β1 or β2 integrin ligation on human NK cells enhances WASp association with Pyk2 and Fyn tyrosine kinases. Human NK cells were left untreated (−) or stimulated with GAM cross-linked anti-β1 (TS2/16), anti-β2 (TS1/18), or anti-CD56 (C218) mAb for the indicated time periods at 37°C. Cell lysates were then immunoprecipitated with anti-Fyn (A) or with anti-Pyk2 mAb (B). The resulting immunocomplexes were resolved by 7.5% sodium dodecyl sulfate–polyacrylamide gel electrophoresis, transferred to nitrocellulose, and sequentially immunoblotted with anti-pTyr mAb (top), anti-WASp antiserum (middle), anti-Fyn antiserum, or anti-Pyk2 mAb as loading controls (bottom). Sizes are indicated in kilodaltons. These results represent 1 of 3 independent experiments.