Approximately 1x108 K562 cells were fixed by 10% formaldehyde in 50 mM Hepes-KOH, pH7.5, 100 mM NaCl, 1 mM EDTA, ph8.0, 0.5 mM EGTA, pH8.0 for 10 min at room temperature, quenched by one tenth volume of 2.5 M Glycine, rinsed sequentially with LB1 (50 mM Hepes-KOH, pH7.5, 140 mM NaCl, 1 mM EDTA, 10% glycerol, 0.5% NP-40, 0.25% Triton X-100), LB2 (10 mM Tris-HCl, pH8.0, 200 mM NaCl, 1 mM EDTA, 0.5 mM EGTA, pH8.0), and resuspended in LB3 (10 mM Tris-HCl, pH8.0, 200 mM NaCl, 1 mM EDTA, pH8.0 0.5 mM EGTA, 0.1% Na-Deoxycholate, 0.5% N-lauroylsarcosine) containing Protease Inhibotor Cocktail (Roche). Cell suspension was then sonciated by Covaris S2 Acoustic Solbilyzer with Duty Cycle 20%, Intensity 5, Cycles per Burst 200, and 20-30 cycles. Lysates were cleared by centrifugation, and immunoprecipitated with anti-ASH1 antibodies fixed on Dynabeads M-280 sheep anti-rabbit/mouse IgG (Invitrogen), washed with LiCl buffer (100 mM Tris-HCl, pH7.5, 500 mM LiCl, 1% NP-40, 1% Na-Deoxycholate) and then with TE, and eluted in 1% SDS, 0.1 M NaHCO3. After overnight de-crosslinking, DNA was purified with PCR Cleanup column (QIAGEN). Fragment sizes were checked by 2100 BioAnalyzer (Agilent). Sequencing libraries were constructed using ChIP-Seq Sample Prep Kit (Illumina) according to the manufacture's protocol.