He said he was deep asleep when he got the phone call from the Nobel committee at 3 a.m. local time. "He sounded very serious," Capecchi said, "so the first reaction was, `This must be real.'"
Smithies told The Associated Press getting award was "very gratifying." After working on the research for more than 20 years, he said it's "rather enjoyable being recognized at this level."
Smithies said he hopes winning the prize will make it easier to secure funding for other work.
Although gene targeting uses embryonic stem cells from mice, it is different from how stem cells would be used to treat disease in humans. In people, stem cells would be prodded to become replacement tissue like nerve cells for transplant into patients.
Capecchi's work has uncovered the roles of genes involved in organ development in mammals, the committee said. Evans has developed strains of gene-altered mice to study cystic fibrosis, and Smithies has created strains to study such conditions as high blood pressure and heart disease.
The medicine prize was the first of the six prestigious awards to be announced this year. The others are chemistry, physics, literature, peace and economics.
The prizes are handed out every year on Dec. 10, the anniversary of award founder Alfred Nobel's death in 1896.
Last year, the Nobel Prize in medicine went to Americans Andrew Z. Fire and Craig C. Mello for discovering RNA interference, a process that can silence specific genes.
