library_construction_protocol: Total RNA was extracted using RNeasy Plus Micro Kit (74034; Qiagen) according manufacturer's instructions. 3,8 - 12,7 ng of total RNA was used for the construction of sequencing libraries For the preparation of NGS libraries from low-input samples we followed the Smart-seq2 protocol. The subsequent library preparation from the amplified cDNA was performed using the Nextera XT DNA library prep kit (Illumina). Library concentrations were quantified with the Qubit 2.0 Fluorometric Quantitation system (Life Technologies) and the size distribution was assessed using the 2100 Bioanalyzer instrument (Agilent). For sequencing, samples were diluted and pooled into NGS libraries in equimolar amounts.