EGFR and neoplasm: Notably, GBMs often contain stably mosaic cellular compositions, including the concomitant presence of tumor cell subsets with and without EGFRvIII mutation, or co-existing tumor micro-regions harboring cell subpopulations with oncogenic amplifications of either EGFR or PDGFR genes (Biernat et al., 2004; Ramnarain et al., 2006; Inda et al., 2010; Snuderl et al., 2011).