Effect of apigenin and HDAC inhibitor TSA on the expression of class I HDACs in human prostate cancer cells. A, Inhibition of HDAC1 and HDAC3 protein expression at 20 μM and 40 μM doses of apigenin and 20 ng/ml HDAC inhibitor TSA for 24 h Panel 1, PC-3 cells and Panel 2, 22Rv1 cells. B, Inhibition of mRNA levels of HDAC1 and HDAC3 at 20 μM and 40 μM doses of apigenin and 20 ng/ml HDAC inhibitor TSA for 24 h Panel 1, PC-3 cells and Panel 2, 22Rv1 cells. Data represents the mean ± SD of three different assays. *P <0.05, and **P <0.001 versus control. The details are provided in ‘materials and methods’.