Reproducibility of H3K4me3 and H3K27me3 ChIP-seq with the new method . (a) 1Mb region of chromosome 2 containing the transcriptionally active STAT1 / 4 and inactive MYO1B loci, visualised in the IGV genome browser. (b) Heatmap display in IGV genome browser showing triplicate ChIP signals over an 8 Mb region on chromosome 12. H3K27me3 and H3K4me3 signals are shown for 50 and 10 kb window sizes respectively. (c-f) Genome-wide pairwise correlations of read depth in 50 kb (H3K27me3) and 10 kb (H3K4me3) bins for selected replicate samples. Pearson correlation coefficients are given for each comparison. Read depth per bin was normalised to the total number of uniquely mapping reads per sample (reads per bin per million uniquely mapped reads).