Figure 2

Effects of gefitinib on erbB receptor dimerization patterns and activity of associated downstream signalling elements. (a) Western blot (WB) analysis of phosphorylated epidermal growth factor receptor (p-EGFR), phosphorylated erbB2, phosphorylated tyrosine (Tyr) and total erbB3 protein expression following immunoprecipitation with total erbB3 antibody in tamoxifen-resistant MCF-7 (Tam-R) cells prior to and following incubation of Tam-R cells with gefitinib (1 μM) for 1 hour. (b) WB analysis of total and phosphorylated EGFR, erbB2, AKT and ERK1/2 protein expression in Tam-R cells prior to and following incubation with gefitinib (1 μM) for 1 hour. (c) WB analysis of total and phosphorylated EGFR, erbB2 and erbB3 protein expression following immunoprecipitation with total EGFR antibody in Tam-R cells prior to and following incubation with gefitinib (1 μM) for 1 hour. Tamoxifen (100 nM) was present in all studies. Data are representative of at least three separate experiments.