Figure 4

E-box motifs are enriched at the boundaries of non-CGI HMRs. (a, b) Comparison of 6-mer occurrences surrounding the (a) 5′ unmethylated CG and (b) 3′ unmethylated CG at the boundary of fibroblast-specific HMRs in the top 20% and bottom 20% of in vivo nucleosome peaks. (c) Ratio of observed/expected frequencies of the CACGTG pattern at -5 to +5 CGs for fibroblast HMRs (5′ CG): all HMRs (All, black circle), fibroblast-specific HMRs (black square) and fibroblast-specific HMRs with the top 20% in vivo nucleosome density at the boundary CG (Top 20%, black triangle). (d) Same as in (c) but at the 3′ boundary of fibroblast HMRs (3′ CG).