NF- κB sites in murine iNOS promoter are essential for C. crepidioides responsiveness. (A) RAW264.7 cells were transfected with a murine iNOS promoter construct (pGL3 iNOS) or pGL3-basic, and then treated with the indicated concentrations of C. crepidioides for 6 h and lysed for luciferase activity analysis. All values were calculated as change (n-fold) in induction values relative to the basal level measured in untreated cells. (B) RAW264.7 cells were transfected with the indicated luciferase reporter plasmids. After transfection, the cells were left untreated or treated with C. crepidioides (250 and 500 μg/ml) for 6 h, and luciferase activity was measured. The activities are expressed relative to that of cells transfected with pGL3 iNOS without further treatment, which was defined as 1. Luciferase activity was normalized relative to the Renilla luciferase activity from phRL-TK. LUC, luciferase. Data are mean ± SD of three independent experiments.