1. INDEGSAL, Cell Biology Area, Molecular Biology Department, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
2. CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
3. Department of Medicine and Health Sciences, Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain