Chromatin samples were incubated with specific antibodies in ChIP Lysis buffer (50mM HEPES pH7.5, 500mM NaCl, 1mM EDTA, 1%Triton, 0.1%Na-deoxylcholate, 0.3% SDS) overnight at 4℃. The protein-DNA complexes were immobilized on protein A/G beads (10μl per reaction). The bound fractions were washed 3 times with Lysis buffer, and 3 times with RIPA buffer (50mM Hepes, 300mM LiCl, 1mM EDTA, 0.5%NP-40, 0.7%Nadeoxylcholate), and once with TE. Elution and Reverse crosslinking were carried out in Elution buffer (50mM Tris, PH8.0, 1mM EDTA, 1% SDS) 65℃ for 6 hours. After RNase A and protease K digestion, DNA fraction was purified using PCR extraction kit (QIAGEN). ChIP DNA libraries were prepared for sequencing using standard Illumina protocols.