Both DAP10 and DAP12 were required for complete NK cell inactivation. NK cells from mice lacking DAP12 function (DAP12ki) were exposed to RMA-H60 (■) or control RMA (□) cells. Effector cells were tested against RMA-H60, RMA/S, and anti-Thy1 mAb (αThy1)–coated RMA cells. As compared with wild-type controls, inactivation of ADCC and missing-self recognition in NK cells lacking DAP12 function (DAP12ki) is incomplete. The data shown are triplicate determinations from a single experiment. Error bars are SD.