Collectively these data suggest that gradients of chemokines (e.g., CCL2, CCL5, and CCL18) formed in the tumor microenvironment not only recruit monocytes/macrophages but also form de novo chemokine gradients (e.g., `, CCL22, and CXCL8) that reinforce the accumulation of pro-metastatic immune cells such as MAMs, MDSCs and Treg cells (Fig. 2). The gene discussed is CCL2; the disease is neoplasm.