Cationic cell-penetrating peptides (CPPs) have been used widely as delivery vectors for the import of molecules that otherwise do not cross the plasma membrane of eukaryotic cells. These peptides have been used as vectors for the delivery of hydrophilic drugs to the cell nucleus, as well as delivering oligonucleotides for possible gene therapy applications. This peptide is an eleven amino acid cell permeable human immunodeficiency virus transactivating regulatory protein (TAT) domain, cell permeable, labeled with TAMRA, Abs/Em=544/572 nm.