CGAS and cancer: Cancer cells activate the cGAS–STING (stimulator of interferon genes) pathway in astrocytes by transfer of 2′,3′-cyclic GMP-AMP (cGAMP) through gap junctions and thereby promote the production of inflammatory cytokines such as interferon-α (IFN-α) and tumor necrosis factor–α (TNF-α) by the astrocytes (Fig. 1a(f)).