The nuclear factor erythroid 2-related factor (Nrf2) is a transcription factor that induces the expression of antioxidant and phase II proteins by binding to the ARE (antioxidant response element) region of the gene promoter. Under basal conditions, Nrf2 is retained in the cytosol by binding to the cytoskeletal protein Keap1. Upon exposure to oxidative stress and other ARE activators, Nrf2 is released from Keap1. It then translocates to the nucleus, where it can bind to the ARE and activate expression of antioxidant and phase II proteins that protect the cell from oxidative damage. Because Nrf2 activation leads to a coordinated antioxidant and antiinflammatory response, and Keap1 represses Nrf2 activation, Keap1 has become a very attractive drug target.