Figure 2.

Molecular pathways involved in the senescence-associated growth arrest. A spectrum of stressors induces senescence-associated growth arrest. Cell cycle arrest is mediated through 2 main pathways, p16^INK4a/pRb and p53/p21^CIP1. Both collide in the activation of the pRB, which prevents cells to enter the S phase of the cycle. ATM = ataxia telangiectasia mutated; ATR = ATM and Rad3-related; CDK = cyclin-dependent kinase; DDR = DNA damage response; p16 = cyclin-dependent kinase inhibitor 16; p21 = cyclin-dependent kinase inhibitor 21; p53 = tumour suppressor p53 protein; pRB = tumour protein of the retinoblastoma.