JC-1 staining assay further suggested that ursolic acid (1~30 μM) could induce mitochondrial depolarization and apoptosis of breast cancer cells (Figure 2E), which was achieved by attenuating the anti-apoptotic protein Bcl2 whereas elevating the pro-apoptotic proteins Bax and cleaved PARP (Figure 2F and Supplementary Figure 3). Here, BAX is linked to breast cancer.