EGFR and glioblastoma: EGFRvIII was found in 38 of these 39 GBM (97%) (Figure 2C), the other case showing an isolated EGFRvIVa deletion in the absence of EGFRvIII. Of note, in five EGFRvIII-mutated GBM, this mutation coexisted with other EGFR mutations/deletions in heterozygous: EGFRvII in two (2%), EGFRvIVa in two (2%), and deletions of exon 25, exons 2–5 and exons 8–28 in one case each; one of these tumors presented simultaneously EGFRvII, EGFRvIII, EGFRvIVa, and del exons 2–5 (Supplementary Table S3).