A group of proteins that help control many functions in a cell, including cell growth and survival. These proteins also control the body’s immune and inflammatory responses. NF-kappa B may be overactive or found in higher than normal amounts in some types of cancer cells. This may lead to cancer cell growth. High levels or overactivity of NF-kappa B may also lead to inflammatory disorders, such as asthma and ulcerative colitis, and autoimmune disorders, such as rheumatoid arthritis. Also called NF-kB and nuclear factor-kappa B.