A synthetic trisaccharide with the Neu5Acα2-3Galβ1-3GalNAc sequence, corresponding to the sialyl-T antigen (sialyl core 1) — a tumor-associated carbohydrate antigen and a sialylated mucin-type O-glycan. Sialyl-T antigen presentation on mucins is a hallmark of many epithelial cancers and is recognized by selectins and certain Siglecs. Used as a probe and reference standard for cancer glycobiology, anti-sialyl-T antibody research, and as a substrate for sialidases.