It was shown that the C-terminal domain of BCL-6 physically interacts with the Rel-homology domain of NF-κB in vitro as with AP1 family members and that BCL-6 behaves as a mutual negative regulator of NF-κB target genes in diffuse large B-cell lymphomas [68–69]. This evidence concerns the gene NFKB1 and diffuse large B-cell lymphoma.