FOXP3 and neoplasm: However, more and more evidence has shown that increased numbers of Tregs in tumor-infiltrating lymphocytes (TILs) or peripheral blood mononuclear cell (PBMCs) may be one of the reasons why the host has impaired tumor immunity.[5,6] Tregs can directly contact cells or secrete immunosuppressive cytokines to indirectly inhibit the functions of effector T-cells.[7,8] FOXP3 predominantly expressed within the nuclear functions as a type of forkhead box transcription factor containing a DNA-binding domain.