All NIH-3T3 cell lines stably expressing EGFR and/or Mig6 were established by retroviral infections and pooled as described previously37 (link). NIH-3T3 and HEK-293T cells were purchased from ATCC and maintained in DMEM supplemented with either 10% bovine serum or 10% fetal bovine serum, respectively. PC9, HCC827 and A549 cells kindly provided by P. Janne (Dana-Farber Cancer Institute) were cultured in RPMI supplemented with 10% fetal bovine serum. Transient transfection was performed using X-tremeGene 9 (Roche) according to manufacture's instruction. Epidermal growth factor (EGF, Biosource) stimulations were performed using 25 ng/ml for 5 minutes unless noted in the text. All cell lines above except NIH-3T3 cells were authenticated by DNA finger printing analysis (STR analysis).