Notable losers in May included BioTime, a regenerative medicine firm run by Michael West, who was one of the key figures in the early days of embryonic stem cell research, and Cytori Therapeutics, which is trying to commercialize stem cells found in fat for breast reconstruction and other uses.

FORBES: Biotech Busts And Breakthroughs In May

Obama's order directs the NIH to develop revised guidelines on federal funding for embryonic stem cell research within 120 days, according to Dr. Harold Varmus, president of Memorial Sloan-Kettering Cancer Center and co-chairman of Obama's science advisory council.

CNN: Obama overturns Bush policy on stem cells

After several days, the ball of cells that results contains a blanket of embryonic stem cells endowed with the genetic material of the donor skin cell, which have the ability to generate every cell type from that donor.

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Instead of generating embryonic stem cell lines via nuclear transfer, Hwang's group produced the stem cells from days-old embryos, a technique that had already been established by James Thomson at University of Wisconsin in 1998.

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And what they found was that after a few days, these genes that they added were able to get the skin cells to start behaving just like embryonic stem cells.

NPR: Scientists Create Embryonic Stem Cells from Skin