Fig. 2.

Western blot analysis of EGFR downstream signaling. BS153 cells were serum starved and stimulated with EGF (20 nM) in the presence or absence of inhibitors (10 µg/mL) or left untreated (A). Serum starvation led to downregulation of wtEGFR phosphorylation (P-), while EGFRvIII phosphorylation (Tyr1068) remained unaffected. EGFR inhibition with erlotinib and gefitinib affected Akt phosphorylation as well as ERK phosphorylation, in the presence or absence of EGF. Cetuximab induced EGFR and Akt phosphorylation in the absence of EGF. Densitometric quantification of phosphorylation events is shown in (B). One of 3 independent experiments is shown.