Used as a chromogenic substrate in caspase activity assays, particularly for detecting caspase-3 and caspase-7 activity. The presence of the p-nitroanilide group allows for colorimetric detection upon cleavage by the target caspase, producing a yellow-colored product that can be measured spectrophotometrically at 405 nm. This makes it valuable in apoptosis research, drug screening, and biochemical studies where quantification of caspase activation is required. Its tetrapeptide sequence (Ile-Glu-Pro-Asp) is specifically recognized by effector caspases, ensuring high selectivity. Commonly used in cell lysates, enzyme kinetics, and high-throughput assays to monitor programmed cell death.