1. Department of Pharmacology and Physiology, Georgetown University, Washington, District of Columbia, United States
2. Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, District of Columbia, United States
3. Department of Biology, Howard University, Washington, District of Columbia, United States
4. Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States
5. Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States