NUDT21 and infection: To determine whether the increased SLFN5 expression observed in HIV-1–infected cells correlates with CPSF5 and CPSF6 translocation to nuclear speckles, we analyzed SLFN5 expression in human cells infected with HIV-1 in the presence of the small molecule PF74, which prevents CPSF5 and CPSF6 translocation to nuclear speckles during infection (52).