the process in vivo to a certain extent. Interestingly, Nrf2 mRNA and protein expressions were dose-dependently increased in HepG2 cells exposed to SA, OA, and ALA, but dose-dependently decreased in HepG2 cells exposed to LA, although still much higher than the control cells. The current reports showed that although LA and its metabolite derivatives play cytoprotective role in HepG2 cells and mouse/rat organs via inducing the expression of Nrf2 and its downstream antioxidative genes (Mollica et al., 2014; Furumoto et al., 2016), LA concentrations higher or lower than the optimal value attenuated its auxo-action on Nrf2 expression (Zeng et al., 2016). However, the exact mechanism of diverse LA concentrations (with similar cytotoxicity) showed different effects on inducing Nrf2 expression remains to be investigated.
