Fig. 7. TNFα-mediated caspase activation and inhibition of myoblast differentiation requires bax. (A) Photomicrographs of primary cultures from myogenic cells derived from wild-type (+/+), caspase-3- or Bax-deficient mice, cultured in DM in the absence or continuous presence of TNFα (+TNFα) and immunostained for myosin. Quantitative analysis of myogenic differentiation (% differentiation) reveals that while TNFα potently inhibits myogenic differentiation of both wild-type and caspase-3-deficient cells, it does not affect myogenic differentiation of Bax-deficient cells. (B) Caspase activation analysis (green) in wild-type (+/+) and Bax-deficient primary myoblasts. Nuclei were stained with Hoechst (blue). Bax-deficient cells are not responsive to TNFα in terms of caspase activity.