Figure 4

Effect of FTY720 on cell cycle proteins and cell cycle progression. (A) FTY720 induces expression of p16 and p27 and reduces expression of cyclin D1, CDK4, cyclin E and CDK2. CC cells were treated with FTY720 at the indicated concentrations for 24 h. Lysates were then prepared immediately and analyzed by western blotting for cyclin D1, CDK4, cyclin E, CDK2, p16 and p27. β-Actin was used as the internal control. All assays were done in triplicate. (B) Cell cycle analysis of FTY720-treated CC cells showing arrest in G1 phase. CC cells were incubated with FTY720 for 24 h. The percentage of cells in each phase of the cell cycle is presented as the mean ± SD from three independent experiments. Following treatment with FTY720 for 24 h, there was a significant increase in the percentage of cells in G0/G1 relative to the control group. (C) A representative example of cell cycle arrest in QBC939 cells treated with FTY720 for 24 h.