C ChIP-seq intensities for peaks (promoters + distal) containing the indicated motifs in an interval of ±100 bp around their summit. For most accurate quantitation, intensities were computed within ± 50 bp from the summit. p-values were calculated using Wilcoxon's test. The central band in the boxplot represents the median of the data, boxes the lower and upper quartiles (25% and 75%) and whiskers the minimum and maximum values. 