Appears to regulate cell growth through interactions with the extracellular matrix and cytokines. Binds magnesium and calcium, several kinds of collagen, albumin, thrombospondin, PDGF and cell membranes.

There are two calcium binding sites; an acidic domain that binds 5 to 2 Ca(2+) with a low affinity and an EF-hand loop that binds a Ca(2+) ion with a high affinity. .