The cells were left untreated (no virus) or infected with one of the recombinant adenoviruses (Ad-Mock, Ad-CYP2A6, and Ad-CYP2A13). The adenovirus-mediated mRNA expression of CYP2A6 and CYP2A13 were determined with qPCR. The mRNA levels are presented as means±SD, n=3 (A). Protein expression of CYP2A6 and CYP2A13 was also determined by using immunoblot analysis with arrowheads (Y) pointing to the corresponding bands of CYP2As.