Vav is required for ROI production in macrophages stimulated with E coli. (A) Oxidative burst was measured by lucigenin chemiluminescence in BMDMs stimulated with unopsonized, heat-killed E coli. Three doses of E coli (40, 80, and 160 million cells) were used to stimulate macrophages. (B) BMDMs were stimulated with CFSE-labeled E coli (40 million cells) for the indicated time points. Free bacteria that had not been phagocytosed by macrophages were washed away, and macrophages were stained with DAPI and mounted on slides for microscopic analysis. (C) Quantitation of the number of E coli internalized by macrophages at 30 minutes. Data represent the mean ± SD E coli ingested per macrophage. Fifty macrophages were scored.