1. Larry L. Hillblom Islet Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
2. Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California, United States
3. Electron Imaging Center, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, California, United States
4. Molecular, Cellular, and Integrative Physiology Interdepartmental Program, University of California, Los Angeles, Los Angeles, California, United States