IDO2 and neoplasm: Abbreviations: TILs: tumor-infiltrating-T-lymphocytes; TIBLs: tumor-infiltrating-B-lymphocytes; DCs: dendritic cells; NK: natural Killer; ILCs: innate lymphoid cells (other than NK cells); MDSCs: myeloid-derived-suppressor-cells; TAM: tumor-associated-macrophages; IDO: Indoleamine-2,3-dioxygenase; iNOS: inducible Nitric Oxide Synthase; VEGF: vascular endothelial growth factor.