Transcriptomic profiles of exogenous and endogenous AHR activation. Transcriptional profiling of AHR core-response genes shows little association with AHR-status in the absence of exogenous ligands (A). By contrast, 13 genes were observed to significantly differ based on AHR-status between animals in at least four tissues, with most of these demonstrating higher levels in AHR-less-active animals (B). All fold changes shown are in log2 scale, with the magnitude represented by spot size and q-values are denoted by background shade. Only rat gene names are shown. Genes are ordered alphabetically for AHR core-response genes (A) and by decreasing average absolute magnitude of change across studies for AHR constitutive genes (B).