Hence, estrogenic GPER signaling fosters CAFs to produce a variety of secreted factors that fuel proliferation, migration, invasion, spreading, and EMT of nearby BC cells, as well as tubulogenesis in endothelial cells (De Francesco et al., 2013; Yuan et al., 2015; De Marco et al., 2016; Pisano et al., 2017; Cirillo et al., 2019; Santolla et al., 2019). Here, GPER1 is linked to breast cancer.