Researchers have reported that ROS (reactive oxygen species) and Nrf2 (nuclear factor erythroid 2-related factor 2) are significantly elevated in drug-resistant human non-small-cell lung cancer (NSCLC), and the expression of Nrf2 indicates that elevated ROS levels and an increased antioxidant capacity are common features of drug-resistant lung cancer cells. This evidence concerns the gene NFE2L2 and lung cancer.