Phosphate-dependent stimulation of MGP and OPN expression in osteoblasts via the ERK1/2 pathway is modulated by calcium

► Demonstration of calcium role in regulating the effects of phosphate on osteoblasts. ► Calcium effect on ERK1/2 phosphorylation is not mediated by CaSR. ► Calcium effects involve the formation of calcium phosphate precipitates (CaPp). ► CaPp are not endocytosed, although lipid rafts are necessary to their effects.