In this example, K562 cells were exposed to Methotrexate, an anti-proliferative compound, for 72 hours. CellTox™ Green Dye was added to determine cytotoxicity, then CellTiter-Glo® Reagent was added to the same sample well for viability determination. A viability assay alone would have misreported the compound as cytotoxic due to less cells in the treated sample compared to the non-treated control, which continued to proliferate. Multiplexing with a cytotoxicity assay reveals no change in signal as a result of compromised membrane integrity, indicating growth inhibition and not cytotoxicity.