On Dec. 20, 1984, a team of scientists announced that a cDNA clone for human p53 cellular tumor antigen has been isolated and characterized. This clone contains the complete 3′-untranslated region and most of the open reading frame for the protein. Nucleotide sequence analysis revealed that p53 mRNA contains an Alu repeat in the 3′-untranslated region. Hybridization selection experiments showed this clone was capable of selectively binding p53 mRNA.

The expression of p53 mRNA and the genomic organization of the p53 gene do not appear to be altered in cells that contain high and low levels of p53 protein. This indicates that p53 is regulated in these cells at the post-transcriptional level.

The p53 gene like the Rb gene, is a tumor suppressor gene (i.e., its activity stops the formation of tumors). If a person inherits only one functional copy of the p53 gene from their parents, they are predisposed to cancer and usually develop several independent tumors in a variety of tissues in early adulthood.