Periostin was originally isolated as an osteoblast-specific factor that functions as a cell adhesion molecule for pre-osteoblasts and is thought to be involved in osteoblast recruitment，attachment and spreading. Additionally，periostin expression has previously been shown to be significantly increased by both transforming growth factor B1 （TGF-B1） and bone morphogenetic protein 2 （BMP-2）. Abnormal expression of Periostin is also linked to angiogenesis and metastasis in epithelial tumors.
