In breast cancer, HIF-1α and the G protein-coupled estrogen receptor (GPER) signaling pathway stimulate the expression of VEGF in CAFs, while GPER in breast cancer CAFs induces interleukin-1β (IL-1β) to express interleukin-1 receptor 1 (IL1R1) in breast cancer cells (47). Here, HIF1A is linked to breast carcinoma.