PTS2 induces cell cycle arrest in cancer cells. (A) Cancer cells were incubated with PTS2 (2.5 μg/ml) for 24 h, harvested and stained with propidium iodide (PI). Nuclei fluorescence was measured. Percentages of cells in each cell cycle phase are also shown. Results are representative of 3 independent experiments. (B) Cells were incubated with PTS2 (2.5 μg/ml) for 24 h, and then harvested. Western blot was performed using antibodies to p53, p21, CyclinD1, CyclinE1 and GAPDH. Results represent three independent experiments.