Figure 4.

Effects of gefitinib on MAPK and PI3K/Akt signalling pathways in HER2-overexpressing cancer cell lines. (A) GLM-1 cells were cultured in serum-free medium for 24 h and exposed to gefitinib at increasing concentrations for 2 h at 37°C. Cells were then incubated with either EGF or heregulin (10 or 50 ng ml⁻¹) for 10 min, lysed at 4°C in lysis buffer and subjected to SDS–PAGE, transferred to membrane. Immunoblot analyses were performed with specific antibodies against the phosphorylated Akt and Erk1/2. (B) Gastric cancer cell lines with HER2 overexpression (left) and low expression (right) were cultured in serum-free medium for 24 h and then treated with either gefitinib (1 μM) or vehicle for 2 h. Phosphorylation of Akt was analysed by Western blot. Immunoblot with α-tubulin antibody was performed to evaluate protein loading.