CASP3 and breast cancer: However, treatment with 20 μM γ-tocotrienol, a dose previously shown to induce apoptosis in mammary cancer cells [2] and used as a positive control in this study, was found to induce a large increase in cleaved PARP and cleaved caspase-3 levels and decrease viable cell number in +SA cells (Figures 12(a) and 12(b)).