Osteopontin expression and function: Role in bone remodeling

The cytokine and cell attachment protein osteopontin (OPN) is not necessary for the development and survival of mice in a clean animal facility. The p rimary role of OPN appears to be that of facilitating recovery of the organ ism after injury or infection, which generally causes an increase in its ex pression. It also is essential for some forms of bone remodeling. OPN stimu lates cellular signaling pathways via various receptors found on most cell types and can encourage cell migration. OPN modulates immune and inflammato ry responses and possibly negatively regulates Ras signaling pathways. Its apparent ability to enhance cell survival by inhibiting apoptosis may expla in why the metastatic proficiency of tumor cells increases with increased O PN expression. J. Cell. Biochem. Suppls. 30/31.92-102, 1998. (C) 1998 Wiley -Liss Inc.