Stem cell rat race

In 1981, Martin Evans and Matthew Kaufman, working at the University of Cambridge, UK, and Gail Martin, working at the University of California, San Francisco, independently and simultaneously discovered methods to isolate mouse embryonic stem (ES) cells and grow them in culture. The hard part, they assumed, was over. "Everyone thought that within five minutes we'd have embryonic stem cells from everything," including the mouse's cousin, the rat, says Mia Buehr, a postdoc at the University of Edinburgh. But that achievement would take another 27 years.