(E, left and middle) Brightfield images of the indicated myotubes treated or not with 3-MA at DM-8. (right) Immunostaining for MHC (red) at DM-14 in the presence of 3-MA. Arrowheads label 3-MA-rescued Rb−/− myotubes at DM-8. 3-MA-rescued, twitching Rb−/− myotubes are shown in Video 4. 