Synthetic mucin fragments: 3-O-[2-acetamido-4,6-di-O-acetyl-2-deoxy-3-O -(2,3,4,6-tetra-O-acetyl-b-D-galactopyranosyl)-b-D-glucopyranosyl] -2,4,6-tri-O-acetyl-a-D-galactopyranosyl bromide and p-nitrophenyl 3-O-(2-acetamido-2-deoxy-3-O-b-D-galactopyranosyl-b-D glucopyranosyl)-b-D-galactopyranoside.