Cells were treated with 10× stock of an EGF (PeproTech) dilution series for 10 min. Cells were treated with varying concentrations of EGF for 10 min before the evaluation of phosphorylated MAPK amounts by immunofluorescence as previously described (73 (link)) using an Operetta high-content imaging system (PerkinElmer). Data are the average of replicate wells generated using the Columbus image data storage and analysis system (PerkinElmer).