Protein analyses using specific ACTC and ACTA1 antibodies. (A) Western blotting: Coomassie blue staining shows equal loading for myosin (∼220 kD) for all mouse quadriceps protein samples (lanes 1 and 2 = wild-type CBA/Ca;C57BL/6, lanes 3–5 = ACTC^Cr, lanes 6–9 = ACTC^Co, lanes 10–13 = ACTC^Co/KO, and lanes 14–16 = wild-type FVB/n;CBA/Ca;C57BL/6). Western blotting was performed using antibodies against total actin (all six actin isoforms; 42 kD), the striated actin isoforms only (both ACTC and ACTA1), ACTC only, or ACTA1 only. (B) Immunostaining of soleus muscles from 3-mo-old male ACTC^Co/KO and wild-type mice using anti-ACTC (red fluorescence) and anti-ACTA1 (green fluorescence) antibodies. The arrow indicates a muscle spindle positive for ACTC. Quadriceps, gastrocnemius, and EDL muscles were also examined and showed similar results (not depicted). (C) Representative flow cytometry of myofibers dissociated from the quadriceps muscles of 9-mo-old male wild-type and ACTC^Co/KO mice and stained using anti-ACTC and anti-ACTA1 antibodies (n = 12). Gastrocnemius, soleus, and EDL muscles were also examined and showed similar results (not depicted). Bar, 50 µm.