In vitro and in vivo studies of pancreatic cancer showed that overexpression of CLDN4 enhanced cell-to-cell adhesion and prevented cancer cells from engaging in invasion and distant metastasis via the transforming growth factor beta (TGF-β) and Ras/Raf/extracellular-signal-regulated kinase pathways [167]. Here, CLDN4 is linked to pancreatic neoplasm.