CGAS and Autoimmunity: A competitive inhibitor that binds to the nucleotide binding site of cGAS and inhibits cGAS activity, PF-06928215, was identified in an in vitro assay screen for cGAS inhibitors [350], while the small molecules RU521 and RU365 inhibit the catalytic activity of cGAS in the macrophages of genetically engineered autoimmune mice [351].