Fig. 1.

Pathways involved in establishment of senescence cell cycle arrest. Telomeric and environmental cues trigger senescence-associated cell cycle arrest via pathways regulated by the tumour suppressors p53 and pRb. Growth arrest can be reinforced by autocrine signalling loops modulated by NF-κB and C/EPB (Adams, 2009), and feedback via p21-p38MAPK-TGFβ and ROS (Passos et al., 2010). These pathways can be manipulated to delay or prevent onset of senescence by the experimental interventions in the boxes. The figure shows selected pathways and is simplified for clarity. ROS, reactive oxygen species.