TAT and HIV-associated neurocognitive disorder: Like Tat, gp120 expression is used to model HAND in transgenic rodent models; however, it is important to note that the majority of the gp120 studies that met the criteria for this review primarily focused on the combined effects of gp120 expression and meth exposure on neuroimmune and behavioral functioning, with limited characterization of the effects of gp120+/Cocaine+.