Pluripotency without tumors?

Japanese researchers who linkurl:reprogrammed;http://www.the-scientist.com/blog/display/53873/ pluripotency into adult human skin cells say they have improved the technique, according to a linkurl:paper;http://www.nature.com/nbt published online today (Nov. 30) in Nature Biotechnology. linkurl:Shinya Yamanaka;http://www.frontier.kyoto-u.ac.jp/rc02/kyojuE.html of Kyoto University and his colleagues originally used four transcription factors to induce pluripotency in linkurl:mouse;http://www.the-scientist.com/blog/display/24307/ embryonic and adult fibroblast cells, and most recently, linkurl:adult human skin cells.;http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=18035408&ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum But the process caused tumors in a significant percentage of the chimeric mice generated from the cells - a problem the researchers attributed to one of the four genes, c-Myc, which induces proliferation. In the current study, the researchers showed that pluripotent cells can be made from both mouse and human adult cells without introducing the c-Myc gene, by transducing just the other three. It's not that Myc isn't needed in the process, the authors noted in the paper; rather, they suggest that the other three genes may be spurring endogenous...