C-myc and c-ets (1 and 2) genes are cellular homologues of the oncogenes carried by the avian myelocytomatosis virus, MC29, and the avian acute leukemia virus, E26, respectively. These genes are thought to have some role in the pathogenesis of these viruses, and antibodies to the products of these genes are planned for the biological and biochemical characterization of these proteins. So far, a monoclonal antibody against the myc gene products and three monoclonal antibodies against the ets-2 protein have been generated and described in previous reports. This year, the monoclonal antibodies against the ets-2 protein have been used to characterize the c-ets protein. By subcellular fractionation and immunocyto- chemical technique, the human ets-2 protein was demonstrated in the nucleus, and a minor amount of the protein was also found in the cytoplasm. Pulse-chase experiments and in vivo labeling with (32P) showed that the ets-2 protein is a short-lived phosphoprotein. Tumor promoter, 12-0-tetradecanoyl-phorbol-13-acetate (TPA), and synthetic diacylglycerol, 1-oleoyl-2-acetyl glycerol both of which activate protein kinase C, stabilized the ets-2 protein, thereby quickly elevating its steady-state level. These results point to the possibility that the ets-2 protein has a role in the protein kinase C pathway of signal transduction as a nuclear effector.