Given the striking inability of GNE1 iPSCs to form mature skeletal muscle myotubes, we next sought to query stage-specific myogenic regulatory factor (MRF) protein expression in differentiating control, GNEM, and nemaline myopathy iPSCs (hereby referred to as induced myogenic progenitor cells, or iMPCs). The gene discussed is MYRF; the disease is nemaline myopathy.