The REL gene encodes c-Rel, a transcription factor that is a member of the Rel/NFKB family, which also includes RELA (MIM 164014), RELB (604758), NFKB1 (MIM 164011), and NFKB2 (MIM 164012). These proteins are related through a highly conserved N-terminal region termed the Rel domain, which is responsible for DNA binding, dimerization, nuclear localization, and binding to the NFKB inhibitor.
