{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"MyoD belongs to a family of proteins known as myogenic regulatory factors (MRFs) and has a key role in regulating muscle differentiation. These bHLH (basic helix loop helix) transcription factors act sequentially in myogenic differentiation. MyoD is expressed in activated satellite cells, but not in quiescent satellite cells. In development, MyoD commits mesoderm cells to a skeletal lineage, and then regulates that process. It may also play a role in muscle repair. In abnormal tissues, MyoD1 labels tumor cells in Rhabdomyosarcoma and is one of the earliest markers of myogenic commitment."}]}]}