Overexpression of heparanase in U251n cells. (A) Heparanase expression of U251n, U87 and primary cultured glioma cells (HF2303) were detected by Western blot. Both U251n and U87 exhibited baseline level of heparanase expression. Latent form of heparanase was detected in HF2303 cells. Increased heparanase expression, both the latent (65 kDa) and active (50 kDa) forms, was observed in cell lysate derived from U251n-hpa cells, as compared to U251n-pc control cells. (B) U251n-hpa cells expressed about 100 times more mRNA than U251n-pc cells. (C) Increased heparanase activity was detected in U251n-hpa cells.