EGFR and glioblastoma: In fact, we observed the strong expression of a lower molecular weight form of the EGFR in MES GSCs, whose mobility was consistent with that of the truncated EGFR oncogenic mutant, EGFRvIII (Figure 5A, compare the EGFR present in the MES GSC cell lines to the endogenous EGFR expressed in human glioblastoma U87 cells, or with the ectopic expression of EGFRvIII in U87 cells).