Fig. 2

Impact of EGF and EGFR inhibition by gefitinib on signaling pathway activation and starvation survival of osteosarcoma cells. a The impact of gefitinib (10 μM, 30 min) as indicated on phosphorylation of EGFR, ERK, S6, AKT and GSK3β in IOR-MOS cells either cultured under 10 % FCS (unstarved), serum-starved for 24 h (0 % FCS) or stimulated after serum starvation with EGF (50 ng/ml, 15 min; EGF) or 10 % FCS (10 % FCS) was determined by Western blot analysis. b Densitometric quantification of Western blots (ImageJ Software) from three experiments (one representative shown under a) for the indicated signal proteins. Data are given relative to the phosphorylation levels at serum-starved conditions set as 1. c Viability of IOR-MOS cells was determined by MTT assays after 72 h serum starvation (1 % or 0.1 % FCS as indicated) under increasing EGF concentrations without or with gefitinib (5 μM). Significance of the gefitinib impact: two-way ANOVA with Bonferroni’s post hoc test; * p < 0.05; ** p < 0.01