Decreased in vivo tyrosine kinase activity of p190

BCR/ABL SH2 mutants. Proteins from malignant pleural effusion-derived lymphoblasts from 2 different primary recipients of marrow transduced with p190 BCR/ABL wild-type (WT), R552K, or ΔSH2 were blotted with monoclonal antibodies against phosphotyrosine (upper panel) or Abl (bottom panel). Equal amounts of protein were loaded in each lane by Ponceau-S staining of the membrane, and equivalent amounts of p46 and p52 Shc proteins were detected in each lane after immunoblotting with anti-Shc antibodies (data not shown). Molecular size markers (kd) are at left. Arrowheads indicate the position of p110-120 and p62 proteins whose tyrosine phosphorylation is greatly decreased in the SH2 mutant-transduced cells. The position of Bcr/Abl is indicated by the asterisk. The decreased size of the p190 ΔSH2 protein (about 1 kd) is not apparent under these conditions.