Fas belongs to the tumor necrosis factor/nerve growth factor receptor family. The Fas ligand binds to its receptor, Fas, and induces apoptosis in Fas-bearing cells. The granulocyte colony-stimulating factor receptor (G-CSFR) is a member of the hemopoietic growth factor receptor family. G-CSF induces its dimerization and regulates the proliferation and differentiation of neutrophilic granulocytes, We constructed hybrid receptors between Fas and G-CSFR and expressed them in the mouse T cell line WR19L or the mouse myeloid interleukin-3-dependent FDC-P1 cell line. The Fas ligand or an agonistic anti-Fas antibody stimulated proliferation of the FDC-P1 transformants expressing a chimera consisting of the Fas extracellular and G-CSFR cytoplasmic regions. On the other hand, G-CSF could not induce apoptosis in the transformants expressing the chimera consisting of the G-CSFR extracellular and Fas cytoplasmic regions, but these cells were killed by a polyclonal antibody against G-CSFR. These results indicated that receptors belonging to different receptor families can be functionally exchanged and confirm that a homodimer of G-CSFR can transduce the growth signal, whereas Fas must be oligomerized (probably trimerized) to transduce the apoptotic signal.