NF-kappaB (NFκB) proteins comprise a family of eukaryotic transcription factors that are involved in the control of a large number of cellular and organismal processes. In addition, these transcription factors are associated with many diseases including cancer and arthritis. NFκB commonly refers specifically to a p50-RelA(p65) heterodimer, which is the major Rel/NFκB complex in most cells. P65-p65 and p50-p50 heterodimers have been demonstrated to bind on DNA as well. NFκB is present as a latent, inactive, IκB-bound complex in the cytoplasm. When a cell receives any of a multitude of extracellular signals, NFκB rapidly enters the nucleus and activates gene expression. Signosis has developed the NFκB-p65 and NFκB p50 ELISA kits for sensitive and specific analysis of the activities of NFκB in a high throughput way. The kit can be used for human, mouse and rat samples.