In hydra, differentiated ectodermal cells of the foot region containaperoxidaseactivity that canbeusedas amarker for foot-specific differentiation processes. Because the expres-sion of the gene coding for the peroxidase must be tightly regulated during foot-specific differentiation, characteriza-tion of the protein and cloning of the corresponding gene shouldprovide valuable tools for gettingdeeper insights into the regulation of foot-specific differentiation.