1. Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, Biological Sciences Division, University of Chicago, Chicago, Illinois;
2. Departments of Pediatrics, Medicine, Oncology, Radiation Oncology, and Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
3. McKusick-Nathans Institute of Genetic Medicine and Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland