FUT4 and neoplasm: However, it remains open to what extent other known carbohydrate tumor markers such as, for instance, CD175 (Tn), CD175s (sialyl-Tn), CD174 (Lewis Y), CD15 (Lewis X), CD15s (sialyl-Lewis X), CA19-9 (sialyl-Lewis a), or some subtypes of A or H (blood group-related glycans) might also be carried on CSC marker proteins.