To access the significance of the motif concentration within DGF in each cell type, we compute the DGF enrichment ratio as the ratio between the number of motif instance with distance less than 20bp to the DGF center and that number in the immediate flanking window, that is, the number of motif instance with distance to the DGF center larger than 20bp and smaller than 40bp. As control, we randomly sampled the same number of motif instances from the shuffled versions of the given motif, and obtained the DGF enrichment ratio for the shuffled motif instances. The DGF enrichment ratio of the true motif is further converted to z-score by mean and standard deviation from the DGF enrichment ratios of shuffled motif from 1000 times random sampling. Then the adjusted p-value is further computed from z-score and bonferroni correction for number of cell types.
