wells Fargo Bank, MN, N.A. at: 

161
North Concord Exchange

South St. Paul, MN 55075

Attn: Corporate Actions, Rigel Pharmaceuticals, Inc. Rights Offering 

ABA
No. 091000019

Account No. 1067899 

Account
Name: Rigel Pharmaceuticals, Inc. Subscription 

If
you do not indicate the number of Rights being exercised, or do not forward full payment of the total Subscription Price for the number of Rights that you indicate are being exercised, then you
will be deemed to have exercised the Basic Subscription Privilege with respect to the maximum number of Rights that may be exercised for the aggregate Subscription Price payment you delivered to the
subscription agent. If your aggregate Subscription Price payment is greater than the amount you owe for your subscription, you will be deemed to have exercised the full Basic Subscription Privilege
and the Over-Subscription Privilege to purchase the maximum number of shares of Common Stock with your overpayment. If we do not apply your full Subscription Price payment to your purchase
of shares of Common Stock, we will return the excess amount to you by mail without interest or deduction as soon as practicable after the expiration date of the rights offering. 

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Exhibit 4.1

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