The Lnk SH2 domain is required for Lnk phosphorylation in BMMCs. (A) Schematic representation of WT and Lnk mutant forms cloned into the MIG retroviral vector. Point mutations in the different domains and in the carboxy-terminus tyrosine are indicated with an asterisk (*) or an F. (B) Lnk^−/− BMMCs transduced with control vector or Lnk forms were stimulated with SCF for 5 minutes. Cell lysates were immunoprecipitated with anti-Lnk antibodies. Western blot analysis with anti-pKit antibodies allowed identification of associated protein (top panel). Lnk protein expression is shown (bottom panel). White lines indicate repositioned gel lanes. (C) BMMCs expressing Lnk mutant forms were stimulated with SCF for the indicated times. Lnk phosphorylation was analyzed by immunoprecipitation with anti-pTyr, followed by immunoblotting with anti-Lnk antibodies.