Overexpression of heparanase enhances U251n cell growth. (A) U251n-hpa showed increased cell proliferation as measured by MTT assay. Four days after cell seeding, the numbers of U251n-hpa cells were significantly increased as compared to U251n-pc cells. **, P < 0.01, compared with U251n-pc cells. (B) U251n-hpa cells developed more and bigger colonies than U251n-pc cells as measured by colony formation assay. **, P < 0.01, compared with U251n-pc cells.