Stem Cells Portal, 25 Nov 2011 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0027520
Stem Cells Portal, 18 Nov 2011 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0027520