Its engagement by osteopontin physiologically induces macrophage chemotaxis, a mechanism that may be utilized by metastatic brain tumors in the process of dissemination.
Using a number of different brain tumor-derived cell lines we have demonstrated that the mRNA for osteopontin (OPN), which is substantially over-expressed by some tumors in comparison with normal tissues, is preferentially expressed in high grade and metastatic brain tumors compared to low grade brain tumors.