PTEN and glioma: Since perifosine was able to penetrate the BBB in previous mouse glioma studies [7], [33], we were able to follow up on the effective synergy we observed in our in vitro culture studies and investigate the effectiveness of this combination in PTEN-intact and PTEN-deficient PDGF-B-driven Ink4a-ARF-deficient gliomas in vivo.