Promotes renal phosphate excretion and inhibits intestinal phosphate absorption (PubMed:14962809, PubMed:19005008). Promotes bone mineralization by osteoblasts and cartilage mineralization by chondrocytes (PubMed:18162525, PubMed:19998030, PubMed:22766095). Regulates the mineralization of the extracellular matrix of the craniofacial complex, such as teeth, bone and cartilage (By similarity). Promotes dental pulp stem cell proliferation and differentiation (PubMed:22341070). Interacts (via the ASARM motif) with PHEX; the interaction is zinc-dependent. Expressed by osteoblasts (PubMed:10945470, PubMed:11414762, PubMed:15108058). Expressed by stem cells in dental pulp (PubMed:15153459). Expressed by mesenchymal cells in dental papilla and dental pulp (PubMed:18547474, PubMed:22341070). Expressed in teeth, specifically in decidious dentin (PubMed:20581062). Expressed in ondotoblasts (PubMed:12489176). Expressed in salivary glands (PubMed:15329369). Secreted from oncogenic hypophosphatemic tumors (PubMed:11414762). The acidic serine aspartate-rich MEPE-associated (ASARM) motif is sufficient when phosphorylated to inhibit bone mineralization by osteoblasts and cartilage mineralization by chondrocytes by binding hydroxyapatite crystals during the mineralization stage (PubMed:15664000, PubMed:18162525, PubMed:18597632, PubMed:19998030, PubMed:22766095). It can also inhibit dentin mineralization (PubMed:20581062). The dentonin region is sufficient to promote dental pulp stem cell proliferation (PubMed:15153459). It can also stimulate bone formation, osteoblast differentiation, and activate integrin signaling pathways (PubMed:15040834). Phosphorylated on serine residues in the ASARM motif (in vitro) by FAM20C; the phosphorylation is important for the inhibition of bone mineralization (PubMed:19998030, PubMed:22582013). Cleaved by CTSB/cathepsin B; the cleavage is blocked by metalloprotease PHEX. Belongs to the PF07175/osteoregulin family.