Characterization of Src family PTK and PECAM-1 expression by wild-type Jurkat T cells and the p56^lck-deficient Jurkat T-cell line, JCaM1.6.

(A) Wild-type Jurkat (left) or p56^lck-deficient JCaM1.6 (right) T cells were lysed in Triton X-100, and lysates were analyzed by anti-pp60^src (αSrc; top), anti-p59^fyn(αfyn; middle), and anti-p56^lck (αlck; bottom) immunoblots. Note that wild-type Jurkat T-cell lysates contain pp60^src, p59^fyn, and p56^lck, whereas JCaM1.6 T cells contain pp60^src and p59^fyn but not p56^lck. (B) Wild-type Jurkat (left) or p56^lck-deficient JCaM1.6 (right) T cells stained with normal mouse IgG1 (NMIgG) or with PECAM-1.3, a murine mAb specific for human PECAM-1 (αPECAM-1). Antibody-pretreated cells were then stained with FITC-conjugated GAM IgG and analyzed by flow cytometry. Both cell lines expressed equivalent levels of cell surface PECAM-1.