1. Ben May Institute for Cancer Research,1
2. Department of Neurobiology, Pharmacology and Physiology, 2 University of Chicago, Chicago, Illinois 60637;
3. Committee on Cancer Biology, 3 and
4. Quality Controlled Biochemicals, Inc., Hopkinton, Massachusetts 01748 4 ; and
5. Department of Immunology, The Scripps Research Institute, La Jolla, California 920375