Like gastric inhibitory polypeptide and glucagon-like peptide-1, gastrin has also been shown to induce b-cell proliferation and neogenesis in various model systems, and also appears to increase the insulin content of individual cells. Zollinger and Ellison's original description of peptic ulcer disease attributable to purported gastrinoma included one case where "the pancreatic tissue removed with the tumor showed normal islands with many large cells…". Examination of another case with resected pancreas adjacent to an antral gastrinoma "showed a marked proliferation of ducts and islet tissue" with "development of islets from cells (nesidioblasts) within the duct epithelium.