However, a glycoform of MUC21 with extended carbohydrate chains was found in suprabasal cells and serves as a marker for differentiation in squamous cell carcinoma (30), indicating a potential role of MUC21 O-glycosylation in esophageal differentiation, which would be consistent with Reactome pathway predictions (Figure 4D). Here, MUC21 is linked to squamous cell carcinoma.