Effect of dietary lycopene supplementation on AMP-activated protein kinase (AMPK) signaling pathway in longissimus dorsi (LD) muscle of finishing pigs. (A) The protein expressions of AMP-activated protein kinase (AMPK) and phospho-AMP-activated protein kinase (p-AMPK). (B) The protein expressions of nuclear respiratory factor 1 (NRF1), calcium/calmodulin-dependent protein kinase β (CaMKKβ), sirtuin1 (Sirt1) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). (C) The mRNA expressions of AMP-activated protein kinase α1 (AMPKα1), AMP-activated protein kinase α2 (AMPKα2), sirtuin1 (Sirt1) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). Data are presented as the mean and SEM (n = 6). a, b, c Bar with different letter indicates significant difference (P < 0.05).