1. Departments of Chemistry and Biology, SmithKline Beecham S.p.A., Via Zambeletti, 20021 Baranzate, Milano, Italy, Department of Medicinal Chemistry, SmithKline Beecham Research Unit, B.P. 58, 35762 St-Gregoire Cedex, France, and Departments of Bone and Cartilage Biology and Renal Pharmacology, SmithKline Beecham Pharmaceuticals, 709 Swedeland Road, King of Prussia, Pennsylvania 19406-0939