ACTA1 and myopathy: Finally, compared to controls and the ACTA1 samples, we observed almost no MYH1 (using the monoclonal antibody MF-20) reactivity in GNE1 and reduced expression in GNE2 (Fig. 3d and Supplementary Fig. 2B), suggesting that myogenic differentiation is impaired in GNE myopathy iPSCs, but importantly is not the case in all myopathy-derived iPSCs, progressing down a skeletal muscle lineage.