OGT and colorectal carcinoma: Furthermore, reduced levels of OGT and OGA might not normally regulate dynamic O-GlcNAcylation during the cell cycle, which is required for cell cycle control.15, 16 We conclude that O-GlcNAc enzymes are essential for tumor growth in CRC, and that targeting OGA may help suppress the intestinal tumorigenesis initiated by Apc mutation.