Taken together, these results show that XIAP is an E3 ubiquitin ligase of OGT, is modified by O-GlcNAc at serine 406, and this modification on XIAP leads to the polyubiquitination and degradation of OGT, resulting in the inhibition of colon cancer cell growth and invasion (Fig. 6). The gene discussed is XIAP; the disease is colonic neoplasm.