RAW 264.7 cells were infected with the indicated recombinant adenoviral vectors at a multiplicity of infection (MOI) equal to 5,000 particles/cell for each vector. In the condition infected with Ad.LacZ alone, a 10,000 particles/cell MOI was used to normalize vector dose to an equivalent level in all conditions. At 48 h after infection, cells were stained for reactive oxygen species (ROS) by using DCFH-DA fluorescent staining. Phase-contrast (top panel) and fluorescent (bottom panel) photomicrographs are shown. Exposure settings were the same for all conditions, and photomicrographs are representative of three independent experiments.