The coronavirus protein most frequently associated with the host cell nucleus  is the N protein, and its transport to the nucleus is regulated by phosphorylation. N protein nuclear localization is associated with induction of cell cycle arrest and inhibition of cytokinesis and is involved in recruitment to the cytoplasm of cell nuclear proteins, such as heterogenous nuclear ribonucleoprotein A1 (hnRNP A1) and the helicase DDX1.