An orthotopic, genetic murine GBM model with a native microenvironment was induced by RCAS/N-tva-mediated somatic PDGF gene transfer in Ink4a-Arf−/−;Pten−/− neural stem/progenitor cells, followed by tumor transplantation into the Tie2-Cre;ROSA-LSL-tdTomato mice (Fig. 1f). The gene discussed is CDKN2A; the disease is glioblastoma.