ROS were determined in hepatocytes, after incubation without or with palmitate (white bars, control hepatocytes; black bars, FMO3 overexpression (A) or knockdown (B)). Student's t test; *, P < .05; **, P < .01; ***, P < .001 vs untreated hepatocytes; #, P < .05 vs control siRNA hepatocytes. C, Fluorescence lifetime measurements were performed as described in experimental procedures on cells expressing ERroGFPiE, an ER-localized redox sensor (Avezov et al [26]). Cells under control conditions exhibited a mean ERroGFPiE lifetime of 1.52 ns in 4 independent experiments. Reduced ERroGFPiE lifetime is indicative of reduced disulphide formation due to a diminished oxidative environment. Data shown are mean ± SEM. Student's t test; *, P < .05.