Anti-XO antibodies enable researchers to detect and measure the XO antigen in biological samples. This target is a reported synonym of the XDH gene, which encodes xanthine dehydrogenase. This protein is known to function in the apoptotic pathway, among other biological roles. The human version of XO has a canonical amino acid length of 1333 residues and a protein mass of 146.4 kilodaltons. It is reported to be localized in the cytoplasm and is secreted of cells and notably expressed in the lactating breast. Other names for this target antigen include XAN1 and XOR. ELISA and Western Blot are common applications for XO antibodies.