Knockdown of KLF4 reduces tumorigenic properties and increases gefitinib sensitivity in gefitinib-resistant NSCLC cells with c-Met overexpression, suggesting that KLF4 is an oncogene and contributes to gefitinib resistance in c-Met amplification-mediated gefitinib-resistant NSCLC cells 68. This evidence concerns the gene KLF4 and non-small cell lung carcinoma.