In order to assess in vivo the biological relevance of GnT-V-mediated N-glycosylation/ O-mannosylation interplay we analyzed the expression of β1,6 GlcNAc branched N-glycans and O-mannosylated proteins in stomach paraffin samples from MGAT5 transgenic mice models and human gastric carcinomas clinical samples. This evidence concerns the gene MGAT5 and gastric carcinoma.