Cells were fixed in 1.1% formaldehyde in phosphate-buffered saline for 10 min at room temperature. Nuclei were extracted in a hypotonic buffer and chromatin was sheared by sonication. Immunoprecipitation was done using 10 ug of Flag M2 antibody (Sigma) and Protein G dynabeads (Invitrogen). DNA was amplified using ThruPLEX kit (Rubicon Genomics)