Nrf2 silencing abolished the protective effect of Pter. (A) Viability of HaCaT cells incubated for 24 h in different Pter concentrations. Data are presented as percentage of the untreated control ± SD (n = 6); ns = P > 0.05, ***P < 0.001. (B) Pter-induced Nrf2 nuclear accumulation. HaCaT cell treatment with Pter for 24 h. The indicated proteins were detected by western blotting. GAPDH and lamin A were used to confirm the purity of the cytosolic and nuclear extracts, respectively. (C) Relative protein level of Nrf2. Quantitative densitometric data were expressed as fold change, the vehicle was set to 1. Values are mean ± SD (n = 3); *P < 0.05, ***P < 0.001. (D) Nrf2 was silenced by transfecting with siRNA. HaCaT cells were transfected with a specific siRNA against Nrf2 (siNrf2) or a non-silencing control (NC-siRNA). The knocking down efficiency was demonstrated by western blotting using GAPDH as a loading control. (E) Quantification densitometric data from (D). Values are mean ± SD (n = 3); ns = P > 0.05, ***P < 0.001, compared with non-transfection control. (F) Cell viability in HaCaT cells treated as indicated. Data are presented as percentage of the untreated control ± SD (n = 6); ns = P > 0.05, ***P < 0.001.