Figure 1

TRAIL or FasL treatment of LN18 cells provokes generation of 6-TG-resistant colonies. LN18 cells were incubated with various doses of ethane methyl sulfonate (a), cisplatin (b), cross-linked TRAIL (c), soluble TRAIL (d) or Fas ligand (e), either for 24 h or for 1 h followed by 23 h incubation in normal media. Propidium iodide uptake (a–d) or clonogenicity assays (a–e) were then performed, as outlined in the Materials and methods. Cells were exposed to selected doses of the drugs for 1 h for HPRT mutagenicity assays. The left Y-axis and black and gray lines depict survival as measured in acute cell death and clonogenicity assays. The right Y-axis and white columns show the number of 6-TG-resistant colonies in mutational assays. Error bars indicate standard errors of the means from either three (a, b, e), four (c) or five (d) independent experiments.