IFN-γ release of NK cells stimulated by indicated MICA mutants at a concentration of 11nM (D) and 22nM (E). Data information: bars in (E), and data point in (F) represent mean values. Error bars represent mean ± SEM for biological triplicate experiments. **P < 0.01, ***P < 0.001, **** P <0.0001 (two-tailed unpaired t-test). 