Figure 4. Matrix metallopro-teinase-2 (MMP-2) expression was increased following irradiation, indicating an increase in tumor infiltration.

Representative images of tumor sections were stained for infiltration marker MMP-2 (upper panel; 2× magnification). Increase in MMP-2 expression is noted at the tumor periphery after irradiation, compared with nonirradiated or baseline tumors (middle panel; 40× magnification). A dense expression of MMP-2 is observed in the irradiated tumor. The lower panel shows consecutive sections for negative control for corresponding MMP-2 immunohistochemistry (40× magnification).