Figure 2. Comet assay confirms DNA single-strand breaks induced by tobacco-related compounds. (A) Dose-dependent increase in comet tail moment with increasing smokeless tobacco extract. Each entity represents 1 POII cell. POII tail moment increases with increasing concentrations of smokeless tobacco extract (B), NNN and NNK (C), and nicotine (D). Each point is the mean ± standard error of 25 individual cells.