A. shNrf2 plasmids were transfected into high Nrf2-expressing (H1299 and H358) cell lines compared with both cell types transfected with a non-specific shRNA (NC), Nrf2 expression plasmids were transfected into low Nrf2-expressing (H1975 and CL3) cell lines compared with both cell types transfected with an empty vector (VC). After 24h, the indicated cells were incubated with or without cisplatin (0, 2, 4, 8, 16, 32 μM) for 48 h for MTT assay. The cell lysates were separated by SDS-PAGE for the evaluation Nrf2 expression by specific antibodies using western blotting. The MTT assay was used to determine the 50% inhibition concentration (IC50) of cisplatin. B. H1299 cells were transfected with p53 and/or Nrf2 plasmid. H1975 cells were transfected with shp53 and/or shNrf2 plasmid. After 24h, the indicated cells were incubated with or without cisplatin for 48 h for MTT assay. The cell lysates were separated by SDS-PAGE for the evaluation p53, Nrf2, HO-1, Bcl-2 and Bcl-xL expression by specific antibodies using western blotting. The MTT assay was used to determine the IC50 of cisplatin.