Figure 4. Gab2 deletion reverses the enhanced PI3K/Akt/mTOR signaling caused by the Ptpn11^E76K/+ mutation.

(A) BM-derived macrophages generated from pI-pC administered Ptpn11^E76K/+/Mx1-Cre⁺/Gab2^+/+ and Ptpn11^E76K/+/Mx1-Cre⁺/Gab2^−/− mice were starved in serum and cytokine-free medium for 48 hours and then stimulated with GM-CSF (50 ng/mL) for the indicated periods of time. Whole cell lysates were prepared. Levels of p-Erk, p-Akt, and p-Stat5 were determined by immunoblotting analyses. Blots were striped and reprobed with anti-Erk, anti-Akt, anti-Shp2, and anti-Gab2 antibodies to check for protein loading and Gab2 deletion efficiency. Three independent experiments with three pairs of mice were performed. Similar results were obtained in each. (B) MPN cell lysates prepared from Ptpn11^E76K/+/Mx1-Cre⁺/Gab2^+/+ and Ptpn11^E76K/+/Mx1-Cre⁺/Gab2^−/− mice 10 weeks after pI-pC administration when MPN was fully developed were immunoblotted with p-S6 and p-4E-BP1. Shp2 levels in the tissue lysates were examined by anti-Shp2 immunoblotting. Each lane represents an individual mouse.