Anti-CEA cell adhesion molecule 21 antibodies are used for the immunodetection of the protein encoded by the CEACAM21 gene. In humans, the canonical protein has a reported length of 293 amino acid residues and a mass of 32.4 kDa. Its subcellular localization is in the membrane. Alternative splicing is reported to yield 3 different isoforms for this protein. It is a member of the CEA protein family. Post-translational modifications have been described, including glycosylation. Other names for this target antigen include carcinoembryonic antigen related cell adhesion molecule 21, and carcinoembryonic antigen-related cell adhesion molecule 21.