** FILE ** Japanese scientist Shinya Yamanaka (left) and British researcher John Gurdon, winners of the 2012 Nobel Prize in medicine, speak to each other at a symposium in Tokyo in April 2008. (AP Photo/Kyodo News)

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** FILE ** Japanese scientist Shinya Yamanaka (left) and British researcher John Gurdon, winners of the 2012 Nobel Prize in medicine, speak to each other at a symposium in Tokyo in April 2008. (AP Photo/Kyodo News)