Cells were fixed with 1%paraformaldehyde, the fixation was quenched with glycine, and the fixed cells were snap-frozen and stored at -80C. Cells were slow thawed on ice for 15 minutes, then lysed in 1% SDS lysis buffer. Chromatin was sheared on a water bath sonicator, and IPs were performed using the indicated antibodies and protein G magnetic beads. DNA was decrosslinked and purified using Qiagen PCR purification kit. Libraries were prepped using 5ng DNA and the iDeal library prep kit. Amplification cycles of the library preps were optimized using qPCR.