ZNF639 and infection: In striking contrast to the results obtained from infection by a full HIV-1 vector (Fig. 2A), the basal activity of the HIV-1 mZBS promoter in this plasmid context was not significantly different from the WT promoter, and neither WT nor the mZBS promoter was stimulated by co-transfecting a ZASC1 expression plasmid (Fig. 5A).