library_construction_protocol: Cells were sorted and frozen in 10% DMSO/FCS. Frozen cells were thawed, washed in PBS, and lysed. Transposition was performed at 42°C for 45 min. DNA was purified with the MinElute PCR purification kit (Qiagen) DNA was amplified for 5 cycles. Additional PCR cycles were evaluated by real time PCR. Final product was cleaned by Ampure Beads at a 1.5Å~ ratio. Libraries were sequenced on a Hiseq 2500 1T in a 50bp/50bp Paired end run, using the TruSeq SBS Kit v3 (Illumina).