The close inverse relationship between Wy-14,643 stimulation and constitutive suppression in Cyp1b1-ko mice strongly supports the hypothesis that these genes are stimulated by endogenous activation of PPARα, and that this activation is extensively suppressed in Cyp1b1-ko livers. To test whether these genes retained responsiveness in Cyp1b1-ko mice, we measured responses of three strongly expressed genes that are most highly suppressed by Wy-14,643 treatment in the WT mice by real-time qPCR. Vnn1 and Cyp4a14 (Figure 6D) and Cyp4a10 (data not shown) were each induced by at least 7-fold in Cyp1b1-ko mice.
