Anti-PGA4 antibodies are used in the immunodetection of the protein pepsinogen A4. In humans, the canonical protein has a reported length of 388 amino acid residues and a mass of 42 kDa. It has been described to be a secreted protein. It is notably expressed in the stomach. A member of the Peptidase A1 protein family, PGA4 is known to be involved with proteolysis. Synonyms for this target antigen include pepsinogen 4, group I (pepsinogen A), pepsinogen-4, pregnancy-associated glycoprotein, and pepsin A-4. Some PGA4 antibodies may have been used in research and have associated citations. ELISA is a widely used application for these antibodies. Western Blot, Immunocytochemistry, Immunofluorescence, and Immunohistochemistry are also common applications.