The cells were collected, and RNA was extracted using ZYMO RESEARCH Quick-RNA Miniprep kit (#R1055). After the confirmation of the RNA quality using Agilent 2100 Bioanalyzer, the libraries were prepared with polyA selection using the Truseq RNA Library Prep Kit, and the libraries were sequenced at an average depth of 30M paired-end 100bp nucleotide reads. After the quality of reads was examined using FastQC (v0.11.7, https://www.bioinformatics.babraham.ac.uk/projects/fastqc), paired-end reads were aligned against mouse mm10 genome (iGenome,https://support.illumina.com/sequencing/sequencing_software/igenome.html) using HISAT2 (v2.0.5,http://daehwankimlab.github.io/hisat2).