design: After total RNA was extracted, mRNA was enriched and then fragmented into short fragments using a fragmentation buffer and reverse transcribed into cDNA with random primers. Second-strand cDNA were synthesized using DNA polymerase I, RNase H, dNTP, and buffer. Then the cDNA fragments were purified, end repaired, had poly(A) added, and were ligated to Illumina sequencing adapters. The ligation products were selected according to size using agarose gel electrophoresis, PCR amplified, and sequenced using Illumina HiSeq2500.