library_construction_protocol: WT resting Tcm cells were sort-purified from the spleen, crosslinked, digested with three restriction enzymes and underwent proximity ligation. The biotinylated DNA segments were captured, and ligated to the Illumina Paired End Adaptors, followed by amplification by PCR with a low number of cells (18-21 cycles). The resulting libraries were seqeunced with Illumina Hiseq-2000 platform.