a-b, ISG expression in Tfam+/− MEFs transfected with the indicated siRNAs (top panels), or WT, cGas−/− (a), and Sting−/− (b) MEFs transfected with TFAM siRNAs (bottom panels). c-d, ISG expression in Tfam+/− MEFs transfected with the indicated siRNAs for 96 hrs. e, Western blots of whole cell and nuclear extracts of WT and Tfam+/− MEFs or Tfam flox ERCre−/+ BMDM exposed to 4OHT for 96 hrs. f-gcGAS−/− MEFs reconstituted with cGAS-HA were transfected with the indicated siRNAs for 96 hrs, then stained with anti-DNA, anti-Hsp60 [Mito], and anti-HA antibodies and imaged. cGAS colocalization scoring was performed as described in the Methods. Error bars indicate ± s.e.m. of triplicates and are representative of three independent experiments. *=p<0.05, **=p<0.01, ***=p<0.001.