GPER1 and cancer: Overall, the discovery of selective agonist/antagonist ligands of GPER has widely aided research toward the evaluation of the specific activities triggered by GPER in different pathophysiological conditions, including cancer (Bologa et al., 2006; Dennis et al., 2009, , 2011; Lappano et al., 2012b; Maggiolini et al., 2015; Prossnitz and Barton, 2011).