Anti-placenta enriched 1 antibodies are used for the immunodetection of the protein encoded by the PLAC1 gene. In humans, the canonical protein has a reported length of 212 amino acid residues and a mass of 23.6 kDa. It is known to be a secreted protein. It is notably expressed in the placenta. A member of the PLAC1 protein family, it is believed to play a role in placental development. Other names for this target antigen include OOSP2B, OOSP2L, placenta-specific protein 1, cancer/testis antigen 92, placenta specific 1, and CT92. Gene orthologs have been identified in the mouse, rat, bovine and chimpanzee species.