LGG- or fMLF-induced generation of ROS oxidizes DUSP3. A, SK-CO15 cultured cells transfected with vector control or plasmids expressing DUSP3 or mDUSP3 assayed by immunoblotting for basal levels of phospho-ERK. B, ERK-responsive luciferase reporter gene assay for basal levels of ERK stimulation from SK-CO15 cells transfected with vector control or plasmids expressing DUSP3 or mDUSP3.*, p < 0.05; **, p < 0.001. Error bars, S.E. C, SK-CO15 cultured cells transfected with vector control or plasmids expressing DUSP3 or mDUSP3 or DUSP3 treated with NAC (20 μm) 30 min prior to stimulation with LGG (5 × 107 cfu/ml) or fMLF (500 nm) up to 30 min. Lysates were then assayed for DUSP3 oxidation status by immunoblotting for myc in nonreducing conditions or phospho-ERK by immunoblotting in reducing conditions. All cells were lysed in a buffer containing 10 mm NEM to prevent oxidation of cysteines during sample preparation. DUSP3 oxidation was monitored by changes in electrophoretic mobility. Ox, oxidized DUSP3. myc, reduced DUSP3.