ST6GAL1 and metastatic neoplasm: Corresponding to the results that the two Neu5Ac-α-2,6- residues were necessary for these CSC HPs binding (Figure 5E), the enzymes possibly catalyzing the sialylation reactions, ST6Gal1 [72] and ST6GalNAc5 [73], were found to be highly expressed in malignant and metastatic tumors and corresponding to a worse prognosis [74–76].