Anti-FBP21 antibodies enable researchers to detect and measure the FBP21 antigen in biological samples. This target is a reported synonym of the WBP4 gene, which encodes WW domain binding protein 4. This protein is known to function in RNA splicing, among other biological roles. The human version of FBP21 has a canonical amino acid length of 376 residues and a protein mass of 42.5 kilodaltons, although 2 isoforms have been identified. It is reported to be localized in the nucleus of cells and widely expressed in many tissue types.