P53 is responsible for the integrity of the genetic code which is written in DNA.

To ensure stable and correct genetic information, p53 acts as a transcription-factor and transactivates fundamental genetic programs. Most importantly, p53 controls the cell cycle, mediates DNA repair and initiates cell suicide (apoptosis).

Playing these cell inherent programs, p53 prevents passing on defective genetic information to the next generation and is therefore known as GUARDIAN OF THE GENOME.

The importance of p53 can be estimated by the fact that a single gene is curcially involved in two cellular conditions, which are as different as can be: