Review article

The pivotal role of tumor-associated mac-rophages (TAMs) in tumor progression is now well established. TAMs have been shown to influence multiple steps in tu-mor development including the growth, survival, invasion, and metastasis of tu-mor cells as well as angiogenesis and lymphangiogenesis in tumors. The mo-lecular circuits that polarize TAMs toward such a protumoral phenotype are now the focus of intense investigation. The tran-scription factor, nuclear factor–B (NF-B), is a master regulator of many cellular processes and been shown to regulate various pathways that impact on the func-tion of TAMs. Much evidence for this has come from the use of elegant transgenic murine tumor models in which modifica-tion of single components of the NF-B signaling pathway has been shown to regulate the pro-tumor repertoire of TAMs. Here, we outline this evidence and at-tempt to reconcile the various views that have emerged recently over the exact role of NF-B in this phenomenon. (Blood. 2009;113:3139-3146