Changes of the cell-surface protein glycosylation together with MUC1 protein overexpression, results in the formation of tumor-specific epitopes consisting of both the formed short saccharides, e.g., TN, T, sialyl-TN and sialyl-T, and the mucin tandem repeat peptide region, which is exposed due to the aberrant glycosylation (Figure 1) [25–27]. The gene discussed is MUC5AC; the disease is neoplasm.