In contrast to natural anti-MUC1 IgG antibodies from breast cancer patients that react more strongly with glycosylated than with naked MUC1 peptides, the induced antibodies tested in ELISA against defined GalNAc-MUC1 glycopeptides showed progressively diminishing reactivity with increasing glycosylation of the peptide [81]. The gene discussed is MUC1; the disease is breast cancer.