In 1979 p53 was discovered by Arnold Levine and David Lane.

TUMOR CELLS are characterized by the potential for uncontrolled cell division.

Malignant transformation goes hand in hand with loss of tumor suppressor function. The p53 gene is known as a most powerful tumor suppressor and is most frequently inactivated in human cancer by gene mutation.

Overall about 50% of human cancers exhibit defects in the p53 gene.

Additionally, there seem to be numerous alternative ways to inactivate p53. Such mechanisms can be located at different cellular levels. Their importance for cancer development cannot be estimated until now.

(e.g  protein products of the human papilloma virus and the hepatitis B virus (E6, HbX respectively) are able to bind the p53 protein. This complex can prevent p53 from binding to DNA and acting as transcription factor.)