FAS and neoplasm: Several factors have been linked to this impaired immunity, including an immunosuppressive microenvironment resulting from secretion of immunosuppressive cytokines by tumor cells, alterations in Toll-like Receptor (TLR)-9 expression, a reduction of E-cadherin, and a reduced expression of the activator CD3-zeta chain in T lymphocytes, recruitment of regulatory T cells, and presence of death molecules that kill specific cytotoxic T lymphocytes by apoptosis activation through Fas/ Fas Ligand (FasL) signaling (3-14).