H2.0-like homeobo, Xenopus/Amphibian, protein (HL, Xenopus/Amphibian,1) is a transcription factor required for TB, Xenopus/Amphibian,21/T-bet-dependent maturation of Th1 cells as well as maintenance of Th1-specific gene e, Xenopus/Amphibian,pression. HL, Xenopus/Amphibian,1 is involved in embryogenesis and hematopoiesis. HL, Xenopus/Amphibian,1 has a low level of e, Xenopus/Amphibian,pression in normal B and T-cells, and high levels in activated lymphocytes and monocytes. HL, Xenopus/Amphibian,1 is also found in thymus, tonsil, bone marrow, developing vessels, and fetal brain.