1. INSERM U-344, Endocrinologie Moléculaire, Faculté de Médecine Necker (P.C.-L., V.G., B.B., N.B., P.A.K.), 75730 Paris Cedex 15, France;
2. Cancer Research Program, Garvan Institute of Medical Research (C.O.), Darlinghurst, New South Wales 2010, Sydney, Australia;
3. Hoechst Marion Roussel, Inc.-France (L.L., M.G.-K., R.B.), 93235 Romainville, France;
4. Division of Clinical Pathophysiology, World Health Organization Collaborating Center for Osteoporosis and Bone Diseases, Department of Internal Medicine, University Hospital (P.A.), Geneva, Switzerland;
5. Service Anatomo-Pathologie, Hôpital Necker-Enfants Malades, Université René Descartes Paris V (D.D.), 75015 Paris, France;
6. Departments of Cell Biology and Orthopedics, Yale University School of Medicine (M.A., R.B.), New Haven, Connecticut 06510