Total RNA from cultured primary MEF was extracted using RNAeasy Mini Kit (Quiagen) as per the manufacturer ́s instructions. DNA was removed by on-column digestion using the RNAse-Free DNAse Set (Quiagen, 79254) and RNA concentration was determined with a NanoDrop. High quality RNA was used for downstream application. mRNA-sequencing libraries were prepared using 200 ng of total RNA using NEBNext Ultra II Directional RNA library prep kit with UMI Adaptors. The libraries were pooled equimolarly and sequenced on 2 lanes of Hiseq 3000/4000 with the following configuration: 51+19+8 (single read).