Tenovin-1 inhibits the protein-deacetylating activities of SIRT1 and SIRT2. Tenovin-1 is also a p53 activator and elevates the amount of p53 protein within 2 hr of treatment, without altering p53 mRNA levels. Tenovin-1 protects against MDM2-mediated p53 degradation via ubiquitination.