CPD and cancer: Investigation of the identified sialoglycoproteins using previous reported glycoproteins showed that among the 55 identified sialoglycoproteins labeled by sialic acid analog, 42 proteins have documented correlation with cancer (Additional file 2: Table S2), including the 4F2 cell-surface antigen, CD 109 antigen, integrin β1, and carboxypeptidase D [39-42].