Anti-tumor protein p53 antibodies are used in the immunodetection of the protein encoded by the TP53 gene. In humans, the canonical protein has a reported length of 393 amino acid residues and a mass of 43.7 kDa. Its subcellular localization is in the nucleus, mitochondria, ER, and cytoplasm. Alternative splicing is reported to yield 9 different isoforms for this protein. It is ubiquitously expressed across many tissue types. A member of the P53 protein family, it is known to act as a tumor suppressor in many tumor types; induces growth arrest or apoptosis depending on the physiological circumstances and cell type. Post-translational modifications have been described, including methylation, O-glycosylation, ubiquitination, sumoylation, acetylation and phosphorylation. Other names for this target antigen include BMFS5, LFS1, P53, TRP53, cellular tumor antigen p53, antigen NY-CO-13, mutant tumor protein 53, and BCC7.