On April 13, 2018, George Golumbeski, notified Acceleron Pharma Inc. of his decision to resign from the Company's Board of Directors effective as of the company's Annual Meeting of Stockholders on June 6, 2018. Dr. Golumbeski has served on the Board since 2011, and his resignation from the Board will be effective subsequent to his retirement from Celgene Corporation. The resignation of Dr. Golumbeski was not caused by any disagreement with the Company.