The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is an anti-viral pattern recognition pathway. In Drosophila, cyclic GMP-AMP (cGAMP) synthases are activated by viral infection, cGAMP is in turn detected by STING ultimately resulting in the activation the NF-κB-like factor Rel and its translocation into the nucleus to activate the transcription of anti-viral genes. (Adapted from FBrf0252868.)