Chromatin modification profiling of hematopoietic stem cell lineage commitment. (A) Genome-wide distribution of histone H3 modifications and PolII on promoters in HSCs, MPPs, PreMegEs, and T cells using HD 2.1M promoter arrays. (B) Correlation between histone modifications and gene expression in the different cell types. Genes were grouped into bins of 100 genes based on their expression levels. The average log₂ enrichment of each histone modification was determined for each bin and plotted to assess correlation trends. (C) Association of histone modifications and PolII with the promoters of Lmo2 (chr2; left panel) and TcR Vβ13 (chr6; right panel) in HSCs, MPPs, PreMegEs, and T cells. Each box represents the tiled region (−8.2 to +3 kb from TSS), with the arrow near gene name indicating the direction of transcription and the TSS is shown as a green vertical line. Data are displayed as log₂ ChIP/input probe signal ratios (black) with the overlaid red, orange, and yellow boxes representing peaks with FDR ≤ 0.05, ≤ 0.1, and ≤ 0.2, respectively. The x-axis shows the chromosomal coordinates, and the y-axis shows the log₂ enrichment values of probes and peaks.