Arterivirus nsp1 and N proteins also localize in the cytoplasm and the nucleus of infected cells. Porcine reproductive and respiratory syndromevirus (PRRSV) N protein accumulates in the nucleoli of infected cells, where it interacts with the host cells proteins fibrillarin, nucleolin, and poly(A)-binding protein (PABP), the latter of which is transported to the nucleus during infection. PRRSV N protein also activates the NF-κβ-mediated pathway in the cytoplasm. The nsp1β subunit of nsp1 suppresses the JAK-STAT pathway and also interacts with protein inhibitor of activated STAT1(PIAS1). Because PIAS1 is a nuclear protein which multiple functions, its interaction with nsp1 may lead to the modulation of several host cell pathways.