Shc and p140 are constitutively phosphorylated on tyrosine in AML cells. (A) Cell lysates from unstimulated (−) or hGM-CSF–stimulated (+) TF-1 cells and lysates of primary leukemia cells obtained from two patients with AML (AML-1 and AML-2), CLL, and a lysate of PBMCs obtained from a healthy donor were immunoprecipitated with anti-Shc antibodies and subjected to antiphosphotyrosine immunoblotting (P.Tyr). (B) Anti-Shc immunoprecipitates of lysates from hGM-CSF–stimulated TF-1 cells (lane 1) and primary AML (AML-3 through AML-8; lanes 2 through 7) were analyzed by antiphosphotyrosine immunoblotting. The positions of p52^Shc, p66^Shc, p61, p140, and p200 are indicated on the left. Molecular weight marker bands are indicated on the right.