Liver tissue (100 mg) was homogenized in 1 ml RIPA buffer (Thermo Fisher Scientific, Inc.) containing 10 µl phenylmethylsulfonyl fluoride, and centrifuged at 6,700 × g at 4°C for 5 min. The middle protein layer was taken to measure the protein concentration using a bicinchoninic acid kit (Bio-Rad Laboratories, Inc.). The samples were diluted to 50 µg/µl, mixed with sample buffer (4:1) and heated at 100°C for 5 min. SDS-PAGE (12%) was carried out and 10 µg of protein was loaded per lane and proteins were transferred onto a PVDF membrane. Membranes were blocked in TBS-0.05% Tween (TBST) containing 5% skim milk for 1 h at 25°C. After blocking, the membrane was incubated at 25°C for 2 h with primary antibodies against Cu/Zn-SOD (cat. no. PA5-270240; 1:1,000), Mn-SOD (cat. no. LF-MA0030; 1:1,000) and beta-actin (cat. no. MA5-15739; 1:1,000). The membrane was then washed with TBST and incubated at 25°C for 1 h with secondary antibody (cat. no. A32723; 1:500) (17 (link)). All antibodies were supplied by Thermo Fisher Scientific, Inc. SuperSignal™ West Pico Plus was used to visualize proteins by iBright FL1000 (both Thermo Fisher Scientific, Inc.). ImageJ version 1.44 (National Institutes of Health) was used for semi-quantitative analysis of protein expression.