Master regulators play multiple roles in tissue specification. When tissue specification starts the transcriptomic network entails orchestration with certain genes activated, while others repressed. In these tightly-regulated processes, often one or two most essential transcriptional factors (known as master regulator) function to control all the downstream transcriptional machinery. Increasing evidence supported that master regulators are capable of governing the differentiation process via distinct mechanisms. They can be both activators and repressors, which is largely dependent on the identity of cofactors they cooperate with. This is well exemplified by MyoD in myogenesis, RUNX2 in osteoblast genesis and YY1 in early embryogenesis17,37,38.
