1. Andrus Gerontology Center, Department of Biological Sciences and Norris Cancer Center, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089–0191, USA.
2. Laboratory of Oncology, Giannina Gaslini Institute, Genova 16145, Italy.
3. Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen 45117, Germany.
4. Laboratory of Experimental Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
5. Animal Research Facility Istituto Tumori, Genova 16145, Italy.