C WT and SKAP55−/− mice were s.c. injected with MO5 melanoma cells followed by s.c. two injection of OVA257-264-pulsed DCs at day 7 and day 14. anti-PD-1 monoantibody or IgG controls were i.v. injected three times at day 7, day 10, and day 14 (50 μg/injection). The diameter and volume of tumors were measured every three days (mean ± SEM, n ≥ 5 mice). 