RIGI and cystic fibrosis: Remarkably, when pro-inflammatory cytokines measured at the protein level in supernatants of PolyIC-stimulated CF without transfection, whereby membrane-bound TLR3 was activated, were compared to PolyIC-transfected CF, whereby cytosolic MDA5 and RIG-I were activated, the latter produced significantly higher amounts of IL-6, IL-8 and TNF-α (Fig. 4b).