Genes Activated in the Liver (IMAGE) University of Pennsylvania School of Medicine Caption This image shows color coding of genes that are activated in the liver (yellow) as waves of activation relative to the time of day. "ZT" stands for 'Zeitbeger time,' where ZT0= 7 AM, ZT3=10 AM, ZT6=1 PM, etc Credit Bin Fang, PhD, Perelman School of Medicine, University of Pennsylvania 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.