Treg suppress anti-tumor responses on the level of APC activity, T cell activation, T effector cell functions, and the functions of NK cells by numerous mechanisms, as for example anti-inflammatory cytokines (e.g., IL-10, TGF-β), surface receptor interactions (e.g., negative cross-talk via CTLA-4), IL-2 depletion, and transfer of cyclic adenosine monophosphate (cAMP) [228]. The gene discussed is CTLA4; the disease is neoplasm.