CEACAM6 and cancer: Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a glycosylphosphatidylinositol (GPI)-linked immunoglobulin superfamily member that is overexpressed in a variety of human cancers, especially gastrointestinal cancers [4], and functions as an intercellular adhesion molecule [4]–[6].