design: RNA samples were poly(A) mRNA enriched using the NEBNext Poly (A) mRNA Magnetic Isolation Module. Enriched poly(A) mRNA was transcribed into cDNA using the NEBNext Ultra II RNA Library Prep Kit for Illumina. Adaptor ligation and indexing was done with NEB Multiplex Oligo Kit for Illumina. Library amplification was done in a Roche 480 Lightcycler with EvaGreen as dye. The quality of the libraries was assessed using DNA 7500 Chips on an Agilent 2100 Bioanalyzer. Four nM of each library were pooled and applied to a flow cell for PE75 sequencing on a NextSeq 500 System.