Figure 3.

Quantitative real time PCR results for select genes across never, former, and current smokers. For each graph sample identifiers for never (orange), former (purple), and current (green) smokers are listed along the x-axis. The sample identifications P1, P2, and P3 refer to three samples collected prospectively from never smokers that do not have corresponding microarrays. The months since smoking cessation are listed below each former smoker. The relative expression level on the y-axis is the ratio of the expression level of a particular sample versus that of a dummy reference sample. (a) Plots of two rapidly reversible genes, CYP1B1 and ALDH3A1. (b) Plots of two irreversible genes, CEACAM5 and NQO1.