NRK-49F cells were transfected with scrambled siRNA or siRNAs specific to HDAC1 and HDAC2, respectively and then incubated for 48 h in DMEM with 5% FBS. Cells were harvested and cell lysates were subjected to immunoblot analysis with antibodies to cyclin D1, p27, p57 or GAPDH. Representative immunoblots from 3 or more experiments are shown (A). Expression levels of cyclin D1, p27 and p57 in different groups were quantified by densitometry and normalized with GAPDH (B, C) Data are expressed as means ± S.D. Bars with * are significantly different from controls (p<0.05).