RELA (v-rel reticuloendotheliosis viral oncogene homolog A), also known as Nuclear factor NF-kappa-B p65 subunit, or Transcription factor p65, is a transcription factor expressed in growth plate chondrocytes where it facilitates chondrogenesis. The v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) gene encodes the major component of the NF-?B complex. NF-kappaB is a generic name for an evolutionarily conserved transcription-factor system that contributes to the mounting of an effective immune response but is also involved in the regulation of cell proliferation, development, and apoptosis. The implication of NF-kappaB in central biological processes and its extraordinary connectivity to other signaling pathways raise a need for highly controlled regulation of NF-kappaB activity at several levels. The mammalian Rel/NF-kappaB family of transcription factors, including RelA, c-Rel, RelB, NF-kappaB1 (p50 and its precursor p105), and NF-kappaB2 (p52 and its precursor p100), plays a central role in the immune system by regulating several processes ranging from the development and survival of lymphocytes and lymphoid organs to the control of immune responses and malignant transformation.