p53 tumour suppressor protein, illustration. Also known as TP53, activation of this tumour suppressor induces apoptosis, cell cycle arrest, or senescence in response to distinct stimuli, including DNA (deoxyribonucleic acid) damage or aberrant oncogene activation. A p53 mutant protein goes hand in hand with a higher gene expression. Consequently, higher protein levels of p53, due to a mutation, can also be regarded as an immunogenic trigger.