Regulation of histone modifications and RNA pol II binding in highly regulated genes. The mean binding density of each of the indicated modifications is shown averaged across the length of an average gene from 2 kb upstream of the TSS to 3 kb downstream of the gene terminus for the set of 126 induced genes (solid line) and 536 repressed genes (dashed line). Blue lines represent the mean binding density for each mark in enriched CFU-Es; and red lines, densities in late erythroblasts.