bulk RNA-seq: Cells were sorted into either 0.1% FAF-BSA/PBS or buffer RLT (Qiagen) supplemented with beta-mercaptoethanol for ATAC-seq and RNA-seq, respectively. Cells sorted into buffer RLT were subjected to total RNA extraction using the RNeasy Micro Kit (Qiagen). ATAC-seq: ATAC-seq libraries were prepared according to the previously described fast-ATAC protocol (Corces et al., 2016). Briefly, 5,000-8,000 FACS-isolated cells in 0.1% FAF-BSA/PBS were pelleted by centrifugation at 400 xg at 4 ˚C for 5 min. Supernatant was carefully removed to leave the cell pellet undisturbed, then cells were washed once with 1 mL ice-cold PBS. The transposition mix [25 µL buffer TD, 2.5 µL TDE1 (both from Illumina FC-121-1030), 1 µL of 0.5% digitonin (Promega, G9441) and 16 µL nuclease-free water] was prepared and mixed by pipetting, then added to the cell pellet. Pellets were disrupted by gently flicking the tubes, followed by incubation at 37 ˚C for 30 minutes in an Eppendorf ThermoMixer with constant agitation at 300 rpm. Tagmented DNA was purified using the MinElute Reaction Cleanup Kit (Qiagen, 28204), and subjected to cycle-limiting PCR as previously described (Buenrostro et al., 2013). Transposed fragments were purified using the MinElute PCR Purification Kit (Qiagen, 28004) and Agilent DNA Tapestation D1000 High Sensitivity chips (Agilent) were used to quantify libraries. RNA-seq: Double-stranded cDNA was synthesized from 5-10 ng RNA using the SMART-Seq2 v4 Ultra Low RNA Kit for Sequencing (Takara) according to the manufacturer's instructions.