We found novel evidence that an aberration in some steps of EGF-EGFR trafficking from the early endosomes to the late endosomes/lysosomes does occur in the gefitinib-resistant human lung cancer cell line derived from NSCLC, whereas endocytosis of EGFR is normal in gefitinib-sensitive PC9 cells [13], suggesting that impairment in some steps of EGF-EGFR trafficking from early endosomes to late endosomes/lysosomes might confer gefitinib-resistance in NSCLC cell lines. This evidence concerns the gene EGFR and lung cancer.