TAT and infection: Intracellular staining for Tat on samples obtained 24 and 48 hrs after Ad-TatSF2 infection ranged between 40 and 60 percent positive cells (data not shown) and was found both in the cytoplasm and in the nucleus in the case of the wild type and the mutants excepts for TatSF2G48-R57A, with was detected virtually exclusively in the cytoplasm (Figure 1C).