These results suggest that the Nup93 subcomplex is a key regulator of the functional interaction between the HIV-1 CA and the nuclear pore complex, and that variation in the composition of this complex among cell types or during the cell cycle could underlie several of the discrepant effects of CA mutations, CypA, and MX2 on HIV-1 infection. The gene discussed is PPIA; the disease is HIV-1 infection.