This alteration in cell proliferation associated with an altered microenvironment may also be observed in metastasis studies of pancreatic carcinomas where the primary tissue has low expression of CLDN3 while the metastatic cells that invade the liver express high levels of CLDN3 and 4 but show low expression of CLDN1 and 7 [113,114]. This evidence concerns the gene CLDN3 and exocrine pancreatic carcinoma.