B cell Lymphoma 3 is a member of the IkB subfamily of inhibitors. This subfamily is part of the NF-kB transcription factor protein family and it is suggested that a balance in the concentration of various NF-kB family members regulates apoptosis and survival of activated T cells. Bcl-3 has been shown to have versatile functions such as cytoplasmic activation of p50 homodimers, translocation to the nucleus, and modulation of the transcriptional machinery in the nucleus. Bcl-3 activity often relies on several nuclear interacting proteins such as Tip60, Jab1, Bard1, and Pirin. The Mouse Bcl-3 coding region exhibits 80 % homology with Human Bcl-3 which is associated with human B-cell chronic lymphocytic leukemias (CLLs). Bcl-3 is detected in various tissues such as spleen and other lymphoid organs.Synonyms: B-cell lymphoma 3-encoded protein, BCL3, BCL4, D19S37