ICT’s FLISP® serine protease assays enable researchers to detect intracellular chymotrypsin-like serine protease activity in vitro without lysing the cell. FLISP (Fluorescent Labeled Inhibitors of Serine Proteases) reagents are cell-permeant, non cytotoxic green or red fluorescent inhibitors that covalently bind with active serine protease enzymes.