Cross-linking NK cell–activating receptors induces PKC-θ activation. (A) Equal amounts of protein from purified murine and human NK-cell lysates were loaded and then immunoblotted with anti–PKC-θ antibody. Lysates from Jurkat and CD8⁺ T cells were used as positive controls. (B) PKC-θ^−/− and WT NK cells were expanded in IL-2 and then stimulated with plate-bound anti-NK1.1 (left panel) or conjugated with fixed YAC-1 cells (right panel). Cells were lysed and analyzed by immunoblotting with anti–phospho-PKC-θ and anti–total ERK1/2 antibodies. One experiment of 3 is represented.