In response to malignant cell-derived growth factors and chemokines including colony-stimulating factor-1 (CSF-1) (202), VEGF-A (203), chemokine (C–C motif) ligand such as CCL2 (MCP1) (204), CCL18, CCL20 (MIP3a), and CXCL12 (SDF1), bone-marrow derived monocytes or tissue-resident macrophages are recruited into the tumor site and are then termed Tumor Associated Macrophages (TAMs) (205). The gene discussed is CXCL12; the disease is neoplasm.