IGF1R and breast cancer: In particular, the functional interaction of GPER with the EGFR, IGF1R, FGFR1, HIF-1α, and Notch transduction pathways may trigger the release of growth factors, such as CTGF, VEGF, and FGF2, and cytokines such as IL-1β that account for important paracrine actions mediated by CAFs toward BC growth and dissemination (Pandey et al., 2009; De Francesco et al., 2013, 2014, 2017, 2018a; Pupo et al., 2014; Ren et al., 2015; De Marco et al., 2016; Santolla et al., 2019; Lappano et al., 2020b).