title: GSM1151310: expanded FOXP3+ H3K27me3; Homo sapiens; ChIP-Seq
library_construction_protocol: Cells were crosslinked with 1% formaldehyde and chromatin was sonicated to obtain an average fragment length of 200 to 500 bp. After preclearing with protein A agarose beads (Upstate, USA), sonicated chromatin was precipitated with anti-H3K4m3 and anti-H3K27m3 (abcam, United Kingdom) overnight at 4℃. The immune complexes were bound to protein A agarose beads (Upstate, USA). After washing and elution, crosslinks were reversed at 65℃ overnight. The eluted DNA was treated sequentially with Proteinase K and RNase A, and purified with the QIAquick PCR-purification kit (Qiagen, Germany). The enrichment efficiency of ChIP was detected using qPCR approach. The purified DNA fragments was repaired using PNK and Klenow enzyme, and ligated to adapters.  Subsequently, PCR-amplified fragments of around 100-300bp were sequenced using Illumina HiSeq™ 2000 following manufacturer’s protocols (www.illumina.com).