CMP-N-acetylneuraminate-beta-1,4-galactoside alpha-2,3-sialyltransferase (ST3GAL3), located on the Golgi membrane, mediates the transfer of sialic acid (Neu5Ac, N-acetylneuraminic acid) in an α2,3 linkage to the terminal galactose of Gal-beta-1,3-GlcNAc- and Gal-beta-1,4-GalNAc- sequences found on glycoproteins and glycolipids (Kitagawa & Paulson 1993). The product, Type 1 monosialylgalactosylgloboside (Type 1 MSGG) is the precursor to sialyl Lewis a (sLeA) (also known as the CA19-9 antigen), a tumour marker that is used primarily in the management of pancreatic cancer. Increased sialylation has been observed to be associated with malignant transformation and metastasis.