(A) HCT116 and MCF-7 cells were incubated under CR conditions for the indicated time. (B and C) Cells were transfected with CK2α siRNA for 1.5 days, then incubated under CR conditions for 7 h. The levels of each protein (A and B) and mRNA (C) were then determined by immunoblotting using specific antibodies, and by RT-PCR analysis using specific primers, respectively (top). Representative data from three independent experiments are shown. β-Actin was used as a control. The graphs represent the quantitation of CK2α, CK2β, and SIRT1 relative to β-actin, and p-AMPK (T172) relative to the unphosphorylated AMPK (bottom). Data were reported as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001. Bars that do not have the same letter (a, b, c) were significantly different among groups at P < 0.05.