Importantly, more than 97% reduction of endogenous levels of LEDGF/p75 was also observed in both TL3 LEDGF/p75 WT and TL3 LEDGF/p75 ΔPWWP cells, supporting the notion that the susceptibility of TL3 LEDGF/p75 ΔPWWP cells to HIV-1 infection was not determined by the existence of functional amounts of endogenous LEDGF/p75. Here, PSIP1 is linked to HIV-1 infection.