Pantoprazole (BY1023; 200 mg/kg; IP; once a week for 3 weeks) significantly increases tumor growth delay of MCF-7 xenografts combined with Doxorubicin. Pantoprazole (0.3-3 mg/kg, p.o.) dose-dependently decreases both basal acid secretion in pylorus-ligated rats and the stimulated acid secretion induced by mepirizole in acute fistula rats.