Enzyme based cytotoxicity assay using MTT and WST dyes rely on a reductive coloring reagent and dehydrogenase in a viable cell to determine the cell viability. Therefore, even if the result shows cytotoxicity, it is difficult to say whether the dehydrogenase activity of the cells is lowered or it is due to the cell membrane damage. In recent years, as another indicator LDH is measured as a supporting data of cytotoxicity. Learn more about cell proliferation/cytotoxicity assay here.
Here is the list of some articles which utilizes multiple methods to increase the data reliability: