r8 Bid BH3, a biologically active peptide, is a pro-apoptotic member of the "BH3-only" subset within the BCL-2 family proteins, pivotal in regulating apoptosis. This compound exhibits lethality towards Bcl-2-expressing human leukemia cell lines, indicating its promise as a potential cancer therapeutic. The peptide is conjugated with poly-D-arginine (denoted by rrrrrrrr), enhancing cellular uptake.