Tyrosine Phosphorylation of vav Protooncogene Product in Primary Human Myelogenous Leukemic Cells Stimulated by Granulocyte Colony-Stimulating Factor

Granulocyte colony-stimulating factor(G-CSF), but not granulocyte-macrophage CSF(GM-CSF), induced tyrosine phosphorylation of 95-kDa protein in 13 cases of primary human acute myelogenous leukemic cells. Electrophoretic mobility of 95-kDa phosphoprotein and the protooncogene product p95 vav was identical. In addition, p95 vav was tyrosine-phosphorylated only in G-CSF-stimulated cells. In contrast to primary leukemic cells, amount of p95 vav was under detectable level and G-CSF did not induce tyrosine phosphorylation of 90-100-kDa proteins in human neutrophils. These results indicate specific involvement of vav product in signaling pathway of G-CSF in primary human leukemic cells.