Moreover, microglia phagocytic activity, which is crucial for tumor and metastatic cell clearance, relies on specific receptors expressed on the cell surface (e.g., TLRs, and triggering receptor expressed on myeloid cells 2 (TREM-2)) and their downstream signaling pathways (e.g., NF-kB and IRF3, 4, 5, 7 and 8) [61, 68]. This evidence concerns the gene TREM2 and neoplasm.