Tat can also be found as a surface-bound or an extracellular protein with an arginine–glycine–aspartic acid (RGD) integrin-binding motif encoded by a second exon, which does not contribute to the transcriptional activities of Tat but can contribute to neurological and vascular manifestations of HIV-1 infection [73,74,75,76]. Here, TAT is linked to HIV-1 infection.