Molecular mechanistic understanding has revealed that IGFBP1 is a key component of G protein-coupled estrogen receptor 1 (encoded by GPER1) which regulated the sensitivity of breast cancer cells to tamoxifen [46,47], and the resistance induced by RG7388 (MDM2 inhibitor) in glioblastoma [48]. This evidence concerns the gene GPER1 and breast carcinoma.