CASP3 and breast cancer: Many anticancer drugs function by inducing apoptosis.1,2 Paclitaxel induces apoptosis in different cancer cells, including breast cancer,23 gastric cancer,43 colon cancer,44 and leukemia cells45 by modifying mitochondrial transition permeability, activating caspase-8 and caspase-3,44,46 and Bcl-2 inactivation by a mechanism that may involve the binding of paclitaxel to this antiapoptotic protein.47 As demonstrated in this study, heat-killed baker’s yeast also acts as an anticancer agent via induction of apoptosis.