p43 regulates myoblasts proliferation. (A) Time needed to reach 80% of confluence in p43−/−, p43-Tg and WT primary myoblasts. (B) Proliferation rate monitored at 34 hours attested by relative DNA concentration in p43−/−, p43-Tg and WT primary myoblasts using Quantifluor (n = 5 for each group). (C) Cytoimmunofluorescence studies using antibodies raised against Troponin T were performed on WT, p43−/− and p43-Tg myoblats after 3 days in differentiation medium. (D) To assess the extent of differentiation, the fusion index (percentage of nuclei incorporated into myotubes relative to the total number of nuclei) was calculated. (E) Myogenin and total MyHC protein levels were analysed by Western blot (n = 6 for each group). Typical blots are shown. Proteins were quantified with Image Lab™ Touch Software. Statistical significance: *p < 0.05. Student’s t-test. Results are expressed as ± sem.