BBC: John Gurdon of Cambridge University in the UK and Shinya Yamanaka of Kyoto University in Japan will share this year’s Nobel Prize in Physiology or Medicine, the Royal Swedish Academy of Sciences announced today. Gurdon’s and Yamanaka’s research revealed that, contrary to prevailing wisdom, a cell’s type is not fixed forever once the cell is mature. Rather, with judicious manipulation, mature cells can recover their youthful ability to develop into other types. Gurdon made the first important step toward that realization when, in 1962, he replaced the immature cell nucleus in a frog egg cell with the nucleus from a mature intestinal cell. A normal tadpole developed from the modified egg, demonstrating that the mature cell’s DNA retained the information needed for building all a frog’s cells. In 2006 Yamanaka discovered that he could turn mature mouse cells into immature stem cells simply by inserting a few additional genes. The modified stem cells are pluripotent—that is, they can develop into any other type of cell. The ability to reprogram mature cells could not only revolutionize the diagnosis and treatment of human diseases but also circumvent ethical objections to using stem cells extracted from human embryos.