4.3. MTT Assay for Cell Viability

An MTT assay was performed to determine the cytotoxicity of tivantinib and other chemotherapeutic agents in the cancer cells, as previously described [41]. Briefly, 5000 cells were seeded evenly into 96-well plates and incubated for 24 h. On the second day, serial dilutions of the substrate drugs were added to the designated wells with or without the presence of reversal agents. The cells were then incubated for 72 h. On the last day, an MTT solution was added and further incubated for 4 h at 37 °C. After incubation, the supernatant was discarded, and 100 μL of DMSO was added to dissolve the formazan crystal. The light absorbance was measured at 570 nm using an accuSkanTM GO UV/Vis Microplate Spectrophotometer (Fisher Sci., Fair Lawn, NJ, USA). The IC₅₀ value and resistance-fold (RF) were calculated as described previously [42].