Mario Renato Capecchi ( born 6 October 1937 ) is an Italian-born American molecular geneticist . He won the 2007 Nobel Prize in Physiology or Medicine with Sir Martin Evans and Oliver Smithies . Mario Renato Capecchi ( Verona , Italy , 6 October 1937 ) is an Italian-born American molecular geneticist and a co-winner of the 2007 Nobel Prize in Physiology or Medicine for discovering a method for introducing homologous recombination in mice employing embryonic stem cells , with Martin Evans and Oliver Smithies .