Blood group related antigens represent a group of carbohydrate determinants carried on both glycolipids and glycoproteins. They are usually mucin-type, and are detected on erythrocytes, certain epithelial cells, and in secretions of certain individuals. Sixteen genetically and biosynthetically distinct but inter-related specificities belong to this group of antigens, including A, B, H, Lewis a, Lewis b, Lewis x, Lewis y, and precursor type 1 chain antigens. This antibody belongs to the BG-7 group and detects the Lewis x (type 2 chain) blood-group antigen, which is expressed in gastrointestinal tumors, and lung cancers. It is found in crypt cells, which represent the proliferative compartment of the colonic mucosa, and strong homogeneous immunostaining is observed in most metastases and invasive cancer cells.