Cell culture
Mouse fibroblast-derived 3T3-L1 preadipocytes and C2C12 mouse skeletal muscle cells were purchased from American Type Culture Collection (ATCC, Manassas, VA, USA). 3T3-L1 was cultured in DMEM (WELGENE, Daegu, Korea) containing 10% bovine calf serum (BCS, WELGENE, Daegu, Korea) and 100 unit/ml penicillin/streptomycin (P/S, WELGENE, Daegu, Korea) at 37°C, below 5% CO2. C2C12 was cultured in DMEM with 10% fatal bovine serum (FBS) and 100 unit/ml P/S at 37°C, below 5% CO2.