PPARA and steatosis: The replacement of human PPARα in this study model may not have been sufficient to prevent steatosis and other effects observed in Pparα-null mice; differences in responses between mPPARα and hPPARα mice may reflect functional consequences related to the use of an artificial construct of the reinserted gene, without normal control elements, in addition to or instead of true functional differences between human and mouse PPARα.