passages.id: split_6_test_3387_passage
passages.type: progene_text
passages.text: The presence of dsRNA during viral infections is a key step in activation of several signaling pathways , including protein kinase R ( PKR ) , toll - like receptor 3 ( TLR3 ) , mitogen - activated protein kinase ( MAPK ) , activator protein-1 ( AP-1 ) , interferon regulatory factors ( IRFs ) , and NF-kappaB pathways , which are all relevant in the expression of inflammatory cytokines .