Due to less efficiency in formation of xenograft tumors in nude mice using the AU565 cell line, and extremely fast growth rate of the mouse breast cancer cell line EMT-6 in xenograft, we switched to a very commonly used ovarian cancer cell line SKOV-3 with a high HER2 expression and a breast cancer cell line MDA-MB-231 with low expression level of HER2. This evidence concerns the gene ERBB2 and breast cancer.