GPER1 and endometrial cancer: GPER has been reported to be involved in drug resistence in response to the SERM tamoxifen [51–54], the ability of tamoxifen to stimulate proliferative signaling and cell migration in endometrial cancer cells [55–57], as well as proliferative signaling and cell adhesion observed in response to the SERD ICI182,780 [55, 58].