Consistently, we found a significant increase in the accumulation of intratumoral CD8+ T cells in mice receiving both CD73−/− T cells and anti-4-1BB treatment compared with other three groups (Fig. 4d) while all mice had similar percentages of CD45+ tumor infiltrates (Fig. 4e), which was supported by our further observation that these CD8+ T cells from this group gained the highest levels of proliferating capacity (Ki67+) (Fig. 4f). Here, MKI67 is linked to neoplasm.