Fig 1: PDS triggers the activation of the cGAS–STING signaling pathway. (A) IF images of cGAS-bound micronuclei in MCF-7 cells treated with 10 µM PDS (left) and cGAS-positive micronuclei levels in untreated and PDS-treated cells (right). Data show means of three biological replicates. Significance was determined with a multiple paired t-test: **P-value <0.01. (B) Levels of cGAMP dinucleotide over time in untreated and PDS-treated MCF-7 cancer cells. cGAMP levels were determined using the Direct 2',3'-Cyclic GAMP Enzyme Immunoassay Kit. Data show means ± SEM of at least three biological replicates. The P-value (determined with the Mann–Whitney test) is 0.057 at day 4. (C) IF image of STING in MCF-7 cancer cells as indicated [H151 (2µM) is a STING inhibitor]. (D) IF images of IRF3 and pIRF3 (phosphorylated Ser396 IRF3) in MCF-7 cancer cells as indicated. ssDNA indicates cells transfected with salmon sperm DNA as a positive control. (E) Fraction of pIRF3-positive (>2 nuclear foci) MCF-7 cells at day 4. Data show means ± SEM of two biological replicates. Significance was calculated by the chi-square test: ****P-value <0.0001. Scale bar is 10 µm.