Based on the dye cresyl violet and the cathepsin L PheArg peptide recognition sequence, this kit allows the detection of cathepsin L activity in living cells by fluorescence microscopy.

Once cells are grown, staining is completed in just a few minutes. Hoechst 33342 stain and Acridine Orange are also included to allow visualization of nuclei and lysosomes.

Elevated cathepsin enzyme activity often indicates the presence of a pathological condition including cancer, Alzheimer's disease, autoimmune disease, and osteoporosis.