CPSF6 and HIV-1 infection: Further evidence for a link between CPSF6 and TNPO3 include data showing that mutants of TNPO3 that are selectively impaired for interaction with CPSF6 do not support HIV-1 infection [24], whilst TNPO3-depleted cells are refractory to wild-type HIV-1 infection only in the presence of endogenous CPSF6 [25].