SARS-CoV proteins 6 and 9b affect nucleocytoplasmic transport. Protein 6 impedes nuclear import of factors such as STAT1  and antagonizes IFN signaling pathways. Protein 9b shuttles from the nucleus by its interaction with cellular exportin 1 (Crm1), which is essential for proper protein 9b degradation, and blocking nuclear export of protein 9b induces cell apoptosis.