Yousefi et al. has shown that the inhibitory effect of silibinin on metabolic activity of metastatic human breast cancer cell line, SKBR3 (ErbB2-overexpressed and ER-negative breast carcinoma cell line) by MTT assay is concentrations and time intervals (24, 48 and 72 h) dependent (31). This evidence concerns the gene ERBB2 and breast cancer.