CCL2 and cancer: Cancer cells undergoing angiogenic switch also produce chemoattractants and mitogens, including HIF1-α (hypoxia-inducible factor 1-alpha), VEGF, FGF-1, CCL2 (C-C motif chemokine 2), and CXCL12 (stromal cell-derived factor 1), for endothelial cells and proangiogenic immune cells [22, 23].