Figure 4.

Effects of RBC-2008 on the human tumor cell viability in CellTiter-Glo^® assay. Approximately 1,000 of U266 cells, REH cells, K562 cells, KMS-11 cells, RPMI-8226 cells, and MM.1S cells were incubated with the indicated concentrations of RBC-2008 in 384-well assay plates at 37°C, 5% CO₂ for 72 h. Then, 25 µL of CellTiter-Glo^® reagent was added to the wells of the assay plates and incubated at a room temperature for 10 min with gentle shaking. The luminescent signal within plates were measured by using EnVision Multilabel Reader. The IC₅₀ curves were plotted, and the IC₅₀ values were calculated by using the GraphPad Prism 4 program based on sigmoidal dose–response equation. The IC₅₀ values of RBC-2008 were calculated to be 14.5 µM, 1.8 µM, 13.1 µM, 2.5 µM, 3.8 µM, and 2.1 µM on U266 cells, REH cells, K562 cells, KMS-11 cells, RPMI-8226 cells, and MM.1S cells, respectively. Data shown here represent one of three independent experiments.

Abbreviation: IC₅₀, half maximal inhibitory concentration.