MGMT and central nervous system cancer: Evidence has shown that several molecules such as Ki-67, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), O-6-methylguanine-DNA methyltransferase (MGMT), and hypoxia-inducible factor 1-alpha (HIF-1α) play important roles in the growth of glioma (16–18).