Mario Ramberg Capecchi is an Italian-born American molecular geneticist and a co-winner of the 2007 Nobel Prize in Physiology or Medicine for discovering a method to create mice in which a specific gene is turned off, known as knockout mice.  MARIO R. CAPECCHI was born in Verona, Italy in 1937. He received his B.S. degree in chemistry and physics from Antioch College in 1961 and his Ph.D. degree in biophysics from Harvard University in 1967. In the 1980s Capecchi began his prize-winning research, which helped give rise to gene targeting. He developed a technique using recombinant DNA technology whereby DNA could be injected into the nucleus of mammalian cells, greatly enhancing the effectiveness of gene transfer. He further refined his procedure, incorporating the work of Evans and Smithies into his research, and the cooperative effort gave rise to the “knockout mouse” a laboratory mouse in which one or more genes had been selectively inactivated or “knocked out.”