"TAT-BH4 (Bcl-xL) TFA, primarily localized at the mitochondria, inhibits apoptotic cell death. This compound comprises an eosin-labeled cysteine at the N-terminal and the protein transduction domain from the HIV TAT protein (amino acids 49 to 57), fused to the Bcl-xL BH4 peptide. It is utilized in research concerning diseases associated with accelerated apoptosis [1]."