To identify the characteristics of lung cancer cells, six NSCLC lines were compared: NCI-H460 and A549 are EGFR wild type (WT) cell lines; PC9 (exon 19 deletion) and HCC827 (exon 19 deletion) are EGFR-mutated (Mut), gefitinib (Gef)-sensitive cells. The gene discussed is EGFR; the disease is lung cancer.