Tumor cells can secrete colony stimulating factor-1, chemokine (C-C motif) ligand 2 (CCL2), chemokine (C-C motif) receptor 5 (CCR5), chemokine (C-X-C motif) ligand 1 (CXCL1), and so on, to recruit immunosuppressive myeloid cells toward the TME. The gene discussed is CCL2; the disease is neoplasm.