CD70 reverse signaling in NK cells improves tumor control. (A-F) MC57 and MC57-CD27-trunc tumor fragments were transplanted SC into the flanks of RAG^−/− (A,C,F), RAGγc^−/− (B), and BL/6 (D) mice. Mice were treated with anti–Asialo-GM1 or control-IgG (C-D) or with FR70 or control IgG (F) at days −1, 0, and every second day after tumor transplantation. Tumor size was measured at the time points indicated. Data are shown as mean ± SEM of 5 to 10 mice in each group; representative of 3 independent experiments. (E) CD70 expression on tumor infiltrating NK cells from 3 tumor-bearing mice in each group at day 20 after transplantation. Histogram shows MFI of CD70 measured by FACS, representative of 3 independent experiments. Statistics: 2-way ANOVA (A-D,F), Student t test (E).