By secreting and/or expressing immunosuppressive factors such as IL-10, transforming growth factor (TGF)-β, prostaglandin E2 (PGE2), indoleamine-pyrrole 2,3-dioxygenase (IDO), galectins, and programmed death ligand 1 (PD-L1), cancer cells can locally block CTL-mediated cytotoxicity by causing antigen/MHC loss and T cell dysfunction [88, 90]. The gene discussed is IL10; the disease is cancer.