1. Department of Biochemistry, Molecular Biology and Cell Biology, and Center for Reproductive Science, Northwestern University (A.D.B., K.E.M.), Evanston, Illinois 60208
2. Reproductive Endocrine Unit, Massachusetts General Hospital, Harvard Medical School (A.M.), Boston, Massachusetts 02114
3. Molecular Mechanisms in Development Group, Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Cancer Institute (E.S.), Frederick, Maryland 21702-1201
4. Eukaryotic Transcriptional Regulation Section, Laboratory of Protein Dynamics and Signaling, National Cancer Institute (P.F.J.), Frederick, Maryland 21702-1201