Lysates were clarified from sonicated nuclei and histone-DNA or protein-DNA complexes were isolated with antibody. Libraries were prepared according to Illumina's instructions. Sorted T cells were fixed by 1% paraformaldehyde, and followed with digestion with Mnase cocktail (Active motif). Chromatin from 5x106 cells was used for each ChIP experiment. Antibodies against H3K4me3 (Cat# 07-473, Millipore), H3K27me3 (Cat# 07-449, Millipore), and Ascl2 mAb (clone, 7E2, Millipore) were used. The pull-down DNA fragments were blunt-ended ligated with Solexa adaptors, and amplified for sequencing. The DNA fragments were sequenced with Illumina 1G Analyzer at the Institute for System Biology.