Cellular Biology: Stem Winder

Since then, Thomson, an intensely private person, has been lofted out of obscurity. He received a red-carpet invitation to the Wisconsin state capital from then Governor Tommy Thompson, now Bush's Secretary of Health and Human Services. He is still consulted by Thompson's office on stem-cell issues but wasn't contacted directly by the White House for last week's decision. (Ironically, Thomson is the lead plaintiff in a case titled Thomson v. Thompson, seeking to force NIH to underwrite stem-cell research.)

Last year Thomson testified before the U.S. Senate on the value of stem-cell research. ("Scared me to death," he says.) So far, he has sold embryonic stem cells (at $5,000 for two vials) to some 30 research groups. Though he believes stem cells may someday be used to replace the faulty cells at the root of diseases like Parkinson's, he sees a more fundamental and perhaps more important role for them: explaining why some cells grow up healthy while others get sick and die. "We are simply ignorant about very early development," he says.

What's next for Thomson? Apart from possibly applying for that federal cash the President has promised, it's "to get back to work" and, he adds wistfully, "to obscurity." No chance of that.

--With reporting by Dick Thompson/Washington

For an animated graphic of embryonic stem-cell research, go to time.com/americasbest.com