Figure 4.

Cell viability assay (a) showing enhanced toxicity of 72 h exposure to 20nM 5-aza (~IC₅₀) plus 72 h off treatment among all cell lines, 2102Ep/-R and NCCIT/-R (b,c). A significant sensitization towards a regular dose of cisplatin by adding a low dose of 5-aza (10 nM) was achieved in both resistant sublines by either immediate or delayed sequential treatment decreasing viability by 13–18%. This effect was less clear and not significant in the sensitive cell lines. Shown are mean and SD of a single triplicate experiment. Each experiment was conducted at least three times with similar results. CDDP, Cisplatin; ∆, numeric difference between relative viabilities (%).