Anti-HEXIM P-TEFb complex subunit 1 antibodies are used for the immunodetection of the protein encoded by the HEXIM1 gene. In humans, the canonical protein has a reported length of 359 amino acid residues and a mass of 40.6 kDa. Its subcellular localization is in the nucleus and cytoplasm. It is widely expressed across many tissue types. A member of the HEXIM protein family, it is a reported transcriptional regulator which functions as a general RNA polymerase II transcription inhibitor. Other names for this target antigen include EDG1, HIS1, MAQ1, protein HEXIM1, HMBA-inducible, and CLP1. Gene orthologs have been identified in the mouse, rat, bovine, frog, chimpanzee and chicken species.