The activation of JNK upon viral-RNA transfection is RIG-I dependent. A549 cells were transfected with siRNA targeting RIG-I (siRig) or Mda5 (siMda5). Subsequently, the cells were transfected with viral RNA or cellular RNA, harvested after 4 h, and analyzed by Western blotting. sictr, control siRNA; nt, not transfected with siRNA.