Americans Elizabeth H. Blackburn, Carol W. Greider and Jack W. Szostak won the 2009 Nobel Prize in medicine on Monday for discovering a key mechanism in the genetic operations of cells, an insight that has inspired new lines of research into cancer. It was the first time two women have been among the winners of the medicine prize. The trio solved the mystery of how chromosomes, the rod-like structures that carry DNA, protect themselves from degrading when cells divide. The Nobel citation said the laureates found the solution in the ends of the chromosomes -- features called telomeres that are often compared to the plastic tips at the end of shoe laces that keep those laces from unraveling.
