Contents

11 June 2013
Vol 6, Issue 279

About The Cover

Cover image expansion

Online Cover This week features a Research Article describing how airway epithelial cells use purinergic signaling to optimize fluid secretion and mucus clearance. Reduced clearance of excessively concentrated mucus occurs in individuals with chronic obstructive pulmonary disease and cystic fibrosis, and the image shows an artist's depiction of lungs, the target organ in these disorders. [Image: Chris Bickel/AAAS]