Induction of apoptosis by reversine. (A) OSCC cells were treated with DMSO or different concentrations of reversine (5 and 10 μM). At indicated time points (12, 24 and 48 h), cells were dually stained with annexin V-FITC and PI as described and analyzed by flow cytometry. The percentage of cells in early apoptosis and early apoptosis plus late apoptosis of OC2 and OCSL cells were evaluated, respectively. All results were obtained from three independent experiments. * indicated significant difference from the untreated cells (DMSO) (p < 0.05). (B) The representative figure of flow cytometry from OCSL cells treated as described in (A). (C) OSCC cells harvested from (A) were used to analyze the expression of apoptosis-related proteins. Cells treated with 50 μM etoposide to induce apoptosis were used as a positive control.