Interestingly, under stringent condition in the presence of our lysis buffer containing 1% Triton X-100, DHX29 did not interact with LGP2 or RIG-I, even after various kinds of stimulations. But in much lesser stringent condition such as in the presence of cell lysis buffer containing 0.1% NP-40 which was used in a recent report , we detected some weak association (S5G and S5H Fig). These results suggest that DHX29 specifically interacts with MDA5, but not with RIG-I or LGP2 protein, in a stringent condition which is optimal for determining the association in CO-IP assay. We further assessed the relative contribution of LGP2 and DHX29 to MDA5-mediated type I IFN signaling by knocking down or overexpression approaches. We found that KD of DHX29 markedly reduced IFN-β-luc activity induced by HMW Poly(I:C), which could be partially restored when LGP2 was overexpressed. Similarly, LGP2 KD strikingly reduced IFN-β-luc activity induced by HMW Poly(I:C), which could be partially restored when DHX29 was overexpressed (S5I Fig). Ectopic expression of both LGP2 and DHX29 further enhanced IFN-β-luc activity. Conversely, KD of LGP2 and DHX29 further markedly reduced IFN-β-luc activity (S5I Fig). These results suggest that LGP2 and DHX29 have additive and independent effects on MDA5-mediated type I IFN signaling pathway. Therefore, DHX29 enhances MDA5-mediated type I IFN signaling, independent of LGP2.