The IC50 value was less than 8 μM in MCF-7 cells and less than 20 μM in MX-1 cells.Peptide exhibited relatively higher cytotoxicity against breast cancer cells than against normal cells (IC50 > 60 μM).Significant apoptotic activity was detected by annexin V-FITC/PI staining. This evidence concerns the gene ANXA5 and breast cancer.