Cayman's Lysosome/Cytotoxicity Dual Staining Kit is a tool for studying lysosome function at the cellular level. The kit employs 4-nitro-7-(1-piperazinyl)-2,1,3-benzoxadiazole (NBD-PZ), which is membrane permeable and reacts with carboxylic acids in the acidic luminal environment of lysosomes, as a probe for the detection of lysosomes in cultured cells. Propidium iodide is used as a marker of cell death. Chloroquine, a known inhibitor of lysosome function, is included as a positive control. The kit provides sufficient reagents to effectively treat/stain up to 10 plates worth of cells irrespective of the number of wells/plate.