Some of these cells secrete chemokines (e.g., CCL2/MCP-1), cytokines (e.g., IL-4, IL-13) and growth factors (e.g., VEGF, CSF1/M-CSF and CSF2/GM-CSF) that trigger the recruitment of monocytes, and can promote cancer progression through the activation of tumor-associated macrophages (TAMs) [14, 15]. The gene discussed is CSF2; the disease is cancer.