p53 is the most important tumor suppressor. It arrests cell cycle in response
to stress, stimulates DNA repair, and induces senescence or apoptosis of cells that have
unrepairable damage. p53 level and activity are kept low by the E3 ubiquitin ligase
Mdm2, which ubiquitinates p53 targeting it for proteasomal degradation. Additional
post-translational modifications of p53 such as phosphorylation, methylation,
acetylation, and others, signal the cell’s internal condition to p53 and modulate its
activity.
Keywords: ATM, ATR, Apoptosis, Cell cycle, Cell cycle arrest, Cancer, DNA
damage, Mdm2, p53, p63, p73, Tumor suppressor.
