The p65 (RELA) heterodimer is the most abundant form of NFKB. This gene is located on 11q13, which consists of 10 exons and spans about 8.1 kb of DNA. In rat sciatic nerves, the expression of the activated p65 subunit of NFKB was high in the nuclei of premyelinating Schwann cells and then progressively declined until it was nearly absent in adults. The transcriptional activity of NF-kappa-B is stimulated upon phosphorylation of its p65 subunit on serine-276 by protein kinase A (PKA). The transcriptional coactivator CBP /p300 associates with NF-kappa-B p65 through 2 sites, an N-terminal domain that interacts with the C-terminal region of unphosphorylated p65, and a second domain that only interacts with p65 phosphorylated on serine-276.