Our studies and others have also demonstrated that GPR30 mediates the rapid response to E2 in a variety of estrogen-responsive cancer cells by activating the epidermal growth factor receptor (EGFR)–mitogen-activated protein kinase (MAPK) transduction pathway (Albanito et al. 2007; Bologa et al. 2006; Filardo et al. 2000; Maggiolini et al. 2004; Revankar et al. 2005; Thomas et al. 2005; Vivacqua et al. 2006a, 2006b). This evidence concerns the gene GPER1 and cancer.