Chromatin from formaldehyde-fixed cells (3-5 x 10^6 cells per epitope) was fragmented to a size range of 200 - 700 bases with a Branson 250 Sonifier. Solubilized chromatin was immunoprecipitated with the indicated antibodies and Protein G-Dynabeads (Life Technologies). Immunoprecipitated DNA was extracted with AMP Pure beads(Beckman Coulter) after crosslink reversal, RNAse A and Proteinase K treatment. ChIP DNA samples were used to generate Illumina sequencing libraries following standard protocols.