MSPCs were fixed with 1% formaldehyde, lysates were sonicated and the DNA was sheared to an average length of 300 to 500 bp. Histone-DNA complexes were isolated with specific histone modification antibodies. Illumina sequencing libraries were prepared from the ChIP and Input DNAs by the standard consecutive enzymatic steps of end-polishing, dA-addition, and adaptor ligation. After a final PCR amplification step, the resulting DNA libraries were quantified and sequenced.