Chromatin from 10 milions fixed cells was fragmented to a size range of 100–300 bases with a Diagenode Bioruptor. Solubilized chromatin was immunoprecipitated with two different antibody against CSL. Antibody–chromatin complexes were pulled-down using protein A-sepharose, washed and then eluted. After cross-link reversal and proteinase K treatment, immunoprecipitated DNA was extracted with phenol-chloroform, ethanol precipitated, and treated with RNase. ChIPed DNA was quantified by fluorometry on the Qubit system (Invitrogen). A total of 10 ng DNA were used for library preparation using NEBNext® ChIP-Seq Library Prep Reagent Set for Illumina, as recommended by the manufacturer.