A previous study indicated that ER located near the cell membrane is able to activate many receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) and HER2/neu (HER2) [12], and it has been suggested that this might be a possible mechanism for the presence of tamoxifen resistance in ER(+)/HER2(+) breast cancers [13]. This evidence concerns the gene ERBB2 and breast cancer.