To investigate the inhibitory effects of MIT on breast cancer cells, we treated 11 breast cell lines, including immortalized breast cell lines (HBL-100 and MCF10A), ER+ breast cancer cell lines (MCF7 and T47D), HER2+ breast cancer cell lines (SKBR-3 and BT474) and TNBC cell lines (HCC1937, HCC1806, SUM149PT, MDA-MB-231 and MDA-MB-468), with MIT and measured cell viability. The gene discussed is ERBB2; the disease is breast carcinoma.