Anti-P antigen family, member 4 (prostate associated) antibodies enable researchers to detect and measure the P antigen family, member 4 (prostate associated) antigen in biological samples. This target is a reported synonym of the PAGE4 gene, which encodes PAGE family member 4. This protein is known to function in the regulation of apoptosis and the response to oxidative stress, among other biological roles. The human version of P antigen family, member 4 (prostate associated) has a canonical amino acid length of 102 residues and a protein mass of 11.2 kilodaltons. It is reported to be localized in the nucleus, mitochondria, and cytoplasm of cells and notably expressed in the placenta. Other names for this target antigen include CT16.7, GAGE-9, and GAGEC1.