Location and expression of p-EGFR in A549 and HK2 cell lines. (A) Cells were cultured in medium containing 10% FCS (control) or 10% FCS and EGF (100 ng) for one hour. The labeling for p-EGFR is shown in green, and the nuclei were stained with propidium iodide (red). (B) EGFR and p-EGFR proteins were detected by Western blotting, and β-tubulin protein was used as the loading control. The cells were stimulated for one or three hours with EGF (EGF1 h/EGF3 h). The control cells were maintained in medium without EGF. EGFR expression in A549 and HK2 control cells could not be compared because of different time of film exposure.