Testes were collected from 6-week-old mice and digested with collagenase, trypsin, and DNaseI. Percoll solution and cell strainers were applied to separate somatic cells from spermatogenic cells. The isolated cells were examined under differential interference contrast optics and 90% of them were spermatogenic cells. ChIP-seq libraries were prepared according to Illumina instructions and sequenced on Illumina's HiSeq2000 instrument.