This year's Nobel Prize in Medicine goes to John B. Gurdon of Britain and Shinya Yamanaka of Japan "for the discovery that mature cells can be reprogrammed to become pluripotent."

The award honors Gurdon's classical experiment in 1962, showing that developmental biology was possible using the nucleus of an adult cell. Gurdon had taken a fertilized frog's egg and removed the nucleus before the egg began to divide into many cells. He then inserted the nucleus from a frog's intestinal cell and the egg continued to divide and develop into a tadpole and adult frog. With that knowledge scientists later began cloning animals around the world.

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In 2006, Yamanaka showed that coaxing adult cells into behaving with pluripotent power, the ability to develop into any body part could be finessed. Why make a baby frog if you only want frog's legs? But in this case Yamanaka used mice. Earlier work by Martin Evans had shown that stem cells isolated from a mouse embryo could be cultured in the laboratory. Yamanaka identified dozens of genes that could potentially be responsible for keeping these stem cells immature and pluripotent. He then tested several different combinations of these genes on adult cells from connective tissue, called fibroblasts, to see what would happen.

Yamanaka and his team discovered they needed only four genes to reprogram the adult cells into behaving like stem cells. These induced pluripotent stem cells (IPS) revolutionized the field of genetic engineering.

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IMAGES: Video screen grabs from the video announcement of the 2012 Nobel Prize in Physiology or Medicine.