Tyrosine 719 in KIT receptor is sufficient for recruiting protein complex involving p85α, SHP2, and Gab2 to KITD814V. (A) The 32D cells bearing WT KIT or KITD814V were starved for 8 hours in serum- and growth factor-free medium followed by incubation with or without II-B08 (20μM) for 1 hour. After incubation, equal amounts of protein lysates were subjected to immunoprecipitation with anti-SHP2 or anti-p85α antibodies followed by Western blot analysis using anti-p85α, anti-SHP2, or anti-Gab2 antibodies. Similar results were observed in 2 independent experiments. (B) Primary BM-derived cells expressing WT KIT or KITD814V from WT or Gab2^−/− mice were starved and subjected to proliferation assay in the absence of growth factors by thymidine incorporation. Bars represent the mean (± SD) thymidine incorporation from 1 of 3 independent ex-eriments performed in quadruplicate. *P < .01, WT-KITD814V vs Gab2^−/−-KITD814V. (C) The 32D cells bearing WT KIT, KITD814V, KITD814V-Y719, or KITD814V-F7 were starved of serum and growth factors for 8 hours, and equal amounts of protein lysates were subjected to immunoprecipitation with an anti-KIT antibody, anti-p85α antibody, or anti-SHP2 antibody followed by Western blot analysis using anti-KIT, anti-p85α, anti-SHP2, or anti-Gab2 antibodies as indicated. Similar results were observed in 2 or 3 independent experiments.