Cultured NRK-49F cells were transfected with specific siRNA for AMPKα1 (10 nM, 100 nM) or AMPKα2 (10 nM, 100 nM) or a control siRNA for 24 h. After 24 h of incubation, transfected cells were pre-incubated with or without AICAR (0.5 mM) for 30 mins. Then, these cells were stimulated with TGF-β1 (1 ng/mL) for 24 h before harvesting. (A) The inhibitory effects of siAMPKα1 were evaluated by measuring phospho-AMPKα and total-AMPKα levels. Representative immunoblots from three independent experiments are shown. (B) The efficiency of different concentrations of siAMPKα1 (1 nM, 10 nM, 50 nM, 100 nM) on AMPKα1 mRNA expression were evaluated. Data are expressed relative to the expression in control cells without transfection. Each bar represents the mean ± S.E. of three independent experiments. *P<0.05 versus the TGF-β1 group; #P<0.05 versus the TGF-β1+ AICAR group; ##P<0.05 versus the control group. C: control, T: TGF-β1, A: AICAR.