PTEN and glioblastoma: Combined therapy using adenovirus encoding phosphatase and tensin homolog (PTEN) gene, which is an oncosuppressor, and LY294002, the selective phosphatidylinositol 3-kinase (PI3K) inhibitor, led to significant induction of apoptosis in U251 glioma cells in vitro and in U251 subcutaneous glioblastoma xenograft model in vivo [87].