DUSP1 and non-small cell lung carcinoma: This study was conducted to investigate the effect of folic acid (FA) on the resistance of non-small cell lung cancer (NSCLC) cells to Osimertinib (OSM) by regulating the methylation of dual specificity phosphatase 1 (DUSP1).<h4>Methods</h4>The OSM resistant NSCLC cell line PC9R was establishd by gradually escalation of OSM concentration in PC9 cells.