Fig. 3.
Effect of DHFR knockdown on the expression of CDK2, CDK4, CDK6, cyclins D1 and E. At 72 h post-transfection with siRNA, cells were lysed with RIPA lysis buffer, and the lysates were then analyzed by western blot with specific antibodies (dilution 1:800). β-actin served as internal loading control (dilution 1:8,000). (A) Representative gels from 3 experiments are shown as protein expression levels of cyclin-dependent kinases CDK2, CDK4 and CDK6, as well as cyclins D1 and E. (B) Densitometric analysis was performed for each protein band relative to β-actin in the same sample using Image LabTM software. To compare the relative quantity (RQ) of proteins between NC-siRNA and DHFR-siRNA groups, the values of density ratio in NC-siRNA group were normalized to 1.00. *vs NC-siRNA, p<0.05; **vs NC-siRNA, p<0.01.