Double-stranded RNA-activated protein kinase (PKR), a serine/threonine kinase, is activated in virus-infected cells and acts as an antiviral machinery of type I interferons. PKR controls several stress response pathways induced by double-stranded RNA, tumor necrosis factor-aor lipo-polysaccharide, which result in the activation of stress-acti-vated protein kinase/c-Jun NH2 -terminal kinase and p38 of the mitogen-activated protein kinase family.