Pyk2 is tyrosine phosphorylated and associates with Zap-70 and Vav in Jurkat cells in response to SDF-1α/CXCL12. Cells were treated without and with SDF-1/CXCL12. (A) Pyk2 was immunoprecipitated from cell lysates of nonstimulated or SDF-1α/CXCL12–stimulated cells and was analyzed by Western blotting with antiphosphotyrosine (bottom panel) and Pyk2 (middle panel). As a control, control IgG–immunoprecipitated lysates were immunoblotted with anti-PyK2 Ab (bottom panel). (B) Anti-PyK2 (top two panels) or control IgG (bottom two panels) immunoprecipitates were immunoblotted with anti–Zap-70 or Vav Ab. (A-B) Results are representative of at least 3 experiments.