Messenger RNA was purified from total RNA using poly-T oligo-attached magnetic beads following internal protocol. After fragmentation, the first strand cDNA was synthesized using random hexamer primers, while the second strand cDNA was synthesized using dUTP, instead of dTTP. The directional library was ready after end repair, A-tailing, adapter ligation, size selection, enzymatic digestion, amplification, and purification. The library was checked with Qubit 2.0 fluorometer and real-time PCR for cDNA quantification (Thermo-Fisher Scientific), and Agilent Bioanalyzer 2100 system bioanalyzer (Agilent Technologies, Waldbronn, Germany) for the detection of size distribution.