PRF1 and neoplasm: Tregs express immunoregulatory molecules (PDL1 and CTLA4) and produce immunosuppressive cytokines (IL-10, IL-35, TGF-β), which inhibit the synthesis of TNF-α, IFN-γ and IL-17 in Th1 and Th17 cells and reduce the production of perforin and granzymes in CTLs, alleviating their anti-tumor properties [25].