NFKB1 and infection: External stimuli, including infection factors, proteins, stress signals, and proinflammatory cytokines released by necrotic cells can activate NF-κB.762 The main activated form of NF-κB is a heterodimer of the p50 or p52 subunit associated with the p65 subunit.762 NF-κB proteins are present in the cytoplasm and are associated with inhibitory proteins of IκB.