CLDN18 and pancreatic intraductal papillary-mucinous neoplasm: Other proteins, such as HOOK1, TYMP, TEX12, FBN1, CLDN18, THY1, MUC5AC, CST6, WFDC2, PIK3IP1, and SERPINA4, were predominantly expressed in LGD or invasive IPMN but not in other groups (Fig. 8, Additional file 1: Fig. S7).