Role of EGFR in neurotensin-induced signalling in HCT116 cells. A, Phosphorylation of the EGFR residue 1173 induced by neurotensin (NT) and EGF. Quiescent cells were pretreated with vehicle (0.5% DMSO) or 10 μM gefitinib for 30 min before stimulation with 1 μM NT or 5 nM EGF for five min. Cells were harvested for subsequent Western analysis as described in Methods. Because of the strong EGFR phosphorylation induced by EGF, we also show the same blot overexposed. Results represent one typical of three independent experiments. B, Phosphorylation of Shc induced by NT and EGF in cells pretreated with vehicle or gefitinib. Results represent one typical of three independent experiments. C, Phosphorylation of ERK and Akt induced by NT (1 μM) and TGFα (10 nM) in cells pretreated with vehicle or 10 μM gefitinib for 30 min before stimulation. Results represent one typical of four independent experiments.