NADPH oxidase (Nox)-dependent ROS generation is involved in LTA-induced MMP-9 expression in RBA-1 cells. a Cells were pretreated with or without DPI (1 μM) or apocynin (Apo, 10 μM) for 1 h before exposure to LTA (50 μg/ml) for the indicated time intervals. The conditioned media were analyzed by gelatin zymography for MMP-9 expression and activity. b The total RNA was collected and MMP-9 mRNA expression analyzed by RT-PCR (upper panel) and real-time RT-PCR (lower panel). c Cells were pretreated with or without DPI (1 μM) or apocynin (Apo, 10 μM) for 1 h before exposure to 50 μg/ml LTA for 15 min. The Nox activity and ROS generation were analyzed. d Cells were transfected with scramble (scra) or Nox2 siRNA for 24 h, followed by stimulation with LTA for 16 h. The conditioned media and cell lysates were collected for gelatin zymography or Western blotting analysis of Nox2 and GAPDH (as an internal control). Data are expressed as the mean ± SEM of three independent experiments. *
P < 0.05; #
P < 0.01, as compared with the r cells stimulated with LTA (c) alone. The figure represents one of three similar experiments.