Nobel prize-winner Edwin Krebs died from progressive heart failure. He was 91. Krebs shared the 1992 Nobel prize in physiology or medicine with Edmond Fischer for their elucidation of the regulatory role of reversible protein phosphorylation. "It was an embarrassingly simple reaction that we found," Fischer told the New York Times. While the importance of their discovery took a while to catch on, Fischer says that "these days there's not a pharmaceutical house or biotech company that doesn't have an eye on those reactions."