Figure 5.
Expression patterns of matrix metalloproteases MMP-2, MMP-9, urokinase plasminogen activator (uPA) and its receptor (uPAR) measured by immunohistochemistry on postoperative day 3 (n=5), 10 (n=15), 17 (n=15) and 23 (n=5) in the tumor center (core) and in the infiltration zone (IZ), after orthotopic implantation of C6 tumor spheroids. Expression was evaluated semi-quantitatively as the mean of ten consecutive visual fields at ×100 magnification by two independent investigators. The following grading system was applied: 0=no expression, 1=weak expression, 2=intermediate expression, 3=strong expression. MMP-2 and uPA appear early in tumor growth; MMP-9 and uPAR are expressed in late tumor stages.