The First Twenty-Five Years of p53 Research -- Regulation of p53 DNA Binding -- 20 Years of DNA Damage Signaling to p53 -- Gatekeepers of the Guardian: p53 Regulation by Post-Translational Modification, MDM2 and MDMX -- Regulation of the p53 Response by Cellular Growth and Survival Factors -- P53, Cell Cycle Arrest and Apoptosis -- P53 Has a Direct Pro-apoptotic Action at the Mitochondria -- Ma…