Before revision: The sialyl Tn antigen (STn antigen) is formed by elongation with sialic acid (Neu5Ac(a2-6)GalNAc) .
After revision: rather than galactoseThe sialyl Tn antigen (STn antigen) is formed by elongation with sialic acid (Neu5Ac(a2-6)GalNAc) .