1. Departments of Obstetrics and Gynecology and Cell Biology (D.W.S.), Duke University Medical Center, Durham, North Carolina 27710
2. Receptor Biology Section (J.F.C., K.S.K.), Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709-2233
3. Departments of Biochemistry, Molecular and Cell Biology (A.M., K.E.M.), Northwestern University, Evanston, Illinois 60208-0835
4. Departments of Biochemistry and Child Health (D.B.L.), University of Missouri, Columbia, Missouri 65211
5. Chemical Industry Institute of Toxicology (M.S.), Research Triangle Park, North Carolina 27709-2137