As we observed that omission of recombinant Egf from the culture medium increased expression of EgfrvIII in the BAH1 cell line (data not shown), it may be worthwhile to routinely establish GBM cell lines both in the presence and absence of Egf in the culture medium in order to attempt to increase the frequency at which Egfr/EgfrvIII-amplified cell lines are established. Here, EGFR is linked to glioblastoma.