Relationships between MyoD and Rb1 in myogenesis.

Differentiation of skeletal myoblasts to multinucleated myotubes requires withdrawal from the cell cycle and is associated with the expression of muscle-specific gene products, such as MyoD, Myogenin, MRF4 and Myf-5. Several lines of evidence indicate that the function of Rb1 is invloved in the control of differentiation in certain tissues. Here, we report two types of regulatory interactions between MyoD and Rb1: 1) the function of the Rb1 gene product is required for MyoD mediated transcriptional activation of muscle specific genes. 2) MyoD induces high levelsof Rb1 gene transcription in differentiating myogenic cells.