Fig. 6. Ectopic Pax7 perturbs differentiation in Pax7-null myogenic cells. YMCA cells infected with pMSCV-IRES-eGFP while proliferating and then stimulated to differentiate, readily fused into large multi-nucleated myotubes (a). When stimulated to differentiate however, pMSCV-Pax7-IRES-eGFP infected cells either remained single or fused into aberrantly shaped myotubes (b). As expected of a differentiated myogenic culture, most cells were refractory to BrdU incorporation when infected with control pMSCV-IRES-eGFP (c) whereas many cells infected with pMSCV-Pax7-IRES-eGFP continued to divide (d). Bar, 30 µm.