Figure 1From: EGFR/Met association regulates EGFR TKI resistance in breast cancer Met expression mediates EGFR tyrosine phosphorylation and proliferation in the absence of EGFR kinase activity. (A) SUM229 cells were infected with lentiviral particles containing Met shRNA or a non-silencing shRNA for 72 hrs. Cells were treated with gefitinib for the last hour of infection at 0.5 μM, cells were lysed, and lysates were immunoprecipitated with anti-EGFR. Immunoprecipitates were immunoblotted with anti-EGFR, anti-Ptyr, and the indicated phospho-specific sites on the EGFR. Corresponding whole cell lysates were immunoblotted with anti-Met and β-actin as a loaded control. Through quantification, EGFR phosphorylation was decreased by 53% in the gefitinib treated cells and 88% in the gefitinib with Met knocked down cells. The two bands in the Met immunoblot represent processed and pro-forms of Met. (B) SUM229 cells were infected with lentiviral particles containing Met shRNA in the presence of gefitinib or a non-silencing control for seven days in the presence of puromycin to select for infected cells. Cells were counted using a Coulter Counter and the day 8 values were graphed with the error bars representing SEM.Back to article page