An important role of Gab2 in mediating the pathogenic effects of Ptpn11^D61G/+ mutation in stem cells. WT, Gab2^−/−, Ptpn11^D61G/+, and Ptpn11^D61G/+/Gab2^−/− mice were generated as described in Figure 6. The mice were analyzed for the percentage of LSK cells in the BM (A; n = 6 per group), cell-cycle status (B; n = 5-8), and apoptosis (C; n = 5 per group) as described in Figure 1. (D) LSK cells were sorted from these mice and cultured in IL-3 (0 or 2 ng/mL) and 10% FBS-containing Iscove Modified Dulbecco media (5 × 10³ cells/well). After 7 days of in vitro culture, total cell numbers were determined (n = 3 per group). (E) Percentages of myeloid (Mac-1⁺/Gr-1⁺) cells differentiated from the sorted LSK cells in the presence of IL-3 (2 ng/mL) were assessed by FACS analysis (n = 6 per group). P values for comparisons between Ptpn11^D61G/+/Gab2^−/− and Ptpn11^D61G/+ mice were determined by Student t tests. Statistical significance among 4 groups in all panels was verified by 2-way ANOVA followed by Bonferroni or 1-way ANOVA followed by the Tukey posttest.