Previously, we showed that 4-hydroxytamoxifen (Tam) induces the expression of insulin-like growth factor-binding protein 1 (IGFBP1) via a GPER1-dependent mechanism in MCF-7 and SkBr-3 breast cancer cells (Vaziri-Gohar & Houston 2016). Here, IGFBP1 is linked to breast carcinoma.