Figure 2.

RTK inhibitors, erlotinib, gefitinib, AG1478, and PHA-665752, reduce EGFR/c-Met cross activation in U251 and 5310 glioblastoma cells. (A) U251 and 5310 cells were grown in serum-starved medium containing 5 µM erlotinib and gefitinib for 9 hours. Cell lysates were evaluated for the expression levels of total and phosphorylated EGFR, c-Met, Stat3, and β-catenin. (B) Quantitative estimation of A. (C) To study the effect of EGFR phosphorylation of c-Met expression, we treated U251 and 5310 cells with 10 µM AG1478 for 1 hour in serum-starved medium. Expression levels of various molecules were subjected to Western blot analysis. (D) Quantitative estimation of C. (E) The phosphorylation of EGFR, c-Met, Stat3, and β-catenin is substantially reduced by 0.5 µM PHA-665752 in U251 and 5310 cells. Cells treated only with DMSO were treated as controls. Cells were lysed, and the indicated proteins were detected by immunoblot analysis with indicated antibodies. (F) Bar graph quantification values of E. Values are the means ± SE of three independent experiments; *P < .05; **P < .01. All the data represented in this panel are representative of two individual separate experiments. In all the experiments, the Western blots were normalized using GAPDH.