Four distinct colony-stimulating factors (CSFs) that promote survival, proliferation and differentiation of bone marrow precursor cells have been well characterized: granulocyte macrophage CSF (GMCSF), granulocyte CSF (GCSF), macrophage CSF (MCSF) and Interleukin-3 (IL-3, Multi CSF). Both GMCSF and IL-3 are multipotential growth factors, stimulating proliferation of progenitor cells from more than one hematopoietic lineage. In contrast, GCSF and MCSF are lineage restricted hematopoietic growth factors, stimulating final mitotic divisions and the terminal cellular maturation of the partially differentiated hematopoietic progenitors.