SEL1L immunostaining in normal pancreas and pancreatic adenocarcinoma. In normal pancreas (a), Sel1L is expressed in acinar and islet cells. The staining is cytoplasmic granular diffuse with some perinuclear staining in acinar cells (a1), while endocrine cells show a somewhat weaker stain (a2). Cells in normal ducts are negative (a3), while the smaller ducts show a weak positivity (a4). Examples of pancreatic adenocarcinomas with and without Sel1L expression are shown in panels b and c, respectively. The general concordance between Sel1L and Dpc4 immunohistochemical expression in pancreatic cancer is exemplified by the serial sections of the cases shown in panels d/e and f/g, where the cancer cells invading a perineural space are stained for both Sel1L (d) and Dpc4 (e), while the Sel1L-negative adenocarcinoma associated with the islet of Langerhans (f) is also negative for Dpc4 (g).