Fig. 3. The 15 PECAM-1 isoform becomes tyrosine phosphorylated on its ITIMs and binds to the phosphatase SHP-2. REN mesothelioma cells expressing equivalent amounts of WT, ITIM-less or 15 PECAM-1 were stimulated with pervanadate and PECAM-1 was immunoprecipitated. Upon stimulation, WT PECAM-1 became tyrosine phosphorylated, as indicated by the phosphotyrosine immunoblot, and bound to SHP-2. By contrast, the Y663,686F ITIM-less form of PECAM-1 neither becomes tyrosine phosphorylated nor binds to SHP-2. Similar to WT PECAM-1, the 15 PECAM-1 isoform was able to become tyrosine phosphorylated and bind to SHP-2.