Shinya Yamanaka from Kyoto University was named the winner of the Nobel Prize in Physiology or Medicine for discovering how mature, adult cells can be reprogrammed into immature stem cells. Shizuo Kambayashi/Associated Press hide caption

itoggle caption Shizuo Kambayashi/Associated Press

Dr. Ralph Steinman of Rockefeller University died Friday, three days before he was named a winner of the Nobel Prize in Physiology or Medicine for "his discovery of the dendritic cell and its role in adaptive immunity."

Mike Groll/AP hide caption

itoggle caption Mike Groll/AP