Kinetics of orange oil-induced antioxidant gene expression. Expression patterns of antioxidant genes HO-1, NQO1, GCLm, and GCLc in BEAS-2B cells at designated times following the 15 min treatment period. Data are presented as fold change from time-matched soy oil-treated controls after normalization to the expression of actin. Presented are results from two separate experiments. The dashed line indicates the 2-fold level of increased expression. Results are expressed as mean ± SEM. * indicates significantly different from time-matched soy oil-treated controls (P < 0.05) by Student's t test.