Mig6 upregulation is associated with erlotinib resistance.

<p>Head and neck (with PC-3 as prostate), bladder, and lung were treated with indicated doses of erlotinib for 72 hrs and then viable cells were evaluated (<b>A</b>). Value was set at 100% for each vehicle-treated cell line. They were evaluated for total and tyrosine phosphorylated forms of EGFR and Mig6 by immunoblot analysis. β-actin or GAPDH were used as internal loading controls (<b>B</b>). The exposure density of both EGFR and Mig6 blotted on the same membrane were quantified by densitometry and the values of Mig6/EGFR were plotted against IC50 (<b>C</b>). Bladder (<b>D</b>) and lung cancer cell lines (<b>E</b>) were stripped in serum-free medium overnight and treated with vehicle or 10 ng/ml EGF for 10 min, following pretreatment with vehicle or 0.1 µM erlotinib for 3 hrs. Cells were then subjected to immunoblot analysis for phospho-EGFR and total EGFR. β-actin was used as a loading control. Both shorter (p-EGFR-shorter) and longer (p-EGFR-longer) exposure times for phospho-EGFR are shown to provide more detail for each cell line.