 The G-CSF receptors belongs to a family of cytokine receptors known as the "hematopoietin receptor family".The granulocyte colony-stimulating factor receptor is present on precursor cells in the bone marrow, and, in response to stimulation by G-CSF, initiates cell proliferation and differentiation into mature neutrophilic granulocytes and macrophages.The G-CSF-R is a transmembrane receptor that consists of an extracellular ligand-binding portion, a transmembrane domain, and the cytoplasmic portion that is responsible for signal transduction.