design: Total RNA was extracted using the RNeasy Plus Mini Kit (Qiagen) following the manufacturers instructions. Paired-end sequencing libraries were prepared by Novogene using the TruSeq Stranded Total Sample Preparation kit (Illumina), followed by quality control, cluster generation, and sequencing on the Illumina HiSeq 2000 platform. Sequence alignment was performed by STAR software to align for RNA-seq data analysis and for the junction reads against the UCSC mm10 assembly.