The aberrant activation of RTK/PI3K signaling in GBM has multiple causes: the frequent amplification/mutation of EGFR (~ 45%), the mutation/homozygous deletion of PTEN (~ 36%) and the mutation of PI3K (~ 15%); these mutations collaboratively activate this pathway in ~ 88% GBM patients [4]. The gene discussed is PTEN; the disease is glioblastoma.