CD4 and neoplasm: In four independent B16ova in vivo experiments without antibody treatment, PD-L1, PD-1 and CTLA-4 were expressed on tumor-infiltrating CD4+ and CD8+ cells, and no significant differences between wild-type and Cblb knockout mice were detected: wt CD8+ PD-1+: 56.0% ± 5.7%; Cblb−/− CD8+ PD-1+: 50.3% ± 4.5%; wt CD8+ CTLA-4+: 17.1% ± 4.5%; Cblb−/− CD8+ CTLA-4+: 18.0% ± 4.2% (n = 10) (Figure 5E, 5F and data not shown).