Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): Lung histology from an 18-month-old lysosomal phospholipase A2 null mouse. The lung was perfusion fixed and stained with periodic acid-Schiff reagent. Numerous enlarged alveolar macrophages populate the air spaces, consistent with their foam cell phenotype. The lipid within the cells is due to the accumulation of phosphatidylcholine and phosphatidylethanolamine, the primary substrates of lysosomal phospholipase A2. (See related article in August 2006, vol. 26: issue 16, p. 6139.)