FIG. 5.
SHIP required for maximal phosphorylation of Shc in response to BCR plus FcR co-cross-linking. (A and B) DT40 cells (A) or A20 cells (B) were left unstimulated or stimulated by BCR cross-linking alone or BCR plus FcR coligation. Cells were lysed, and Shc was immunoprecipitated (IP) with polyclonal anti-Shc antibody. Immunoprecipitates were analyzed by immunoblotting with antiphosphotyrosine antibody (dpTyr) (upper panels) or anti-Shc antibody (lower panels). The p52 and p46 isoforms of Shc are indicated by arrows. (C) Parental DT40 cells, SHIP−/− DT40 cells, or SHIP−/− DT40 cells reconstituted with SHIPwt, SHIP1–900, or SHIPY917/1020F were left unstimulated (lanes —) or stimulated by BCR plus FcR co-cross-linking (lanes +), and Shc phosphorylation was analyzed as described above. Sizes are shown in kilodaltons.