Protection of mice immunized with hTRP-2 from syngeneic tumor challenge. Groups of 3-5 C57BL/6 mice (wild type) and mice of the same background deficient in IL4 (IL4^-/-) or IFN-gamma (IFN-gamma^-/-) were immunized weekly with hTRP-2. Intravenous tumor challenge was performed 7 days after the last immunization and lung metastases were counted 14 days after challenge. Error bars represent standard error of the mean.