Elf-1 and PU.1 each transactivate the gp91^phox promoter. HeLa cells (A) or PLB985 cells (B) were cotransfected with gp91^phoxpromoter/luciferase reporter and expression vectors as described in Materials and Methods. Luciferase vectors contained either the wild-type −102 to +12 bp gp91^phox promoter or the same promoter fragment into which the −57 bp or −55 bp CGD mutations were introduced. The expression vector that was cotransfected with the luciferase vector is indicated below the graph. Data are presented as the mean ± standard deviation. The number of independent experiments (N) performed for each cotransfection is indicated below, and three different plasmid preparations of each construct were tested.