Three patient-matched GBM and BTIC cell lines were found to express 16 ± 2% and 14 ± 2% of the EGF(1,2,3,5) isoform, respectively, compared to 4 ± 0.1% among normal human astrocytes (Fig. 3B), a difference that reached statistical significance (p = 0.008). The gene discussed is EGF; the disease is glioblastoma.