This work was supported by a grant from the Spanish Ministry of Economy and Competitiveness (SAF2013-45836-R). R.V.-M. and J.G.-A. are supported by fellowships from the Spanish Ministry of Education. The authors thank Fundación Caja Rural de Asturias for financial collaborative support to Laboratorio de Oncología Molecular (HUCA). The Instituto Universitario de Oncología is supported by Fundación Bancaria Caja de Ahorros de Asturias, Spain.