For RNA sequencing, cells were harvested and total RNA was extracted with RNeasy MiniKit (Qiagen) according to manufacturer's instructions. On-column Dnase I digestion was performed followed by mRNA isolation with the NEBNext Poly(A) mRNA Magnetic Isolation Kit (NEB). Library preparation was done with the NEBNext Ultra II Directional RNA Library Prep for Illumina (NEB) following the manufacturer's manual. Libraries were size-selected using SPRIselect beads (Backman-Coulter) after amplification with 9 PCR cycles using the NEBNext Multiplex Oligos for Illumina Kit (NEB). Library quality and fragment size distribution was analyzed on a Fragment Analyzer (Advanced Analytical). Sequencing was performed in paired-end mode on a NextSeq2000 platform (Illumina).