Adult stem cells lack key pluripotency regulator The protein Oct4 plays a major role in embryonic stem cells, acting as a master regulator of the genes that keep carefully the cells within an undifferentiated state. Unsurprisingly, experts learning adult stem cells have long suspected that Oct4 also is critical in enabling these cells to remain undifferentiated. Indeed, more than 50 studies have reported obtaining Oct4 activity in adult stem cells ed medications . But those results are misleading, according to research in the laboratory of Whitehead Member Rudolf Jaenisch. On October 10 In a paper released online in Cell Stem Cells, postdoctoral fellow Christopher Lengner shows that Oct4 is not required to maintain adult stem cells in their undifferentiated condition in mice, and that adult cells function normally in the absence of Oct4.