Figure 3. ATO combined with IR inhibits the clonogenic survival of SCCHN cells in an additive manner.

Cells were seeded at a density of 300/well in 12-well plates. Twenty four hours after seeding, cells were left untreated or were treated with the indicated doses of ATO, IR or the combination of both. Non-irradiated cultures were processed along with irradiated cultures. Cells were incubated for up to 14 days. Survival fractions for given treatments were calculated on the basis of survival of non-treated cells and corrected for the effect of ATO alone. Each sample was done in triplicate. Mean values from at least three independent experiments are presented. The symbols for the different treatments are given in the top of the figure. The p53 genotype of each individual cell line is depicted in the graphs.