GR enzyme activities. Transgenic spc–mthGR mice and WT littermates were fed either a control or high-riboflavin diet beginning at 3 weeks of age. At 6 weeks of age the mice were exposed to RA or >95% O2 for 84 hours. Mice were sacrificed and tissues snap-frozen for analyses. GR activities were assessed in 10% lung homogenates by enzymatic assay. Data were natural-log transformed, and 3-way ANOVA indicated individual effects of transgene, diet, and interactions between transgene and diet, transgene and exposure, and diet and exposure. Two-way ANOVA with exposure as a fixed factor and modified t test post hoc were performed to identify individual differences. *Difference compared to WT, same diet; #difference between diets, same genotype; n = 5–22; P ≤ .05.