The p53 tumour suppressor protein plays a pivotal role in coordinating the cellular response to a range of environmental and intracellular stresses. Multiple stress signals that activate p53 include hypoxia, telomere erosion, oncogenes and DNA damage, which is the best studied of them all. Activated p53 translocates into the nucleus and acts as a transcription factor to regulate its target genes, resulting in the anti-proliferative affects of p53 like cell cycle arrest, apoptosis, and DNA repair. The functions of p53 are regulated by several mechanisms including post-translation modifications, protein-protein interaction, etc. Doctor of Philosophy (SBS)