1. Primary and Stem Cell Systems, Life Technologies Corporation, Carlsbad, California, USA
2. Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, Maryland, USA
3. Department of Human Genetics, Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA
4. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
5. Buck Institute for Age Research, Novato, California, USA