The 12.14 monoclonal antibody specifically recognizes Nur77, a zinc-finger transcription factor also known as Nerve growth factor IB (NGFI-B), Testicular receptor 3 (TR3), or Nuclear protein N10. Nur77 is encoded by Nr4a1 (Nuclear receptor subfamily 4 group A member 1), an immediate-early response gene that belongs to the nuclear receptor superfamily. This inducible orphan nuclear receptor is comprised of an N-terminal transactivation domain, followed by a central DNA-binding domain and a putative C-terminal ligand-binding domain for which no ligand has been identified. In electrophoretic analyses, Nur77 migrates as diffuse protein bands between 67 and 88 kDa depending on its level of phosphorylation or other post-translational modifications. Nr4a1 expression can be rapidly induced by diverse stimuli in cells from primary and secondary lymphoid tissues and other tissues including the brain, muscle, ovary, and testis. Nur77 expression is rapidly upregulated by antigen-stimulated mouse thymocytes and may promote activation- induced apoptosis during negative selection. Ag receptor-mediated signaling by B cells, T cells, or T cell hybridomas can also lead to rapid upregulated Nur77 expression which may regulate cellular proliferation and survival. In response to certain growth factors, cytokines, inflammatory mediators, or stress-inducing stimuli, other cell types, including myeloid or stromal cell types, can upregulate Nur77 expression which affects their growth, differentiation, proliferation or survival. Clone 12.14 recognizes mouse Nur77 and reportedly crossreacts with human Nur77.