Figure 1.

Mutagenesis/carcinogenesis paradigm with benzo[a]pyrene. Steps in the horizontal direction lead toward carcinogenicity, and include metabolic activation (step 1), reaction with DNA (step 2), adduct mutagenesis (step 3), and tumorigenesis (step 4). Steps in the vertical direction lead to diminished carcinogenicity, and include metabolic detoxification (step 5), carcinogen deactivation (step 6), and DNA repair (step 7). Diminished carcinogenicity is also associated with other cellular processes, such as delaying the cell cycle and apoptosis [1].