The specificity of this monoclonal antibody to its intended target was validated by HuProt™ Array, containing more than 19, 000, full-length human proteins. TP53/3156R binds to the C-terminus (aa370-378) of both wild type and mutated p53. When microinjected into nuclei, TP53/3156R blocked re-entry into the S-phase of the cell cycle. Mutation and/or allelic loss of p53 is one of the causes of a variety of mesenchymal and epithelial tumors. If it occurs in the germ line, such tumors run in families. p53 Binds to a DNA consensus sequence, the p53 response element, and it regulates normal cell growth cycle events by activating transcription of genes, involved either in progression through the cycle, or causing arrest in G1 when the genome is damaged. In most transformed and tumor cells the concentration of p53 is increased 51000 fold over the minute concentrations (1000 molecules cell) in normal cells, principally due to the increased half-life (4 h) compared to that of th