(A) Mean number of myotubes per field in indicated myoblast cultures induced to differentiate after transduction with Ad.GFP or Ad.Bcl-2. Each point represents the mean ± SD of six fields from six independent experiments. Bcl-2-rescued, twitching Rb−/− myotubes are shown in Video 2. (inset) Western blot for Bcl-2 in Ad.Bcl2-transduced versus uninfected primary myoblasts. 