Groups of mice (n = 5) were injected s.c. with 2 × 105 D2F2/E2 cells on the right hind flank on day 0. On days 3 and 6 (indicated by black arrows), the challenged mice were vaccinated with 100 μg of 4TO7 PMVs protein transferred with GPI-HER-2, GPI-IL-12, and GPI-B7-1 s.c. on the left hind flank. Tumor area was measured by multiplying the length and width of the tumor. (Statistical analysis: Repeated measures Two-Way ANOVA – Sidak’s multiple comparisons test; * p < 0.05, ** p < 0.01, **** p < 0.0001).