We thank the staff members of the Research Support Facility at the Wellcome Trust Sanger Institute, the Laboratory of Molecular Medicine at IMOMA, and those at the Transgenic Animal Unit, the Molecular Histopathology Unit, the Department of Biochemistry and Molecular Biology and the Biobank of the Principality of Asturias at IUOPA, for excellent technical assistance. This work was supported by grants from the Wellcome Trust (grant no. 098051; A.B.), the Ministerio de Economia y Competitividad-Spain (grant no. SAF2014-52413; C.L.-O.) and the German Research Society (grant no. SFB1243; R.R.), as well as by funding from the Fundacion Maria Cristina Masaveu Peterson (J.C.), the Fundacion Centro Medico de Asturias (J.C.), the Fundacion Bancaria Caja de Ahorros de Asturias/Liberbank (J.C. and A. A.), FEBS (J.d.L.R. and J.C.), CIBERONC (Plan Feder) (C.L.-O.), the Progeria Research Foundation (C.L.-O.), the EDP Foundation (C.L.-O.) and the German Cancer Consortium (R.R.). G.S.V. is funded by a Wellcome Trust Senior Fellowship in Clinical Science (WT095663MA). J.d.l.R. is a recipient of a FEBS Long-Term Fellowship and was a recipient of a fellowship from the Fundacion Maria Cristina Masaveu Peterson during part of this work. J.C. was a recipient of a FEBS Long-Term Fellowship in the initial phases of this work.