Whereas the CSF-1/CSF-1R axis is essential to the differentiation of myeloid cells including granulocytes, macrophages, and dendritic cells, the C-C motif chemokine receptor 2 and chemokine receptor 5 (CCR2 and CCR5) are important mediators of myeloid cell migration to nonhematopoietic organs and tissues including TME of pancreatic, colorectal, hepatocellular, and lung carcinomas. The gene discussed is CCR2; the disease is lung carcinoma.