RNA was extracted using an Rneasy kit (Qiagen), snap frozen, and 600ng per sample was sent to Novogene Co for RNAseq. Library was constructed by Novogene Co. mRNA was enriched using poly-T oligo-attached magnetic beads before fragmentation. First strand cDNA was synthesized with random hexamer primers. Second strand was synthesized using dUTP. End repair, A-tailing, adapter ligation, size selection, USER enzyme digestion, amplification, and purification was then performed.