Anti-MAP3K21 antibodies are used in the immunodetection of the protein mitogen-activated protein kinase kinase kinase 21. In humans, the canonical protein has a reported length of 1036 amino acid residues and a mass of 114 kDa. Up to 3 different isoforms have been reported for this protein. A member of the STE Ser/Thr protein kinase protein family, MAP3K21 is a reported regulator of TLR4 signaling. Post-translational modifications have been described, including phosphorylation. Synonyms for this target antigen include mitogen-activated protein kinase kinase kinase MLK4 and mixed lineage kinase 4. MAP3K21 gene orthologs have been reported in the mouse, rat, bovine, chimpanzee and chicken species. A number of MAP3K21 antibodies have been mentioned in research publications and have associated citations. Western Blot is a widely used application for these antibodies. ELISA and Immunohistochemistry are also common applications.