(Enamel metalloproteinase; Enamelysin; Matrix metalloproteinase 20)p65 is a subunit of the nuclear factor kappa-B, a second messenger, which activates the transcription of a number of genes in multiple tissues. The inhibitory effect of I-kappa-B upon NF-kappa-B in the cytoplasm is exerted primarily through the interaction with p65. Two heterodimers might form a labile tetramer. Subcellular location is at Nucleus, Cytoplasm. Nuclear, but also found in the cytoplasm in an inactive form complexed to an inhibitor (I-kappa-B). Tissue Specificity: Spleen; lower level in brain.