PTEN and glioblastoma: To assess the therapeutic efficacy of this combination therapy in vivo, 5 × 105 PDGF+, PTEN−/−, p53−/−, luciferase+ (MGPP-3) glioblastoma cells that were derived from a proneural transgenic mouse model were implanted subcutaneously as a 1:1 suspension in matrigel.