1. Life Sciences Division, Berkeley National Laboratory, Berkeley, California 94720 1 ;
2. Voltastrasse 39, 8044 Zürich, Switzerland 2 ;
3. Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892 3 ;
4. Searle Research Division/Monsanto Company, Chesterfield, Missouri 63017 4 ; and
5. Institute for Veterinarian Biochemistry, University of Zürich (Irchel), 8057 Zürich, Switzerland5