Promotes osteogenesis by stimulating the differentiation of mesenchymal progenitors into mature osteoblasts (PubMed:27976999). Important for repair and maintenance of adult bone (By similarity). Expressed in skeletal tissues including bone marrow, chondrocytes, primary ossification center-associated cells, the perichondrium and periosteum. Lower levels of expression were detected in spleen, thymus, appendix and fetal liver. In the bone marrow, expression is limited to immature neutrophils. Expression was not detected in circulating mature neutrophils. O-glycosylated. Probably sulfated on the O-glycans. Stem cell growth factor