CCL2 and neoplasm: In response to proinflammatory signals (chemokine (C-C motif) ligands 2 and 5 (CCL2 and CCL5), colony-stimulating factor-1 (CSF-1), vascular endothelial growth factor (VEGF), endothelial monocyte activating polypeptide II (EMAP II), and endothelins (ET-1 and ET-2)) the cells of the immune system are recruited to the TME and undergo specific “reprogramming”, e.g., monocytes differentiate into specific tumor-associated macrophages [25,26,27,28].