Expression of wild-type PECAM-1 on the surface of wild-type and SHP-2-negative B-cell transfectants.

(A) Wild-type (left) or SHP-2–negative (right) DT40 cells were lysed in Triton X-100, and lysates were analyzed by anti-SHP-2 (αSHP-2; top) and anti-SHP-1 (αSHP-2; bottom) immunoblots. Note that wild-type DT40 cell lysates contain both SHP-2 and SHP-1, whereas SHP-2–negative DT40 cell lysates contained SHP-1 but not SHP-2. (B) Wild-type (left) and SHP-2–negative (right) DT40 cells were transfected with wild-type human PECAM-1. Transfectants were 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. Transfectants chosen for analysis expressed equivalent levels of cell surface PECAM-1.