Used as a fluorescent probe for labeling biomolecules such as proteins and antibodies due to its ability to form stable amide bonds with primary amines. The compound readily crosses cell membranes, where intracellular esterases cleave the acetate groups, trapping the fluorescent product inside live cells. This makes it valuable for cell tracking, viability assays, and monitoring cell proliferation in flow cytometry and fluorescence microscopy. Also applied in studying cell migration and fusion in immunology and developmental biology.