1x10^6 cells were resuspended in 500 µl TRIzol Reagent (Thermo Fisher Scientific) and their total RNA was purified according to the manufacturer's instructions. Libraries of sequences close to the 3' end of polyadenylated RNA were generated with a QuantSeq 3' mRNA-Seq Library Prep Kit FWD (Lexogen). 3' mRNA-Seq