HepG2 cells were disrupted by TRIzol reagent (Invitrogen, Carlsbad, USA). The total RNA isolation and the process of reverse transcription were same as our former report (Wang X. et al., 2016). ABI 7500 sequence detection system was used in performing SYBR-Green quantitative real-time polymerase chain reaction (RT-PCR). The mRNA levels of human CYP2A6, Nrf2, and GSTA1 were normalized to β-actin. The relative change in mRNA gene expression were calculated using the −ΔΔCt method. Primers were designed using Primer Premier5.0 software and were based on the mRNA sequences available at the National Center for Biotechnology Information (Table 1).
