Abscisic acid (ABA) is a plant hormone. ABA functions in many plant developmental processes, including bud dormancy, and can be involved in stress responses. It is degraded by the enzyme (+)-abscisic acid 8'-hydroxylase into phaseic acid.
p-Azobenzenearsonate is an arsenical. It causes antibody formation and delayed hypersensitivity when bound to aromatic amino acids, polypeptides or proteins. It is used as an immunologic research tool.