Anti-Pir121 antibodies enable researchers to detect and measure the Pir121 antigen in biological samples. This target is a reported synonym of the CYFIP2 gene, which encodes cytoplasmic FMR1 interacting protein 2. This protein is known to function in the apoptotic pathway and axon guidance, among other biological roles. The human version of Pir121 has a canonical amino acid length of 1278 residues and a protein mass of 148.4 kilodaltons, although 2 isoforms have been identified. It is reported to be localized in the nucleus and cytoplasm of cells. Other names for this target antigen include DEE65 and EIEE65.