CTLA4 and neoplasm: The importance of the immune system for tumor control seen in the Rnf5−/− mice was confirmed upon administration of antibodies depleting CD4+ (Fig. 1g) or CD8+ (Fig. 1h) T cells, which abrogated the ability of Rnf5−/− mice to inhibit melanoma tumor growth, with a small additive effect upon CTLA4, but not PD-1 blockade (Supplementary Figure 1J, K).