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-kB 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-kB may also lead to inflammatory disorders, such as asthma and ulcerative colitis, and autoimmune disorders, such as rheumatoid arthritis. Also called NF-kappa B and nuclear factor-kappa B.