CTLA4 and cancer: In cancer, Tregs dampen anti-tumor immune responses by secreting suppressive cytokines (TGF-β and IL-10), consuming excessive amounts of the T cell growth factor IL-2 (thereby impairing effector T cell proliferation), expressing inhibitory receptors (CTLA-4, PD-1 and LAG3) and inducing tolerogenic dendritic cells (98).