| Regulation of mouse PECAM 1 tyrosine phosphorylation by the Src and Csk families of protein tyrosine kinases . ^^^ Through reconstitution experiments in COS 1 cells , we determined that mouse PECAM 1 could be tyrosine phosphorylated by Src related PTKs and Csk related PTKs , but not by other kinases such as Syk , Itk , and Pyk 2 . ^^^ In other studies , we demonstrated that phosphorylation of PECAM 1 by Src or Csk family kinases was sufficient to trigger its association with SHP 2 . ^^^ Taken together , these findings indicated that the Src and Csk families of kinases are strong candidates for mediating tyrosine phosphorylation of PECAM 1 and triggering its association with SH 2 domain containing phosphatases under physiological circumstances . . ^^^ |