BCL2 and cancer: In particular, the role of the BH3 domain in isolation (i.e., outside the context of the full-length protein) as the mediator of the death signal is of significance to clinical research, as this interaction site has become an attractive drug target in the treatment of cancer.18, 19 The interactions of the BH3 peptides with the anti-apoptotic and pro-apoptotic-effector Bcl-2 proteins have been studied thoroughly in vitro, however, the BH3-only proteins are not easily express recombinantly,12 making it difficult to derive reliable conclusions from peptide-based interaction studies.