STING (Stimulator of Interferon Genes) is a transmembrane protein localized to the endoplasmic reticulum that undergoes a conformational change in response to direct binding of cyclic dinucleotides (CDNs), resulting in a downstream signaling cascade involving TBK1 activation, IRF-3 phosphorylation, and production of IFN-β and other cytokines.

STING is a pattern recognition receptor of cyclic dinucleotides as well as an innate immune adaptor protein that enables signaling from cytoplasmic receptors to the transcription factor interferon regulatory factor 3. Initiation of these pathways leads to the expression of type I interferons and proteins associated with antiviral and antitumor immunity. Small molecules capable of triggering STING-dependent cellular processes are effective at blocking virus replication, enhancing vaccine efficacy, and facilitating immune response to cancer cells.