MKI67 and glioblastoma: The proliferative activity of GBM cells, measured by the expression of the nuclear antigen Ki-67, was 50–70% for one case (3.2%), 40–50% for one case (3.2%), 35–40% for four tumors (12.9%), 30–35% for one tumor (3.2%), 25–30% for five tumors (16.2%), 18–25% for five tumors (16.2%), 15–20% for three tumors (9.7%), 8–15% for five tumors (16.2%), and 3–5% for one patient’s tumor, respectively.