Stimulator of interferon genes (STING) induces production of type I interferon when cells are infected by viruses, mycobacteria and intracellular parasites. STING recognizes and binds cyclic-di-GMP produced by bacteria and cyclic-GMP AMP (cGAMP) produced by viruses. The C-terminal domain (CTD) (residues 139-379 in human) of STING binds cyclic-di-GMP. STING is a facilitator of innate immune signaling.