Lack of Shut-Eye, Diabetes, Age (IMAGE) University of Pennsylvania School of Medicine Caption There is increased ER stress in the pancreas of aged mice. Phosphorylation of PERK (P-PERK), indicative of ER stress and activation of the unfolded protein response, is evident in ß-cells. Representative images of P-PERK (green) in B-cells (red) immunostained for insulin in young undisturbed (YC), young SD (YSD), old undisturbed (OC) and old sleep deprived (OSD) mice. Credit Nirinjini Naidoo, Ph.D., Division of Sleep Medicine: Perelman School of Medicine; <i>Aging Cell</i> 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.