Figure 2. Synergistic combinatorial drug pairs on lung cancer cells.

(A, B) Effects of alsterpaullone, scriptaid, irinotecan, and semustine on A549 cancer cell proliferation. IC₅₀ indicates the concentration of drug that induce 50% of inhibition of cell proliferation. Error bars represent the standard deviation of six experiments. (C, D) Drug pairs were treated in 1∶1 molar ratio. The IC₅₀ values of each drug are plotted on the axes, and the dashed line represents addictive effect. Triangle point represents the concentrations of the combinations resulting in 50% of proliferation inhibition. As the triangle points are positioned on the left of the dashed line, these combinatorial drug pairs are synergistic. The IC₅₀ values of each drug in alsterpaullone-scriptaid and irinotecan-semustine combinations are 0.65 µM and 26.05 µM, respectively.