For transfection of shRNA, lentiviral particles encoding Nrf2 or non-target shRNA (Sigma-Aldrich, St. Louis, USA) were diluted in OptiMEM (Gibco, Grand Island, NY) containing 6 μg/mL polybrene, and then were added to SW1990/Gem and Panc-1/Gem cells. After 3 days, 5 μg/mL of puromycin were used to select transfected cells. Cells transfected with the shRNA lentiviral particles were seeded into six-well plates and western blot analysis were used to detect the protein level of Nrf2. Nrf2 plasmid was obtained from Prof. Siwang Yu from Peking University (Beijing, China) and transfected into cells according to the manufacturer's instruction of ExFect transfection reagent (Vazyme, Nanjing, China).