CASP3 and breast cancer: However, treatment with 20 μM γ-tocotrienol, a dose previously shown to induce apoptosis in mammary cancer cells [13, 14] and used as an apoptosis-inducing positive control in this experiments was found to induce a large increase in cleaved PARP and cleaved caspase-3 levels, and corresponding decrease in viable cell number in both MCF-7 and MDA-MB-231 breast cancer cells 24 h following treatment exposure (Figures 11(a) and 11(b)).