Ready-to-use ELISA kits are available for the detection of sox21a, an alias of the protein, SRY-box transcription factor 21. The official gene symbol is SOX21. The protein, with a mass of 28.6 kDa and length of 276 residues, is reported to be nuclear. It may be known by other names, including: SRY-box 21, SRY (sex determining region Y)-box 21, SOX-A, and transcription factor SOX-21.