Epigenetic silencing of glycosyltransferase genes necessary for the synthesis of more complex O-glycan core structures may, for instance, be involved, for some of related enzymatic activities are known to be significantly decreased in cancers (20, 46) Down regulation of the genes encoding core 1 enzyme and/or its chaperon Cosmc may also lead to the appearance of Tn and sialyl Tn antigens (47, 48). Here, C1GALT1C1 is linked to cancer.