Total RNA was extracted with the TRIzol kit (15596018CN, ThermoFisher). Poly(A) mRNA was isolated using Oligo(dT) beads, fragmented with divalent cations at high temperature, and reverse-transcribed with random primers. Double-stranded cDNA was synthesized, end-repaired, A-tailed, and adaptor-ligated. Adaptor-ligated DNA was size-selected with DNA Clean Beads and amplified with P5/P7 primers. Indexed libraries were validated, multiplexed, and sequenced on an Illumina HiSeq 6000 (2×150 bp paired-end).