Arctiin inhibits the production of NO (A), expression of iNOS protein (B), and mRNA (C, D) in LPS-stimulated macrophages. RAW 264.7 cells (A-C) and primary macrophages (D) were treated with different concentrations of arctiin (12.5 ~ 100 μg/ml) in the presence of LPS (100 ng/ml) and was monitored as described in 'Materials and Methods'. Each bar represents the means ± S.D. from three separate experiments. ††P< 0.01 compares to the control. **P< 0.01 compared to the LPS.