Yoshinori Ohsumi, a professor at the Tokyo Institute of Technology, smiles as he speaks with Japanese Prime Minister Shinzo Abe on a phone during a press conference in Tokyo today, after he was awarded the Nobel Medicine Prize. Toru Yamanaka/AFP/Getty Images hide caption

Emmanuel Kwame, who lost his sight to river blindness, in his cashew grove. Jason Beaubien/NPR hide caption

Satoshi Omura, Youyou Tu and William C. Campbell share in the 2015 Nobel Prize in Physiology or Medicine. Nobel Prize Committee hide caption

A screen presents the winners of the Nobel Prize in Medicine, U.S.-British scientist John O'Keefe and Norwegian husband and wife Edvard Moser and May-Britt Moser, for their discoveries of cells that constitute a positioning system in the brain. TT News Agency/Reuters/Landov hide caption

Molecular biologist Randy Sheckman, who shared the 2013 Nobel Prize in physiology or medicine, acknowledges applause after receiving his prize during the ceremony in Stockholm last December. Pascal Le Segretain/Getty Images hide caption

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

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."