Cancer inhibits DC maturation through tumor derived-factors such as IL-10 (Williams et al., 2004), macrophage colony-stimulating factor (MCSF) (Nefedova et al., 2004), vascular endothelial growth factor (VEGF) (Gabrilovich et al., 1996), prostaglandin (Sá-Nunes et al., 2007), TGF-β (Zong et al., 2016), and indoleamine 2,3-dioxygenase (IDO) (Munn and Mellor, 2016). The gene discussed is IDO1; the disease is cancer.