A peptide PPR agonist (EC50 = 0.15 nM in HEK293 cells expressing human PPR); induces cAMP production in SAOS-2 and UMR106 cells that endogenously express human and rat PPR, respectively (EC50s = 2.2 and 1.1 nM, respectively); stimulates osteoclast-mediated bone resorption in fetal rat long-bone explant cultures and increases collagen synthesis and cell proliferation in neonatal mouse parietal bone explants; normalizes serum calcium levels in thyroidparathyroidectomized rats