CD79a antibody is an intracellular component of the signal transduction pathway of the B-cell Receptor, appearing at pre-B-cell stage and persisting until the plasma cell stage. Studies have shown that CD79a is found in a majority of acute leukemia of precursor-B-cell-type as well as B-cell neoplasms, B-cell lymphomas and some myelomas. It is not present in myeloid or T-cell lines. This antibody labels precursor B-cell acute lymphoblastic leukemia, and has been suggested as the most reliable B-cell marker for this disorder. CD79a is conserved across species, which may make it useful in the identification of B-cell lymphomas in species other than human.