Cytotoxic T cells can induce MDSC apoptosis via Fas/Fas ligand (FasL) signaling pathway while resistance to Fas-mediated apoptosis contributes to the presence of MDSC in tumor, and this effect is exclusive in MDSC since other myeloid cells also express a similar level of Fas but do not respond to FasL (25, 26). The gene discussed is FASLG; the disease is neoplasm.