Figure 5. IGF-I activates PI3K/Akt and promotes gefitinib resistance in A431 cells but not in EGFR mutant HCC827 cells.
(A) A431 and HCC827 cells were exposed to IGF-I (10 nM), gefitinib (1 μM), AEW541 (1 μM), or a combination as indicated for 6 hours. Cells were lysed and probed with the indicated antibodies. (B) A431 and HCC827 cells were subjected to a 72-hour MTS survival assay (see Methods) in increasing doses of gefitinib and in the presence or absence of 10 nM IGF-I. Results are presented as percentage of survival compared with cells grown in the absence of gefitinib. Experiments with each concentration of gefitinib were performed 6 times and the mean ± SD are shown.