STAT1 and influenza: Supplementary Figure 7A verifies that IRF1 expression is abolished constitutively or upon IFNβ treatment in the KO cell lines. Similar to the BEAS-2B cells, A549 cells also showed reduced level of STAT-1 phosphorylation in response to poly I:C stimulation (Supplementary Figure 7B), reduced level of constitutive MX1 expression and increased susceptibility to Influenza infection compared to the parent A549 cells (Supplementary Figures 7C–E).