Oct4 (Octamer binding transcription factor 4) is an important marker of the undifferentiated state and a central regulator of pluripotency in ES cells. When embryonic stem cells are triggered to differentiate, Oct-4 is downregulated thus providing a model for the early events linked to somatic differentiation in the developing embryo. Oct4 is nucleus protein, with a predicted molecular weight 39 kD. The poly6318 antibody recognizes human Oct4 and has been shown to be useful for immunofluorescent staining.