Authors' Affiliations: Departments of 1Neurosurgery and 2Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan; 3Department of Neurological Surgery, Johns Hopkins University, Baltimore, Maryland; 4Department of Neurosurgery, Istituto Nazionale Neurologico C. Besta; and 5Department of Biotechnology and Biosciences, University of Milan Bicocca, Milan, Italy (2011-09-13時点)