v-FLIPs are viral proteins that were first identified as modulators of apoptosis; they contain two death effector domains, which are also found in some initiator caspases such as procaspase-8. These v-FLIP proteins can be recruited to the DISC through the binding of the death effector domain to similar domains in the adaptor proteins but are otherwise catalytically inactive. What do you think is the effect of v-FLIP expression in the host cell?A. It promotes apoptosis mainly via the extrinsic pathway.B. It inhibits the extrinsic pathway of apoptosis.C. It activates only the mitochondrial pathway of apoptosis.D. It inhibits the intrinsic pathway of apoptosis.E. It enhances the caspase cascades in both the intrinsic and extrinsic pathways.

Apoptosis is a cellular pathway that leads to programmed cell death. Viral FLICE-inhibitory proteins (FLIPs) bind to the adaptor proteins and block the interaction between the DISC complex with the caspase-8 protease enzyme, which triggers apoptotic cell death. In consequence, cells become resistant to Fas-mediated apoptosis, a pathway initiated by the FADD protein which is known to recruit caspase-8.