To determine the involvement of apoptosis in the Cu(sal)(phen) activity, all breast cancer cell lines MCF-7, T47D, MDA-MB-231 and BT-20 were treated with 5, 10 and 25 μM of Cu(sal)(phen) for 24 hrs, and then apoptosis was analyzed by flow cytometry after Annexin V/PI double staining. This evidence concerns the gene ANXA5 and breast carcinoma.