Insulin-Secreting Beta Cells 1 (IMAGE) Penn State Caption The insulin-secreting beta cells (green) normally exhibit a perinuclear cap of proinsulin (orange in left panel) whereas proinsulin is spread throughout the cytoplasm (orange in right panel) in many beta-cells of PERK-deficient mice, which are diabetic because of insufficient secretion of insulin. Credit Wei Zhang, Penn State Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.