A number of ELISA Kits are available that target U21.1, an alias of the protein, heterogeneous nuclear ribonucleoprotein U. The human protein is encoded by the gene HNRNPU. The protein's cellular localization is indicated to be cytoplasmic and nuclear. Additional synonyms or past names for this protein may include: EIEE54, GRIP120, HNRNPU-AS1, HNRPU, SAF-A, SAFA, U21.1, hnRNP U, pp120. Homology is conserved in other species, such as Mouse, Rat.