Anti-CAB39 antibodies are used in the immunodetection of the protein calcium binding protein 39. In humans, the canonical protein has a reported length of 341 amino acid residues and a mass of 39.9 kDa. Its subcellular localization is in the cytoplasm. A member of a the Mo25 protein family, CAB39 is a known component of the complex that binds and activates STK11/LKB1. Synonyms for this target antigen include MO25, MO25alpha, and CGI-66.