T-box transcription factor T (TBXT, T brachyury transcription factor, protein T) is a nuclear transcription factor that is involved in the regulation of genes necessary for mesoderm formation and differentiation; it is important for notochord and axial development and determination of the posterior mesoderm. In normal tissues, it is expressed in testis and not in most other tissues. It is expressed in chordomas and hemangiomas and in other tumor types is associated with poor outcome. Staining is used to distinguish chordoma and hemangioblastoma from clear cell renal cell carcinoma, chondrosarcoma, and choroid meningiomas. In normal tissues, it is expressed in the nuclei of cells within the pituitary and spermatogonia. References: Clin Cancer Res. 2007;13(8):2471-2478. doi: 10.1158/1078-0432.CCR-06-2353; Clin Cancer Res. 2012;18(14):3868-3879. doi: 10.1158/1078-0432.CCR-11-3211; Dis Markers. 2014;2014:514753. doi: 10.1155/2014/514753; Mod Pathol. 2011;24(3):425-429. doi: 10.1038/modpathol.2010.196; Ann Surg Oncol. 2013;20 Suppl 3:S509-S516. doi: 10.1245/s10434-013-2914-9; J Natl Cancer Inst. 2014;106(5): pii: dju054. doi: 10.1093/jnci/dju054; Gastric Cancer. 2016;19(2):651-659. doi: 10.1007/s10120-015-0505-0.