TP53 and cancer: In contrast, overexpression of p53β induces cellular senescence by the upregulation of p53 target genes such as p21Waf1/Cip1 via cooperation with full-length p53.13 Although in T lymphocytes, the role of these two p53 isoforms as potential regulators of cellular senescence has been reported,20 their function in more complex and tissue-specific context, including immune-related disorders or cancer remains unexplored.