Zeta’s mouse monoclonal antibody recognizes HepPar-1. Zeta’s HepPar-1 clone OCH1E5 is useful in studying hepatocellular tumors. Zeta’s antibody to HepPar-1 may be useful in differentiating clear cell hepatocellular carcinomas from other clear cell malignancies. Expression of HepPar-1 has been shown in the literature to be useful in differentiating hepatoblastoma of embryonal type from small round cell tumors of childhood. The HepPar-1 antibody (clone OCH1e5) labels an antigen in the mitochondrial fraction of the liver homogenates.