A novel neo-glycolipid containing sialyl Lewis X determinant carried on the mucin GlcNAc beta 1-6GalNAc alpha core structure has been designed and synthesized. By employing this compound as a probe, the structure required for the recognition of anti-cancer antibodies, NCC-ST-439, has been elucidated. (c) 2005 Elsevier Ltd. All rights reserved.