Top eleven promoter regulatory matrices identified using the F-match module in ExPlain 3.1 (BioBase Knowledge Library) (see Methods).

aRatio of the abundance of each promoter matrix in genes differentially regulated across all six tissues compared to 492 mouse housekeeping genes (see Methods). bPrdm1 (Blimp1), a transcriptional repressor essential for B- and T-cell differentiation and homeostasis, is regulated by Irf4. Prdm1 and interferon regulatory factors bind to similar DNA sequences. Some promoters contain overlapping motifs where Prdm1 and Irf family members may competitively interact.