ChIP DNA; cells were crosslinked in growth medium using 1% formaldehyde for 60 minutes in icewater. Fixation was quenched by addition of glycine to a final concentration of 125 mM. After washing, cells were resuspended in RIPA buffer and sonciated using a Covaris S220 (PIP 100 W, DF 20%, 200 CB for 30 min) to generate 180-bp chromatin fragments. Chromatin was precleared using a protein A/protein G-sepharose mixture for 1 hr at 4°C. 200 µl chromatin was incubated with appropriate amounts of antibodies in a total volume of 500 µl RIPA buffer at 4°C over night. After washing and crosslink revearsal, immunprecipitated nucleic acids were purified on GFX columns (GE Healthcare). Input DNA; cells were crosslinked in growth medium using 1% formaldehyde for 60 minutes in icewater. Fixation was quenched by addition of glycine to a final concentration of 125 mM. After washing, cells were resuspended in RIPA buffer and sonciated using a Covaris S220 (PIP 100 W, DF 20%, 200 CB for 30 min) to generate 180-bp chromatin fragments. After crosslink revearsal, nucleic acids were purified on GFX columns (GE Healthcare). The Diagenode MicroPlex library kit was used to prepare libraries from 1-2ng of either input or DIP DNA quantified using the Qubit® dsDNA HS Assay kit (Life Technologies Q32851)