CD274 and cancer: PD-L1 is exclusively N-glycosylated at N35, N192, N200 and N219 residues in cancer cells and those modifications have been demonstrated to stabilize the protein, preventing its interaction with glycogensynthase kinase 3β (GSK3β) and thus protecting PD-L1 from phosphorylation-dependent proteasome degradation (Li et al., 2016).