Fat Metabolism (IMAGE) Penn State Caption Normal mice fed a diet deficient in leucine do not accumulate fat in their liver (left panel) whereas mutant mice that lack the GCN2 enzyme develop a massive accumulation of fat (severe hepatic steatosis), as seen in the right panel (red droplets). Credit Douglas Cavener Lab, 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.