The authors acknowledge the financial support on the development of nano-therapeutics in cancer granted to E.V. (PI12/00327) and R.M. (PI12/01861) from FIS, to E.V. (TV32013-133930) and to R.M. and A.V. (TV32013-132031) from La Marató de TV3 (416/C/2013), to A.V. from MINECO (BIO2013-41019-P) and from the Centro de Investigación Biomédica en Red (CIBER) de Bioingeniería, Biomateriales y Nanomedicina (NANOPROTHER and NANOCOMETS projects), financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.