To test this, the wild-type vector (WTVector), KOVector, and complemented CEM and MT-4 cells were infected with vesicular stomatitis virus G protein (VSVg)-pseudotyped HIV-1 expressing green fluorescent protein (GFP) from the nef position (HIV-GFPVSVg), and the extent of infection was scored by flow cytometry. Here, PROS1 is linked to infection.