We ran MotifScanner (39) to search GABR promoters for all vertebrate TF-binding motifs found in TRANSFAC (40) . For each promoter analyzed, we used a prior probability of 0.1 and the corresponding organism specific third-order promoter background model from Eukaryotic Promoter Database (EPD) (41) .We considered positional overlap between Motif-Scanner predictions and putative TFBSs indicative of known binding motifs in our predictions.