1. Division of Stem Cell Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
2. Department of Neurosurgery, Brain Research Institute, Niigata University, Niigata, Japan
3. Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
4. Center for Research and Education on Drug Discovery, Hokkaido University, Sapporo, Japan