Effects of ALA and EAAs on the DNA damage of C2C12 cells during proliferation. (A) Immunostaining images of the DNA damage marker, phosphorylated H2A.X variant histone (p-H2AX) (green), and the nuclear marker, Hoechst 33258 (blue), in C2C12 cells. All experiments were performed thrice and the representative result is shown. Scale bars represent 20 μm. (B) Quantification of colocalization of p-H2AX with Hoechst 33258 from random fields. Bar graph represents the mean ± SEM values from three independent experiments.