HLX1 homeobox protein (H2.0-like homeobox protein) is a transcription factor required for TBX21/T-bet-dependent maturation of Th1 cells as well as maintenance of Th1-specific gene expression. HLX1 is involved in embryogenesis and hematopoiesis and is located in the nucleus. HLX1 can be found at low levels in normal B and T-cells, and at high levels in activated lymphocytes and monocytes. HLX1 can also found in thymus, tonsil, bone marrow, developing vessels, and fetal brain tissue.