The binding domain of claudin-4 and fusion can identify the abnormal localization of claudin in malignant tumors (86), and can be developed as a target for tumor treatment by using the fusion of cCPE and protein synthesis inhibitor (C-CPE-PSIF).The anti-CLDN18.2 mAb (5D12) binds to the second extracellular loop of claudin-4 and human-rat chimeric IgG1 of 5D12 activates the Fc gamma receptor IIIa, thus activating ADCC in CLDN4-expressing cells. The gene discussed is CLDN4; the disease is cancer.