p53 isoforms Δ133p53 and p53β are endogenous regulators of replicative cellular senescence

p53-mediated replicative cellular senescence is a barrier to tumorigenesis. The p53 isoforms p53β and Δ133p53 are respectively induced and downregulated during replicative senescence. Elevated p53β and reduced Δ133p53 levels are observed in colon adenomas with senescent phenotypes, whereas the opposite is found in colon carcinomas that might have escaped from the senescence barrier.