The molecular control of proliferation and differentiation in hemopoietic cells.

The control of granulocyte and macrophage formation and function offers many insights into the developmental processes involved in hemopoiesis. Regulation of granulocyte and macrophage populations is mainly controlled by the actions of four glycoprotein regulators--the colony stimulating factors. These factors exhibit some redundancy in their actions but each is capable of regulating multiple events in the production, differentiation commitment, maturation and functional activities of the cells. The design of this regulatory system is such that it can ensure precise cell production under basal conditions but is also able to achieve large variations in cell production in response to emergency situations.