Figure 3

DNase I hypersensitive (HS) site enrichment at transcription start sites of housekeeping genes. (A) The average density of HS sites detected in CD4+ T cells [35] is shown for each 500 bp sliding window advancing 100 bp each time within 4 kb of the transcription start site for three gene groups, HKGs, all RefSeq genes, and TEGs. (B) RefSeq genes and HKGs are further partitioned into subgroups based on their expression level (probe intensity) in CD4+ T cell profiling microarray: RefSeq-low (intensity < 1), RefSeq-high (intensity > 1), HKG-low (1< intensity < 3), HKG-intermediate (3 < intensity < 6), HKG-high (intensity > 6). The surge of density of HS site around 1500 bp in the HKG-high group is likely an artifact of the small sample size in this group.