Anti-CDK9 antibodies are used in the immunodetection of the protein cyclin dependent kinase 9. In humans, the canonical protein has a reported length of 372 amino acid residues and a mass of 42.8 kDa. Its subcellular localization is in the nucleus and cytoplasm. Up to 2 different isoforms have been reported for this protein. It is ubiquitously expressed across many tissue types. A member of the CMGC Ser/Thr protein kinase protein family, CDK9 is known to be a protein kinase involved in the regulation of transcription. Post-translational modifications have been described, including ubiquitination, acetylation and phosphorylation. Synonyms for this target antigen include CDC2L4, CTK1, PITALRE, TAK, CDC2-related kinase, and C-2k. CDK9 gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species. Over 230 citations in the literature describe the use of CDK9 antibodies in research. Western Blot is a widely used application for these antibodies. ELISA, Immunofluorescence, and Immunohistochemistry are also common applications.