library_construction_protocol: 1 million primary cells of each population in two independent experiments were FACS-sorted as described above. Total RNA was isolated from each cell fraction using the AllPrep DNA/RNA Mini kit (Qiagen, Valencia, CA, USA) according to the manufacturer's instructions. RNA yield and purity were evaluated using a NanoDrop 1000 spectrophotometer (NanoDrop Technologies/Thermo Scientific, Waltham, MA). Quality and integrity were determined by RNA 6000 Nano kit with a Bioanalyzer 2100 (Agilent Technologies, Santa Clara, CA). The ratio of absorbance at 260 and 280 nm was ≥1.9 and the RNA integrity number (RIN) was >9 for all samples. Sequencing libraries were prepared with ribosomal RNA (rRNA) depletion using a Ribo-Zero Gold kit (Epicentre) followed by Apollo 324 NGS Library Prep System (WaferGen Biosystems, Fremont, CA, USA). Sequencing libraries were prepared with ribosomal RNA (rRNA) depletion using a Ribo-Zero Gold kit (Epicentre) followed by Apollo 324 NGS Library Prep System (WaferGen Biosystems, Fremont, CA, USA). The prepared libraries were sequenced on an Illumina HiSeq 2000 (Illumina, San Diego, CA) with 100 base pairs (bp) paired-end RNA-Seq reads.