Schematic representation of the caspase activation cascade that leads to the cleavage of Bcl-xL and its requirement for uptake by recipient cells. Activation of an DR or a TLR on the exosomal surface may lead to the processing and activation of caspase-8 and the downstream effector caspase-3/7. Caspase-3/7 cleaves the exosomal Bcl-xL, which assumes a membrane-bound conformation on the surface of the exosomes promoting the uptake of exosomes by recipient cells. The interaction of the exosomal Bcl-xL with the recipient cells may be mediated by a direct protein–protein interaction with an, at present, unknown receptor. casp-3, caspase-3.