GAB1 and lung adenocarcinoma: To further confirm that Shp2, Gab1-Shp2 interaction, and Shp2 PTP activity mediate Erk1/2 activation in lung adenocarcinoma cells that harbor mutant EGFR, we compared the pErk1/2 level in isogenic HCC827 cells containing two different Dox-inducible Shp2 shRNAs (Fig. 2C).