SLC39A7 and breast carcinoma: Interestingly, our tamoxifen-resistant MCF-7 derived breast cancer model (TamR) has both a higher level of available zinc8 and an increased gene expression of zinc transporter ZIP7.31 Removal of ZIP7 from TamR cells confirmed its role in activating epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor (IGF-1R),8 both of which are known to drive the growth of these TamR cells.32