ANALYSIS OF FES KINASE-ACTIVITY IN MYELOID CELL-GROWTH AND DIFFERENTIATION

Fes is a nonreceptor protein tyrosine kinase that has been implicated in a variety of cytokine signal transduction pathways, as well as diff erentiation of myeloid cells. To address the role of Fes in these proc esses, we overexpressed a kinase-defective Fes protein in the factor-d ependent cell-lines, TF-1 and 32D. Proliferative responses to GM-CSF a nd interleukin 3, and the induction of differentiation by G-CSF were n ot altered by expression of the kinase mutant Fes protein, indicating that Fes kinase activity is not critical for these biological events i n these cell lines.