EGFR and glioblastoma: Using a surgical multisampling technique, evidence was provided that EGFR amplification and EGFRvIII mutations differentially evolve during glioblastoma progression: EGFR amplification was observed in all samples derived from individual patients, while EGFRvIII mutations were found only in some subclones of the tumor, thus suggesting that these mutations are events occurring at later times during tumor development [42].