Molecular mechanisms involved in macrophage survival, proliferation, activation or apoptosis

Macrophages play a critical role during the immune response. Like other cells of the immune system, macrophages are produced in large amounts and most of them die through apoptosis. Macrophages survive in the presence of soluble factors, such as IFN-g, or extracellular matrix proteins like decorin. The mechanism toward survival requires the blocking of proliferation at the G₁/S boundary of the cell cycle that is mediated by the cyclin-dependent kinase (cdk) inhibitor, p27^kip and the induction of a cdk inhibitor, p21^waf1.