1. Departments of Pharmacology and Biochemistry, University of Nebraska Medical Center, Omaha, NE 68105.
2. Department of Biochemistry, University of Kentucky, Lexington, KY 40536.
3. Department of Pathology and Microbiology and Eppley Cancer Institute, University of Nebraska Medical Center, Omaha, NE 68105.
4. IGEN, Inc., Rockville, MD 20852.