Involved in the proliferation of osteoblasts during bone formation and bone regeneration. Promotes matrix assembly. Highly expressed in the spleen. Moderately expressed in the skin, lung and urinary bladder. Weakly expressed in the brain, tongue, esophagus, stomach, large intestine, liver and bone. Expressed in osteoblastic cells during bone regeneration. Expressed in secretory osteoblasts in the tooth. At 15 dpc embryos, weakly expressed in osteoblasts within the distal area of the ossification center of the mid-shaft region of the ulna and the radius. At 16 dpc embryos highly expressed in mandible, maxilla, frontal bone and ossification regions of the nasal septum. At 17 dpc embryos expression is localized to developing mandibular and maxillar bones, the frontal bones and in the nasal capsule surrounding the nasopharynx. Expression throughout the developing mandibular bone is found in 15 dpc-17 dpc embryos. Present in periosteum of the humerus at 16.5 dpc (at protein level). Up-regulated during the early phase of the bone regeneration. Up-regulated by BMP2 during osteoblast differentiation.