Regarding GPR30-mediated signaling, its involvements mainly in cell-growth stimulation had been studied in various estrogen-related cancers since Filardo et al. [214] first described the estrogen-mediated and GPR30-dependent activation of MAP kinase Erk1/2 via transactivation of epidermal growth factor receptor in breast cancer cells. Here, GPER1 is linked to breast carcinoma.