CCL2 and cancer: Cancer cells can secrete both monocyte and macrophage chemotactic factors, e.g., C-C motif chemokine ligand 2 (CCL2), as well as the agents that accelerate the maturation of these cells and activate them, e.g., the colony stimulating factor 1 (CSF1) and CSF2, and also inhibit their chemotaxis [4,6,8,17].