Representative Western blots (a) of the protein content of SOD2 (b), GPx1 (d), catalase (e), 4-HNE (f), COX2 (g) and p65 (h), and SOD2 enzyme activity (c) in two skeletal muscles and cardiac muscle of young (N = 8), mid-aged (N = 8), and old mouse (N = 8), respectively. Data are mean ± SEM. *P < 0.05, **P < 0.01, Mid-aged or Old vs. Young; †P < 0.05, ††P < 0.01, old vs. mid-aged