Vav1 and Vav3 are overexpressed and overactivated in p190-BCR-ABL ALL. (A) Representative immunoblot of phospho-Vav1 and phospho-Vav3 in human cells. Lanes 1 through 3 are CD34⁺ cells from healthy donors; lanes 4 through 6 are LDBM cells from healthy donors; lanes 7-9 are LDBM cells from patients with TEL-AML1⁺ B-ALL; and lanes 10 through 16 are LDBM cells from 7 patients with p190-BCR-ABL⁺ B-ALL. β-actin expression analysis was used as a loading control. Two independent experiments were run with the same specimens. (B) Normalized phosphorylation of Vav1 (empty bar) and Vav3 (solid bar) from the samples in panel A. The ratio was generated by dividing the densitometric value of each phosphorylated protein by that of β-actin from the same sample. Values represent average ± SEM. *P < .05; **P < .01. (C) Immunoblot of phosphorylated forms (Vav1-pTyr174 and Vav3-pTyr173) compared with total Vav1 and Vav3 in sorted murine B-220⁺/c-kit⁺/CD43⁺/EGFP⁺ B-cell progenitors transduced with either an empty vector (MIEG3) or p190-BCR-ABL.