sentence: Probe sets that comprise the Nrf2 biomarker were derived from comparisons using livers of wild-type and Nrf2-null mice treated with CDDO-Im for 6 hrs [ 47 ] and untreated hypomorphic Keap1-floxed mice ( whole body knockdown : Keap1 ) [ 48 ] or additionally featuring hepatocyte-specific targeting ( AlbCre : : Keap1 ) compared to control wild-type mice [ 47 , 49 ] .