Induces cell attachment and spreading and plays a role in cell adhesion (PubMed:12235007). Enhances incorporation of BMP1 in the fibronectin matrix of connective tissues, and subsequent proteolytic activation of lysyl oxidase LOX (By similarity). Homodimer (PubMed:29754429). Interacts with BMP1 and fibronectin. Colocalizes with BMP1 in the Golgi. Widely expressed with highest levels in aorta, stomach, lower gastrointestinal tract, placenta, uterus, thyroid tissue and breast. Up-regulated in epithelial ovarian tumors. Not expressed in normal ovaries. Also highly expressed at the tumor periphery of lung carcinoma tissue but not within the tumor. Overexpressed in breast cancers. Gamma-carboxylation is controversial. Gamma-carboxyglutamated; gamma-carboxyglutamate residues are formed by vitamin K dependent carboxylation; this may be required for calcium binding (PubMed:18450759). According to a more recent report, does not contain vitamin K-dependent gamma-carboxyglutamate residues (PubMed:26273833).