Anti-T-box 21 antibodies are protein reagents that detect specific antigens. The T-box 21 antigen is another term for the human protein T-box transcription factor 21, encoded by the TBX21 gene. The protein is known to function in the regulation of transcription and the regulation of cell differentiation, among other biological roles. Canonically, it has an amino acid length of 535 residues and a mass of 58.3 kilodaltons. Its subcellular localization is in the nucleus and it is reported to have t-cell specific expression. Other alias names for T-box 21 include IMD88, T-PET, and T-bet. Over 440 citations in the literature describe the use of T-box 21 antibodies in research. These antibodies are most commonly used in Western Blot experiments, among other applications.