Receptor activator of NF-kappaB ligand protein expression in UMR-106 cells is differentially regulated by parathyroid hormone and calcitriol.

Expression of the cytokine, receptor activator of NF-kappaB ligand (RANKL), is stimulated by both parathyroid hormone (PTH) and calcitriol in osteoblasts. Most studies have examined the effects on RANKL mRNA, and less information is available on the protein products. We have determined the effects of PTH, the adenylate cyclase stimulator forskolin, and calcitriol, alone and in combination, on endogenous RANKL protein expression in UMR-106 rat osteoblastic osteosarcoma cells by Western blotting and enzyme immunoassay (EIA).