He is credited with elucidating some of the basic cellular machinery that propels the process of apoptosis, such as the cell-surface receptor, Fas. Early work with his colleague at the Osaka Bioscience Institute (OBI), Shin Yonehara, who had shown that a mouse antibody to Fas was involved in the cytolytic pathway, revealed that the antibody worked as an agonist; that is, that it contributed actively to the death of the cell rather than merely blocking proliferation.