ERN1 and pancreatic insulinoma: Western blotting for the ribosomal small subunit proteins RPS9 and RPSA in cytosolic and membranous fractions from glucose-stimulated floxed Ire1αFe/Fe insulinoma cells indicated Ire1α deletion in vitro disrupted glucose-stimulated recruitment of the ribosome to the membranous fraction (Fig 5E and S6D Fig).