ObjectiveA mammalian expression vector encoding TAG72specific single chain variable region(scFv) fused to the transmembrane and intracellular domains of the signal transducing chain of CD28 was constructed, to generate for targeting of genetically modified T cells to gastrointestinal cancer, and to investigate the cytotoxicity against TAG72 positive target cells.MethodsThe transmembrane and intracellular domains of CD28 cDNA was amplified from human T lymphocytes using RTPCR to clone into a mammalin expression vecter, and CD28 fragments were ligated downstream of the antiTAG72 scFv cDNA and sequence verified.ResultsA 729base pair of antiTAG72 scFv was in accordance with sequence concerned; a 240base pair of cDNA of the transmembrane and intracellular domains of CD28 was confirmed as sequence concerning of Genebank.ConclusionWe constructed a mammalian expression vector encoding fusing gene to activate tumorassociated antigenspecific T lymphocyte, for generation of modified T lymphocytes to gastrointestinal tumors.