In HTLV-1 infection, Tax-mediated NF-κB activation is recognized as a crucial factor associated with the development of HTLV-1-associated diseases [41], since NF-κB, which consists of five molecules (RelA (p65), RelB, c-Rel, p50, and p52) that form transcriptionally active complexes in various combinations, has an essential role in inflammation, innate immunity, and many steps of cancer initiation and progression [42]. This evidence concerns the gene RELA and cancer.