The extracellular death stimuli, such as the Fas ligand, directly activate the death receptors through ligand-induced assembly of a death-inducing signaling complex (DISC) at the plasma membrane (Nagata 1999, Peter & Krammer 2003) (Figure 1). An adapter protein, Fas-associated death domain (FADD), appears to be the obligate factor, which recruits the initiator caspase, procaspase-8 or -10, to DISC for activation. The activated caspase-8 subsequently cleaves and activates caspase-3 and -7. Thus extrinsic and intrinsic cell deaths converge at the point of caspase-3 or -7 activation. An important physiological target of the activated caspase-8 is Bid, a BH3-only member of the Bcl-2 family of proteins. After cleavage, the C-terminal fragment of Bid (truncated Bid or tBid) translocates to the outer membrane of mitochondria and induces the release of proapoptotic factors (Li et al. 1998, Luo et al. 1998). Thus Bid mediates the crosstalk from the extrinsic to intrinsic form of cell death.