EGFR and glioblastoma: Unlike the ATP-competitive TKIs, PTUPB treatment does not deplete EGF-induced phosphorylation of EGFR (p-EGFRTyr1173) until 6 h post dose, while Gefitinib, a widely-used EGFR TKI, inhibits EGF-induced p-EGFR in early phase (30 min) in glioblastoma cells [37].