Melanoma-induced phenotype switching of mature DCs into DCs’ CD14+ variant (characterized by COX-2 or IL-6 expression) leads to a reduction in stimulatory ability toward effector T cells [112]Impaired DC recruitment and maturation mediated by VEGF and TGF-β, leading to decreased cancer cell targeting by T cells [10,114]Wnt/β-catenin pathway-dependent suppression of DCs results in IDO upregulation and, thus, promotion of Tregs’ differentiation and immunosuppressive activity [115,132]. Here, IDO1 is linked to cancer.