Determination of Cell Viability

The MTT colorimetric assay was performed to ensure that non-toxic concentrations of U0126, BAY-11-7082, BAY-11-7085, and ATA were used. Cells were incubated for 24 h with the test compounds diluted in a cell-type specific medium. After that, cells were incubated with MTT solution (5 mg/mL in medium) for 2 h. The supernatant was discarded, and cells were lysed in 100 μL DMSO. Absorbance measurements were carried out at 550 nm with 630 nm as the reference wavelength using a microplate reader (Tecan Sunrise). The cell viability obtained from at least two independent experiments was calculated relative to untreated and solvent controls (data not shown).