NFE2L2 and skin cancer: Attempts have been made to develop Nrf2 activators as chemopreventive strategies including photoprotective agents for the prevention of photocarcinogenesis, although it should be taken into consideration that Nrf2 can be the double-edged sword in human cells and a harmful aspect of Nrf2 in the biology of skin cancer has been discussed (Kim et al., 2010; Sporn and Liby, 2012).