Tks5 undergoes isoform switch during myoblast differentiation. (A) Domain structure of different Tks5 isoforms. Red box represents exon 6β, which is unique in Tks5β. (B–D) The expression of Tks5 isoforms during myogenesis. Expression of protein or mRNA levels of different Tks5 isoforms in myoblasts upon differentiation were examined with immunoblotting (B and C) or quantitative PCR (D). C was derived from the results using anti-SH3 antibody. (E) Promoter activity of Tks5α promoter upon myoblast differentiation. Dual luciferase reporter assay of Tks5α promoter was performed and compared among day 0 or 3 differentiated C2C12. The MyoG E-box serves as positive control. (F) Dual luciferase reporter assay of different E-box mutations of Tks5α promoter. Data were analyzed with one-way ANOVA (C, D, and F) or Student’s t test (E). *, P < 0.05; **, P < 0.01; ***, P < 0.001.