ROS production was measured using a chemiluminescent substrate (relative light units, RLU). Neutrophils were infected with: wild type (PAO1), a T3SS null mutant (ΔpscD), as well as: (A) a strain lacking the translocation apparatus (ΔpopBD), a strain lacking all 3 effectors (Δ3TOX), and a strain lacking exoS and exoT effector genes (ΔexoST). (B) a strain lacking exoS (ΔexoS), a strain lacking exoT(ΔexoT), or (C) strains with chromosomal point mutations inactivating the Rho-GAP (G-) or ADP-ribosyltransferase activities (A-) of ExoS and/or ExoT. A time course representative of at least three independent experiments is shown. See also Figure S2.