STING stimulation in T cells inhibits cell cycle progression. STING stimulation in T cells inhibits cell cycle progression. (A, B) FACS-sorted naive CD4+ T cells from Sting+/+ or Sting−/− mice were stimulated with immobilized anti-CD3ε plus anti-CD28 (anti-CD3/CD28) Abs with or without STING ligands cGAMP or DMXAA. Cell growth was assessed after 48 h of stimulation by a WST-8 proliferation assay (A), and cell survival was determined after 18 h of stimulation by Propidium iodide (PI) and Annexin V staining (B). (C) Naive CD4+ T cells from Sting+/+ or Sting−/− mice were stimulated with cGAMP or DMXAA for 18 h, and cell survival was determined by PI and Annexin V staining. (D, E) Naive CD4+ T cells were stimulated with anti-CD3/CD28 Abs with or without cGAMP for 48 h, and cell division was determined by a CFSE-labeling assay (D) and cell cycle was assessed by PI staining (E). (F) Western blot analysis for protein expression of cell cycle–related genes in CD4+ T cells upon stimulation with anti-CD3/CD28 Abs with or without cGAMP for 24 h. Data are the mean from duplicate (A–C) ± SD. Data are representative of at least three independent experiments. (A–F) *P < 0.05, t test (compared with WT cells treated with indicated ligands). Takayuki Imanishi et al. LSA 2019;2:e201800282 © 2019 Imanishi et al.