Introduction

p53 is a transcription factor and also a tumor supressor protein. aberrant forms of this protein are found in numerous cancers.
Li Fraumeni Syndrome
One copy of normal p53 in germline leads to numerous tumor. this condition is called Li-Fraumeni syndrome.
Regulation
p53 is regulated by proteolytic mechanisms. upon binding to Mdm2, the protein is ubiquitinated and then degrades in proteosomes. phosphorylation by other factors prevent degradation of p53.