Discovered in 1986 as a DNA binding activity that recognized the immunoglobulin light chain intronic enhancer, NF-kappaB has been studied intensively for its role in controlling expression of genes involved in immune and inflammatory function. However, more recently, NF-kappaB has been implicated in controlling cell growth and oncogenesis. The link between NF-kappaB and cancer stems, in part, from the fact that this transcription factor is capable of inducing gene products that control proliferative responses and that suppress apoptotic cascades, such as those induced by tumor necrosis factor (TNF), expression of oncoproteins, and genotoxic stress. This latter observation is likely to be important in developing new approaches aimed at improving the efficacy of cancer chemotherapy.