Add final concentration of 1% Formaldehyde solution for Cross-Linking of DNA and Protein. Then stoped the cross-linking reaction by adding final concentration of 125mM glycine. Extract chromatin from cross-linked cells by adding Lysis Buffer The sequencing libraries of immunoprecipitated chromatin DNA were generated with varied index label by NEBNext® UltraTM DNA Library Prep Kit for Illumina (NEB, USA, cat. E7645L). Libraries were amplified using 8-10 cycles on the thermocycler. Post amplification libraries size was selected and then purified with AMPure XP Beads. Qubit was used for library quantification and High-sensitivity DNA chip was used for test of library insert size.