Lung Evo Devo (IMAGE) University of Pennsylvania School of Medicine Caption Wnt2+ CPPs (green cells) populate multiple cell lineages in the developing lung including airway and vascular smooth muscle. The smooth muscle of the branching airways and large blood vessels are stained in red. Credit Edward E. Morrisey, Ph.D., 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.