Lung Repair (IMAGE) University of Pennsylvania School of Medicine Caption Better understanding how sonic hedgehog gene works has implications for treating such disorders as COPD and asthma. The red areas are lung epithelial and mesenchymal cells proliferating and regenerating -- governed by activity of hedgehog proteins -- in the airways of an injured lung. Credit Ed Morrisey, PhD, Perelman School of Medicine, Penn 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.