The pluripotency regulator Oct4: a role in somatic stem cells?

Since its discovery as a critical regulator of pluripotency in embryonic stem (ES) cells and the inner cells mass of the developing blastocyst, the Pou domain-containing transcription factor Oct4 has become a proxy for "stemness" in numerous studies of somatic stem cells as its presence is often taken as evidence of pluripotency in these cells. Recent studies, however, have demonstrated that not only is Oct4 dispensable for maintaining potency in somatic stem cell compartments, but also that the methods applied to detect Oct4 and the interpretation of the resulting data may be flawed. Here we contrast pathways known to govern pluripotency in embryonic stem cells with those in adult stem cells and critically discuss the concept of pluripotency in adult stem cells of the mammalian soma.