Kevin Eggan, 31

While earning his PhD, Kevin Eggan helped make Rudolf Jaenischs lab at the Whitehead Institute for Biomedical Research a preeminent cloning lab. Eggan became "arguably the most skillful mouse cloner in this country," says Jaenisch. Eggan used those skills to clone mice from neurons, proving that animals could be cloned from even the most specialized cells in the body -- a feat that many scientists considered impossible. Eggan also helped explain how cloning "reprograms" the genetic material from an adult mouse cell, identifying the changes that take place to reset the nucleus to the beginning of development.

Eggan, now an assistant professor of molecular and cellular biology, plans to create human stem cell lines from patients with neurodegenerative disorders such as Parkinsons and Lou Gehrigs diseases, in order to study disease development and search for new drugs. He has also begun studying nuclear reprogramming in human cells in the hope of finding a way to create patient-specific embryonic stem cells without using human eggs.