Apoptotic induction by cucurbitacin B. MCF-7 and MDA-MB-231 were incubated with cucurbitacin B for 24 hr and apoptosis was analyzed by Annexin V-FITC. A. Annexin V-FITC staining is represented on the X-axis and PI staining is represented on the Y-axis. B. The values indicate the percentage of apoptotic cells in each concentration. Results shown are the average of three independent experiments. *, p<0.05 (treated vs untreated control).