Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): Endosomal activation of NADPH oxidase is shown using H2HFF-bovine serum albumin (BSA) fluorescent detection of superoxides (green). Superoxide production was colocalized with the early endosomal antigen EEA1 (red). The center cell was costained with H2HFF-BSA and EEA1 following interleukin-1 (IL-1) stimulation. The lower right cell was similarly stained but not stimulated with IL-1. The upper left cell was stained with H2HFF-BSA but not for EEA1. The schematic insert depicts the various molecular interactions at the endosomal level that occur following IL-1 stimulation of IL-1R1. (See related article on p. 140.)