NF-κB is a protein complex that controls transcription of DNA. NF-κB is found in almost all animal cell types and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, ultraviolet irradiation, oxidized LDL, and bacterial or viral antigens. The NF-κB network consists of five family member protein monomers (p65/RelA, RelB, cRel, p50, and p52) that form homodimers or heterodimers that bind DNA differentially and are regulated by two pathways: the canonical, NF-κB essential modulator (NEMO)-dependent pathway and the noncanonical, NEMO-independent pathway. Activation of the NF-κB pathway is involved in the pathogenesis of chronic inflammatory diseases, such as asthma, rheumatoid arthritis, and inflammatory bowel disease. In addition, altered NF-κB regulation may be involved in other diseases such as atherosclerosis and Alzheimer’s disease and a variety of human cancers.