Average conservation and SymCurv plotted around 1,099 consistent nucleosome-free regions (NFRs) defined through the comparison of two independent datasets (see text for details). The center of the NFR was set as zero. Both forward and reverse complements of each sequence were included in the analysis. Conservation was calculated as mean PhastCons scores over all sites with a specific distance from the centre of the NFR, and SymCurv calculated accordingly. Both curves were smoothed with a running average on a window of 50 bp for better representation.