Examples of variation among cell types in the extent of broad regions of H3K27me3. A. HOXC cluster region of chromosome 12. Note the large differences between B73 and B12 in particular. Left axis is log2 enrichment ratio. B. Region of chromosome 6. Large arrow indicates differential region, which encompasses transcription start site for FOXP4 gene (gene indicated by smaller arrow in Transcripts track). Note particularly large difference between B73 and fNSC. Markings for “Transcripts” tracks: boxes above the line indicate transcripts that are on the + strand (i.e. TSS (transcription start site) on left side of box), while boxes below the line represent transcripts that are from the opposite strand (i.e. TSS is on right of box).