CCL2 and glioblastoma: The presence of necrotic cells within GBM stimulates the expression of TAM chemokines, like the C–C motif chemokine ligand 2/monocyte chemoattractant protein-1 (CL2/MCP-1) and CCL20/MIP-3α (macrophage inflammatory protein 3 alpha), via NF-κB activation, enhancing microglia and macrophage infiltration and attenuating inflammation and apoptosis within the tumor [26], as shown in Figure 1.