Two-month old wild-type (WT) and liver-Cpr-null (LCN) male mice were exposed to 10 ppm of naphthalene (NA) for 4 hours and plasma levels of NA (A) and naphthalene-glutathione conjugate (NA-GSH) (B) were determined at different time points after termination of NA exposure. Data represent means ± SD (n=4). *, **, ****, p<0.05, 0.01, or 0.0001, respectively, compared to WT mice (two-way ANOVA followed by Bonferroni’s test for multiple comparisons).