EGFR and glioblastoma: EGFR amplification leads to overexpression of the EGFR at the cell surface, which in turn leads to autoactivation of the EGFR.44 A range of different missense mutations, mostly in the extracellular domain,32,44 are also found in EGFR in glioblastoma, which is different to non-small cell lung cancers where EGFR missense mutations are more commonly found in the tyrosine kinase domain.