library_construction_protocol: RNA was isolated with the AllPrep RNA/DNA Micro Kit (Qiagen) following the manufacturer's instructions and stored as recommended. 500pg of RNA was used as input. Reverse transcription and PCR were performed as described (Picelli et al., 2014). Library preparation was conducted on 1ng of cDNA using the Nextera XT DNA Sample Preparation Kit (Illumina) followed by SPRI (Beckman Coulter) size selection. Sequencing was performed by the Biomedical Sequencing Facility at CeMM using the Illumina HiSeq 3000/4000 platform and the 50bp single-end configuration.