Myogenic markers and in vitro differentiation. (A) Reverse transcriptase PCR comparing primary (P) and immortalized (Im.) cell lines (control, oculopharyngeal muscular dystrophy (OPMD), Duchenne muscular dystrophy (DMD)) for myogenic markers (MyoD, N-CAM and desmin). Fibroblasts were used as a negative control. (B) Immunofluorescence was carried out using MF20, an antibody directed against sarcomeric myosin (green) after 5 days of differentiation. Specific antibody labeling was visualized using Alexa Fluor 488 secondary antibody (green). Nuclei were visualized with Hoechst (blue). Original magnification × 100.