library_construction_protocol: HeLa Tet-Off (Clontech) cells were maintained at 37° C, 5% CO2 and 90% humidity in Dublecco's Modified Eagle Medium (DMEM, Thermo Fisher Scientific) supplemented with 9% fetal bovine serum (FBS) and Penicillin-Streptomycin (both Thermo Fisher Scientific). For siRNA transfection, cells were reverse transfected with 60 pmol siRNA targeting RNPS1 (or Luc in the negative control) per 2-3 x 10^5 cells using 2.5 μl Lipofectamine RNAiMAX. Total RNA was extracted using peqGOLD TriFast (VWR Peqlab), followed by using the DIRECTzol Miniprep Kit (Zymo Research) according to the manufacturer's instructions. Ribosomal depletion and strand specific library preparation was carried out with TruSeq Stranded Total RNA (with Ribo-Zero Gold) according to the manufacturer's instructions.