SLP-76 is phosphorylated and recruited to plasma membrane clusters following Ly49D receptor stimulation. (A) Ly49D⁺ splenic NK cells were enriched and expanded in IL-2 for 6 days. The expanded NK cells were then left unstimulated or stimulated with soluble isotype Ct Ab or anti-Ly49D Ab for 1 or 10 minutes and analyzed for total and phosphorylated SLP-76 by western blot. One representative of 3 independent experiments is shown. (B) Splenic NK cells from GFP-tagged SLP-76–transduced BM chimeric mice were enriched for Ly49D expression, expanded in IL-2 for 6 days, and stimulated on an isotype control Ab or anti-Ly49D Ab-coated surface. Clustering of SLP-76 at the plasma membrane was imaged by TIRF microscopy. Scale bar, 45 μm. One representative of 16 independent experiments is shown.