G2/M cells percentage. Cells percentage was assessed by cell cycle analysis of BEAS-2B cells exposed for 3 h to 7.5 μg/cm2 of whole-PM and organic fraction. NAC and α-NF were used to determine the role of ROS and CYP enzymes, respectively. * Statistically significant difference from control, P < 0.05. The results are representative of 3 independent experiments.