EGFR and glioblastoma: While there have been a limited number of studies on the expression of EGFR, EGFRvIII, which is type III deletion-mutant, ligand-independent, and constitutively active form of the EGFR, there are currently no comprehensive studies of the relative expression and co-expression and prognostic significance of all members of the HER family with EGFRvIII, in patients with GBM.