File:Repressors modulate transcription output..jpg

English: A. Oct4, Nanog and Tcf3 co-occupy a common set of pluripotency-associated factors in ESCs. Whereas Oct4 and Nanog may activate genes required for pluripotency, Tcf3 behaves as a repressor that also binds these common genes, thereby controlling the overall gene expression levels. B. At the single gene level, the transcription output is partly determined by the combination of factors that activate or repress transcription. The well-characterized Oct4 gene cis-regulatory regulatory region is bound by several TFs that act as either activator or repressor. In the undifferentiated state, Oct4, Sox2, Nanog, Sall4 and LRH1 activate the promoter while Tcf3 and GCNF repress it. The balance of molecules acting on this critical gene controls the cell fate of either self-renewal or differentiation.