CCL2 and neoplasm: The TAMs also stabilize and constitutively express HIF-1α under hypoxic conditions that facilitates the recruitment of macrophages to hypoxic regions of the tumor via the secretion of chemokines, such as CCL2 and endothelins (ETs) (Tariq et al. 2017; Lin et al. 2019; Lugano et al. 2020).