Penn Researchers Probe Proteins (IMAGE) University of Pennsylvania School of Medicine Caption Artist rendering of calmodulin molecule depicting protein 'dark energy.' Credit Mary Leonard and Michael Marlow, PhD, University of Pennsylvania School of Medicine 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.