Parathyroid Hormone (PTH)-(1-34),[ Nle8,18,Tyr34]PTH-(3-34) Amide, PTH-(1-31) Amide, and PTH-Related Peptide-(1-34) Stimulate Phosphatidylcholine Hydrolysis in UMR-106 Osteoblastic Cells: Comparison with Effects of Phorbol 12,13-Dibutyrate* *This work was supported by NIH Grant AR-11262 (to P.H.S.).