PTEN and glioblastoma: CNS-PNET-like tumors were linked to the overexpression of the oncogene MYC, whereas GBM-like cells developed from 3 different sets of genotypes: CDKN2A–/–/CDKN2B–/–/EGFROE/EGFRvIIIOE, NF1–/–/PTEN–/–/TP53–/–, and EGFRvIIIOE/CDKN2A–/–/PTEN–/–.