ERBB2 and breast carcinoma: For high HER2 expressing cells: AU565 (breast carcinoma), SKBR-3 (breast carcinoma), and SKOV3 (ovarian carcinoma) the EC50 was between 10−10 and 10−11 M. This shows that the toxins are extremely potent on cells with high HER2 expression derived from epithelial tissues of different origin.