PSIP1 and HIV-1 infection: We previously showed that the HIV-1 integration cofactor LEDGF/p75 surrounds nuclear speckles containing CPSF5 and CPSF6 upon HIV-1 infection5; therefore, we tested whether CPSF6 was required for this process to occur and found that LEDGF/p75 does not surround nuclear speckles upon HIV-1 infection in CPSF6-KO cells (Fig. 5Diii and iv).