GCG and cancer: In non-cancer-related events, the interplay between calcium signalling and O-GlcNAcylation has earlier been reported in glucagon-stimulated liver autophagy and metabolic adaptation.46 That is, glucagon induces Ca2+ release via an intracellular Ca2+ channel InsP3R1 and activates CaMKII, of which phosphorylates OGT and promotes O-GlcNAcylation and activation of Ulk1, a key regulator in autophagy initiation.