Furthermore, SPT is positive for claudin-18.2and claudin-7 in a few cases, and pancreatic endocrine tumor (PET), acinar cell carcinoma(ACC), and pancreatoblastoma (PB) show strong expression of claudin-7 and a lack of claudin-5 expression (107). This evidence concerns the gene CLDN18 and pancreatic neuroendocrine tumor.