MURRAY FRANK LLP is investigating breaches of fiduciary duties by certain members of the Board of Directors of Allos Therapeutics, Inc., (NASDAQ: ALTH) (“Allos” or the “Company”) regarding the acquisition of the Company by AMAG Pharmaceuticals, Inc., (NASDAQ: AMAG) (“AMAG”).

On July 20, 2011, Allos and AMAG announced that they had entered into an agreement under which Allos would be acquired by AMAG in a transaction valued at approximately $686 million. Pursuant to the terms of the agreement, Allos shareholders will receive a fixed ratio of 0.1282 shares of AMAG stock for each share of Allos stock they own, a value of $2.44 per share of Allos common stock based on the closing price of AMAG’s stock on July 19, 2011.

The investigation seeks to determine whether Allos’ Board of Directors breached their fiduciary duties to Allos shareholders in connection with their efforts to sell Allos to AMAG at an inadequate price through an unfair process which significantly undervalues the Company.

If you are a current investor in Allos who purchased Allos shares before July 20, 2011, and you wish to discuss this investigation or have any questions concerning this notice or your rights or interests with respect to these matters, please contact Katherine E. Smith at (800) 497-8076 or (212) 682-1818, or by email at investigations@muarrayfrank.com.