Myogenin is a member of a family of myogenic regulatory genes, which includes MyoD, myf5 and MRF4. These genes encod e a set of transcription factors, which are essential for muscle development. Transfection of myogenin in to multipotential mesodermal cells have been shown to convert the mesodermal cells to myoblasts. Expression of myogenin is restricted to cells of skeletal muscle origin. It is therefore a useful marker for tumors of the muscle lineage, being strongly expressed in alveolar rhabdomyosarcomas.