CD28 and neoplasm: Our findings suggest that in addition to secretion of IFN-gamma and IL-2 according to the specific cytotoxicity against CD20 positive tumor cells by anti-CD20scFvFc/CD28/ζ receptor grafted T cells, Fas/FasL apoptotic pathway also contributes to anti-CD20scFvFc/CD28/ζ gene modified adoptive T cells-mediated cytotoxicity in vivo.