FLIP also known as CFLAR is a regulator of apoptosis and is structurally similar to caspase-8. FLIP exists in both long and short forms, plays a crucial role in the regulation of apoptosis, a vital process for maintaining cellular homeostasis and preventing uncontrolled cell proliferation. The short form of FLIP features two death effector domains that are homologous to those found in the FAS-associating protein FADD, while the long form shares significant homology with the cysteine protease FLICE and includes an additional caspase-like domain. The long form lacks a catalytic active site and the necessary residues for substrate binding, which distinguishes FLIP from typical caspases.