Mitogenic response to colony-stimulating factor 1

Abstract

The proliferative effects of colony-stimulating factor 1 (CSF-1) on cells of the mononuclear phagocyte lineage are mediated by the CSF-1 receptor tyrosine kinase, which triggers intracellular signal transduction through multiple second messenger pathways. CSF-1 is required throughout G1 to stimulate both immediate- and delayed-early responses that ensure entry of macrophages into S phase. Because CSF-1 induces the expression of different sets of cellular genes during early and late G1, products of the immediate-early response might modulate the effects of ensuing receptor signals to facilitate G1 progression. Targets of the delayed-early response include novel cyclin genes that may play a role in S phase commitment.