Cell cycle traverse in cancer cell lines exposed to MF. Cells were exposed to vehicle or the indicated concentrations of MF for 72 h, harvested, and stained with propidium iodide. DNA content was analyzed by microcytometry. Bars represent the mean ± s.e.m. of at least 3 independent experiments completed in triplicate, and show the percentage of cell particles with G0/G1 (A, D), S (B, E) and G2/M (C, F) DNA content. *P < 0.05, **P < 0.01, ***P < 0.001 denote differences as compared to controls.