P53 anticancer gene is a tumor suppressor gene. P53 is an important anticancer gene whose wild type prevents cancer by causing apoptosis in cancer cells; it also functions to help repair defects in cellular genes. The P53 anticancer gene acts to slow down or monitor cell division under normal conditions. P53, the gene that inhibits cancerous changes in cells, determines the extent of DNA mutation; if the mutation is small, this gene prompts the cell to repair itself. If the DNA mutation is large, P53 induces apoptosis. After the mutation of the P53 gene, the P53 gene changes from an oncogene to an oncogene due to a change in its spatial conformation and the loss of its role in regulating cell growth, apoptosis and DNA repair.