CASP3 and breast cancer: We have previously shown that most breast cancer cell lines were resistant to TRAIL, and chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide and camptothecin) or irradiation sensitized TRAIL-resistant cells to undergo apoptosis through upregulation of death receptor DR4 and/or DR5 and activation of caspase-3 [12,30].