CLDN4 and prostate intraepithelial neoplasia: Also, in primary pancreatic cancer sections, Nichols et al (2004) reported that immunohistochemical expression of claudin-4 was present in pancreatic intraepithelial neoplasia cells and in all of the metastatic cancers examined (Nichols et al, 2004) reflecting our observation that claudin-4 expression was present in all HG-PIN sections associated with PCa.