Figure 4. Flow cytometry demonstrated the stages of cell apoptosis in human retinoblastoma (Y79) cells at different time points and for different concentrations of gossypol. Panels A and B show the percentages of different apoptotic stages in cells incubated with different concentrations of gossypol for 12 and 24 h. Data are presented as the mean±SEM. One-way ANOVA with a Bonferroni multiple comparison was used for statistical analysis. * p<0.05, compared to the control group. # p<0.05, compared to the 12-h group at the same dose. Images (C) and (D) show the distribution of cells in different apoptotic stages with gossypol treatment for (C) 12 h and (D) 24 h, by collecting the annexin V signals as FL1 and propidium iodide (PI) signals as FL3. n=6 in each group. Q3 shows the normal cell population; Q4 presents the early apoptosis stage and Q2 the late apoptosis stage.