Furthermore, and as mentioned above, CAFs have also been involved in the alteration of the anti-tumor immune response by the secretion of several immunomodulators [e.g., TGFβ, IL-1β, IL-6, IL-10, indoleamine-2,3-dioxygenase (IDO), arginase (Arg), CXCL2, CXCL5, CXCL12/SDF1, CCL2/MCP-1, CCL5/regulated upon activation, normal T-cell expressed and secreted (RANTES), VEGF, prostaglandin E2 (PGE2), tumor necrosis factor (TNF) or nitric oxide (NO)], that are key regulators of both innate and adaptive antitumor immune responses [17–19, 77] (Figure 2). The gene discussed is IDO1; the disease is neoplasm.