Normal vs Mighty Mouse (IMAGE) Johns Hopkins Medicine Caption Comparison of body and muscle size between normal (left) and double mutant mice lacking myostatin and overproducing follistatin (right). Credit Se-Jin lee 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.