The Effect of YQFS on apoptosis and the cell cycle in HCT-116 cells. (A) Flow cytometry analysis of the cell cycle distribution of cultured HCT-116 cells with PI staining following 24 h exposure of cells to YQFS. Detection of apoptosis with Annexin V-FITC/PI binding to HCT-116 cells. Viable cells (Annexin V−/PI−) are located in the lower left, apoptotic cells (Annexin V+/PI−) in the lower right, post apoptotic secondary necrotic cells (Annexin V+/PI+) in the upper right and primary necrotic cells (Annexin V−/PI+) in the upper left quadrants, respectively. The numbers in each quadrant are the percentages of cells in question. (B) Distribution of HCT-116 cells’ cycle indicated by PI staining. The values shown are the mean ± SEM of 3 experiments. **P < 0.01 vs. the control.