Final answer:
In the extrinsic pathway of apoptosis, the cytolytic tails of three Fas receptors recruit FADD proteins, initiating a cascade that leads to cell death.
Step-by-step explanation:
In the extrinsic pathway to apoptosis, the cytolytic tails of three Fas receptors recruit three adapter proteins known as Fas-associated death domain (FADD) proteins. The interaction between the Fas receptor, a type of death receptor, and its FADD proteins is crucial in transmitting apoptotic signals. The Fas ligand molecule, which is expressed on cytotoxic T cells and NK cells, binds to the Fas molecule on a target cell and induces it to undergo apoptosis. This event is part of a complex cascade of interactions that leads to cell death, ensuring the removal of unwanted or damaged cells as a critical function in maintaining the health of an organism.