Nrf2-dependent induction of GI-GPx promoter activity is reversed by Keap1. (A) The GI-GPx promoter constructs GI-prom-1 to -6 and GI-prom-1-mut were cotransfected in HepG2 cells together with pcDNA3-mNrf2 or with empty pcDNA3. The factor of induction by Nrf2 is shown at the right side. Relative luciferase activity of GI-prom-1 pcDNA3 was set as 1. Potential AREs are indicated by boxes (mutated ARE in black). Values are means of three experiments measured in triplicate ± standard deviation. #, P < 0.05 versus pcDNA3. (B) The GI-GPx promoter construct GI-prom-1 was cotransfected with 10 ng pcDNA3-mKeap1 or pcDNA3 plasmid. Twenty-four hours after transfection, cells were exposed to tBHQ (20 μM), SFN (5 μM), or CUR (25 μM) for 24 h. Relative luciferase activity of the untreated construct without Keap1 was set as 1. Values are means of three experiments measured in triplicate ± standard deviation. #, P ≤ 0.05 versus respective control.