Specificity for SHP-1 effect on ITAM signaling.

(A) Effect of SHP-1 vs SHP-2 on FcγRIIA-induced phagocytosis using a COS7 cell heterologous system.34 Bars represent SD. COS7 cells were transiently transfected with FcγRIIA and EGFP-tagged SYK kinase in the presence of SHP-1 or SHP-2. Phagocytic index was determined as defined in “Materials and methods.” (B) Flow cytometry is used to document that cotransfection conditions result in equal amounts of EGFP-tagged SYK kinase and FcγRIIA expression in all transfectant populations. (C) Western blot analysis of SHP-1 or SHP-2 expression in COS7 cells evaluated in panels A and B. We performed immunoblot analysis of all COS7 cell transfectants used in the above analysis of phagocytosis.