Z-VAD-FMK is widely used in biomedical research as a potent and irreversible caspase inhibitor. It plays a crucial role in studying apoptosis, or programmed cell death, by effectively blocking the activity of caspases, which are key enzymes in the apoptotic pathway. This makes it a valuable tool for investigating the mechanisms of cell death in various contexts, such as cancer, neurodegenerative diseases, and immune responses. Researchers often use Z-VAD-FMK to determine whether cell death observed in experiments is due to apoptosis or other pathways, such as necrosis. Additionally, it is employed in studies exploring the protective effects of inhibiting apoptosis in conditions like ischemic injury or organ transplantation. Its ability to permeate cell membranes further enhances its utility in both in vitro and in vivo experimental models.