BJ WT and cGAS KO cells were harvested by trypsinization, centrifuged, and rinsed once with ice-cold PBS. To- tal RNA was extracted using the PureLink RNA Mini Kit (Invitrogen), according to the manufacturer's instructions. RNAs isolated from all fibroblast lines (1 ug per sample) were reverse-transcribed to generate sequencing libraries using the TruSeq Stranded Total RNA Library Prep Kit (Illumina) and sequenced by HiSeq2000 (Illumina) (Novogene Corporation, 8801 Folsom Blvd., Suite 290, Sacramento, CA). Approximately 27 million to 39 million sequencing reads were generated for each fibroblast mRNA preparation, and 81 to 94% of fragments were mapped by both ends to the human genome (hg19) using TopHat (version 2.0.7) and bowtie2 (version 2.1.0).

GFP-U2OS cells treated with or without H₂O₂ for 24h were collected. Lysates were cleared by centrifugation at 13,000 rpm for 15 min and incubated with G-Sepharose protein beads (GE Healthcare Bio-Sciences) attached with and without GFP antibody overnight at
4°C on a rocking platform. Beads were then collected by centrifugation at 8200 rpm for 5 s at 4°C, extensively washed in lysis buffer, and resuspended in SDS gel loading buffer. The proteins were separated on a 10% SDS–polyacrylamide gel then for the sequence.