MinION sequencing
Direct RNA sequencing was performed as described previously (Bilska et al., 2020). 3.5-5 μg of total mRNA was mixed with 50-200 ng oligo-(dT)25-enriched mRNA from Saccharomyces cerevisiae yeast to optimize sequencing efficiency, standards with predefined poly(A) lengths, and unrelated total RNA from mouse macrophages, and processed with a Direct RNA Sequencing Kit (catalog no. SQK-RNA002, Oxford Nanopore Technologies) according to the manufacturer's instructions . Sequencing was performed with MinION device (Oxford Nanopore Technologies, Flow cell type FLO-MIN106; RevD)