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Figure 2 Inhibitory effects of UA extract on nitric oxide (NO) production and inducible-nitric oxide synthase (iNOS) expression in LPS-stimulated RAW 264.7 cells. (a) Cells were pretreated with the indicated concentrations of UA extract for 1 h prior to incubation with LPS (0.5 μg/mL) for 24 h. The nitrite levels in the culture medium were measured by the Griess reaction. Three independent experiments were performed, and the data are presented as the mean ± SEM. *P<0.05 and **P<0.01 compared to the cells treated with LPS alone. (b) Cells were pretreated with UA extract for 1 h and then stimulated with LPS for 6 h. β-Actin expression was used as an internal control for quantitative RT-PCR. (c) Cells were pretreated with UA extract for 1 h and then induced with LPS for 24 h. Ten cell lysates were prepared, and the iNOS protein levels were analyzed on western blots. Expression of β-actin was used as an internal control for western blot analysis.