Anti-SPACA9 antibodies are used in the immunodetection of the protein sperm acrosome associated 9. In humans, the canonical protein has a reported length of 222 amino acid residues and a mass of 25.2 kDa. Its subcellular localization is in the nucleus, cytoplasmic vesicles, and cytoplasm. Up to 2 different isoforms have been reported for this protein. It is notably expressed in the testis, nasopharynx, fallopian tube, endometrium, and bronchus. SPACA9 is a known microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) of multiciliated respiratory cells and the distal singlet microtubules of monoflagellated spermatozoa. Synonyms for this target antigen include Mast, sperm acrosome-associated protein 9, Rsb66 homolog, and C9orf9. SPACA9 gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species. Western Blot is a widely used application for the SPACA9 antibodies listed below. In addition, ELISA is also a common application.