(a) Following pretreatment with α-NF (1 – 10 μM), CYP1 and CYP2A activity, and (b) DNA adducts formed by 4-ABP (1 μM) and AαC (10μM) RT4 cells were measured. (c) Following pretreatment with 8-MOP (0.1 – 1 μM), CYP1 and CYP2A activity, and (d) DNA adducts formed by 4-ABP (1 μM) and AαC (10 μM) in RT4 cells were measured (Three independent experiments,*P <0.05; **P <0.01, ***P <0.005 versus Ctrl).