Claudin-4 is highly expressed in pancreaticobiliary ductal PCa (p = 0.015), PanIN, IPMN, MCN, and the major precursor lesions of pancreatic ductal adenocarcinoma (73), and its expression is correlated with the histological tumor grade of IPMN and MCN (11, 23, 34, 57). Here, CLDN4 is linked to neoplasm.