PTEN and glioblastoma: In the past two decades, focused studies on candidate genes show various genetic alterations typical to GBM, e.g., TP53 mutation and loss, EGFR amplification and mutation, INK4a/ARF mutation, MDM 2/4 amplification or overexpression, PTEN mutation and loss of heterozygosity (LOH) in chromosome 10p and 10q [4, 5].