Fig. 1

Effects of polycyclic aromatic hydrocarbons (PAHs) on HPV16E7-transfected baby rat kidney (BRK) cells. Cells transfected with pcDNA16E7 and pEJ6.6 were selected by 220 μg/mL of G418 in the presence of 1 μM of PAHs. Cells were fixed and stained on day 18 post-transfection. Transformed BRK cell colonies were divided into three size groups: small (< 6 mm²), assigned 1 point; medium (6–20 mm²), assigned 4 points; and large (> 20 mm²), assigned 8 points. The transformation score of each PAH was then calculated by the formula: number of small colonies × 1 + number of medium colonies × 4 + number of large colonies × 8. Co-transforming ability of PAH and HPV was represented by colony formation index (CFI = PAH transformation score / negative control transformation score). Data are the mean ± SEM values obtained from triplicate culture dishes per group from three independent experiments. Significant level: *p < 0.05, **p < 0.01, ***p < 0.001