1. Laboratory of Central Nervous System Studies, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
2. Laboratory of Experimental Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
3. Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.