DIVERSITY AND SIMILARITY IN SIGNALING PATHWAYS OF HEMATOPOIETIC GROWTH-FACTORS IN HUMAN LEUKEMIA-CELL LINES

Diversity and similarity in signaling pathways of granulocyte colony-s timulating factor (G-CSF), granulocyte-macrophage colony-stimulating f actor (GM-CSF), interleukin-3 (IL-3), and stem cell factor (SCF) in fi ve human factor-responsive leukemia cell lines were investigated by im munoblotting to detect tyrosine phosphorylation of intracellular prote ins. G-CSF induced tyrosine phosphorylation of a set of proteins with few different components according to the cell lines. IL-3 also induce d phosphorylation of several proteins. In a lymphoid cell line, phosph orylation patterns induced by IL-3 were somewhat different from that i n myeloid cell lines. Phosphorylation patterns by G-CSF and those by I L-3 were similar in myeloid cell lines. In a cell line which responded to both IL-3 and SCF, almost similar sets of proteins were phosphoryl ated by each, although phosphorylation of a 92-KDa protein was specifi c to IL-3 and that of a 140-200-KDa protein was specific to SCF. Taken together, proliferative growth factors induced tyrosine phosphorylati on of similar sets of proteins with little difference according to eac h growth factor and each target cell line.