PIK3R2 and cancer: We chose Grb2 and Shc family members (Grb2, Grb2(SH23), Grap, Grap2, ShcA, ShcA(ptb)) because of the known importance of Ras activation to tumorigenesis, and our earlier results linking Ras activation to erlotinib sensitivity (Fig. 4); and PI3Ks (p85A, P85B, P55G), because of the strong association between PI3K/Akt activity and cancer [40].