1. Centre for Genomic Regulation (CRG) The Barcelona Institute of Science and Technology Dr. Aiguader 88 Barcelona 08003 Spain
2. Universitat Pompeu Fabra (UPF) Barcelona 08002 Spain
3. ICREA Pg. Lluís Companys 23 Barcelona 08010 Spain
4. Basic Sciences Department Faculty of Medicine and Health Sciences Universitat Internacional de Catalunya Sant Cugat del Vallès 08195 Spain