Gefitinib resistance of cancer cells correlated with TM4SF5-mediated epithelial-mesenchymal transition

► Gefitinib resistance showed sustained TM4SF5 expression and EMT upon gefitinib treatment. ► T790M EGFR introduction into gefitinib-sensitive cells showed EMT and increased TM4SF5 level. ► Regulation of TM4SF5 expression resulted in modulation of gefitinib resistance. ► Suppression of TM4SF5-mediated effects also resulted in reduced gefitinib resistance.