In particular, expression of the GlcNAc transferases GcNT3 (one of the GlcNAcTs responsible for the synthesis of the core 2 O-glycan structures) and B3GNT3 (responsible for the synthesis of the extended core 1 O-glycan structure) were found to be markedly increased in the adenocarcinoma tissues. This evidence concerns the gene GCNT3 and adenocarcinoma.