Normal antibody-dependent cell-mediated cytotoxicity in Zap70-deficient and Syk-deficient NK cells. (A-B) ADCC induced by coating a chromium-labeled RMA cell line with anti-CD90 in the absence (♦) or presence (◇) of CD16-blocking antibody 2.4G2; cells alone served as an additional control (○). (A) Comparison between WT and Zap70^−/− NK cells. (B) Comparison between WT and Sykb^−/− NK cells from chimeric mice. Data are representative of 2-3 independent experiments.