Cell Biolabs’ CytoSelect™ LDH Cytotoxicity Assay Kit provides a colorimetric format for measuring and monitoring cell cytotoxicity. The kit contains sufficient reagents for the evaluation of 960 assays in 96-well plates. Cells can be plated and then treated with compounds or agents that affect cell viability. Upon cell death, lactate dehydrogenase (LDH), a soluble enzyme found in the cytoplasm, is released into the growth media. The growth media is then transferred to another plate and the released LDH is then detected with cytotoxicity reagent. In the presence of lactate substrate (included in the LDH Cytotoxicity Reagent) LDH converts lactate to pyruvate and generates nicotinamide adenine dinucleotide (NADH). The WST-1 molecule, also present in the LDH Cytotoxicity Reagent, is converted from WST-1 to the orange formazan form. An increase in cell cytotoxicity is accompanied by increased LDH release and increased colorimetric signal. The assay principles are basic and can be applied to most eukaryotic cell lines, including adherent and non-adherent cells and certain tissues, depending on LDH expression levels.