The role of PKR in antiviral responses. dsRNA molecules derived from RNA viruses and different forms of cellular stress can induce PKR dimerization and autophosphorylation. PKR contributes to the antiviral responses at many levels: (1) It recruits and phosphorylates eIF2a, resulting in inhibition of viral protein synthesis and apoptosis; (2) PKR enhances type 1 IFN production by interaction with IRF3 and NF-kB pathways; (3) PKR regulates actin dynamics and abrogates viral entry into cells by inhibiting gelsolin; and (4) PKR physically interacts with inflammasome components or RIP1 and promotes pyroptosis and necroptosis. dsRNA, double-stranded RNA; IFN, interferons; IRF, interferon response factor; NF-kB, nuclear factor-kappa B; RIP, receptor-interacting protein. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars