The 2007 Nobel Prize in Medicine or Physiology shared by three researchers, Mario Capecchi, Martin Evans and Oliver Smithies for their studies of embryonic stem cells in mice.

The 2007 Nobel Prize in Physiology or medicine goes to Mario Capecchi, Martin Evans and Oliver Smithies for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells," said Professor Christer Betsholtz of the Karolinska Institute, announcing the winners of perhaps the most prestigious award in medicine.

Mario Capecchi, orphaned during World War II in his native Italy, made his way to the United States and earned a doctorate from Harvard University in 1967. He is currently Distinguished Professor of Human Genetics and Biology at the University of Utah and a member of the National Academy of Sciences. Oliver Smithies is a British-born American holding the post of Excellence Professor of Pathology and Laboratory Medicine at the University of North Carolina at Chapel Hill. Capecchi and Smithies studied the process by which natural selection increases genetic variation in a population by exchange of DNA sequences.

Working together, they set out to prove that this homologous recombination could be used to specifically modify genes in mammalian cells. Their process came to be known as gene targeting.  By 1986, the two began working with Sir Martin J. Evans, 66, of Cardiff University in Wales. Dr. Martin Evans a Fellow of the Royal Academy, provided the cellular vehicle that Capecchi and Smithies needed by showing that mouse embryonic stem cells would pass on introduced genetic modifications. Capecchi, Smithies and Evans will share an award of more than $1 million, and they will be invited to Stockholm this December to receive their gold Nobel medallions from Sweden's King Carl XVI Gustaf.