Glowing Mice (IMAGE) Salk Institute Caption Mice on the left: During fasting, the CREB/TORC2 switch turns on glucose production in the liver. Salk researchers made this process visible with the help of luciferase, which normally produces the glow of firefly tail but in this case lights up the livers of mice actively producing glucose. Mice on the right: In response to feeding, mice produce insulin, which shuts down glucose production in the liver. Credit Courtesy of Dr. Renaud Dentin, Salk Institute for Biological Studies Usage Restrictions News media reproduction to illustrate this story permitted with proper attribution as provided above. For one time use only. 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.