The cytotoxic effect of CCA-1.1 was investigated in various breast cancer cell lines (MCF-7/HER2, 4T1, MCF-7, HCC1954, T47D), human leukemic cells (K562), human colon carcinoma cells (Caco2 & WiDr), and immortalized fibroblast cells (NIH-3T3). This evidence concerns the gene ERBB2 and breast carcinoma.