Transcription factor required for TBX21/T-bet-dependent maturation of Th1 cells as well as maintenance of Th1-specific gene expression. Involved in embryogenesis and hematopoiesis (By similarity). Low level in normal B and T-cells, high level in activated lymphocytes and monocytes. Also found in thymus, tonsil, bone marrow, developing vessels, and fetal brain. Belongs to the H2.0 homeobox family. Truncated N-terminus.