CCL2 and neoplasm: Nowadays, it is clear that microglia are recruited by tumoral cells thanks to the secretion of different factors such as chemokines, cytokines, etc. One of the principal chemokines involved is chemokine C–C motif ligand 2 (CCL2) that recruits microglial cells through CCR2 and plays a crucial role in promoting tumor growth, neo-angiogenesis and invasiveness, stimulating microglial cells to produce IL-6 [33].