Human c-FES is a nuclear tyrosine kinase

FES is a non-receptor protein tyrosine kinase expressed in hematopoietic progenitors and differentiated myeloid cells. It has recently been implicated in granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3) and erythropoietin signal transduction. To better understand the role played by FES in normal and neoplastic hematopoiesis, we used cell fractionation techniques to examine the subcellular localization of FES in myeloid cells and cell lines. FES was observed in the nuclear, granular and plasma membrane fractions of primary human neutrophils and the myeloid leukemia cell line, HL-60. The nuclear localization was confirmed by immunocytochemistry of neutrophils.