Figure 3: Cell death of breast cancer cells induced by cucurbitacin B. MCF7:5C, MDA-MB-231, and SKBR-3 were incubated with cucurbitacin B for 48 hr and apoptosis was analyzed by staining phosphatidylserine translocation with FITC-Annexin V. Annexin V staining is represented on the 𝑥 -axis and PI staining is represented on the 𝑦 -axis (a). The most representative result of three independent experiments is shown. Simple vertical bars represent the mean apoptosis rate of all of breast cancer cells (b). Results shown are the average of three independent experiments. 𝑃 < 0 . 0 5 versus nontreated control, 𝑃 < 0 . 0 1 versus nontreated control.