Cell culture materials Medium 254, Medium 254 supplement, fetal bovine serum (FBS), Dulbecco’s modified Eagle medium (DMEM), and antibiotics were obtained from Gibco (Waltham, MA, USA). Short interfering RNA (siRNA) transfection reagent, Trizol reagent, 1-bromo-3-chloropropane (BCP), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma Chemical (St. Louis, MO, USA). ToolScript MMLV RT kit and TOOLS 2× SYBR quantitative real-time polymerase chain reaction (qPCR) Mix was purchased from Biotools (Taipei, Taiwan).