PTEN and neoplasm: GFAP-V12Ha-ras mice were generated by overexpressing oncogenic V12Ha-ras in astrocytes, and 95% of these mice died from low- and high-grade astrocytoma within 2-6 months (88). Further expressing a mutant EGFRVIII or inactivating PTEN in GFAP-V12Ha-ras mice demonstrated earlier tumor onset, higher tumor grade and a dramatic reduction in survival (89, 90).