STING1 and infection: Analysis of the pure cytosolic extracts demonstrated that wild-type (WT) influenza A virus significantly induced mtDNA release in HEK293FT cells (Fig. 1b, c), A549 cells stably expressing the STING protein (termed STING-A549 cells), and mouse lung fibroblasts (Supplementary Fig. 2) in a multiplicity of infection (MOI)-dependent manner within 24 h post infection.