Figure 5. CDK4/6 inhibitors lower the proportion of Phosphorylated-pRB and the total amount of pRB proteins in SW-13 cells. (a and b) total pRB protein, phosphorylated-RB (phospho-RB), CDK6 and CDK4 were detected by western blot. (a) The results present the relative amounts of either Phospho-RB or pRB in drug-treated cells, compared to Phospho-RB or pRB in mock-treated cells. Values are the mean and standard deviations of two independent experiments. For the western blot experiments, α-tubulin was used as a loading control. In (b), significance was tested with the t-test. *P<0.05, **P<0.01, ***P<0.001.