C-Rel is a member of the Rel/NF-κB transcription factor family that forms homo or heterodimers with family members such as RelA/p65, RelB, NF- κB1/p105, and NF-κB2/p100. The NF-κB complex is retained in cytoplasm by the inhibitor IκB protein in unstimulated cells. Upon activation, IκB is degraded via the ubiquitin-proteasome pathway, which results in nuclear translocation of the active NF-κB complex. While other NF-κB transcription factors are expressed in most cell types, relatively higher levels of c-REL expression are found in hematopoietic cells. c-REL is thought to play key roles in regulating proliferation, differentiation, and survival of B and T lymphocytes.