FIG. 1.

Phenotypes (“building blocks”) of the senescent state and observable markers associated with it. Although all phenotypes are tightly interrelated (not shown), individual phenotypes might be more or less strongly activated in individual senescent cells depending on contexts including senescence inducer, cell type, tissue environment, and others. For each phenotype, there are multiple markers that enable assessment of its involvement in a given senescent state. CI, complex I of the mitochondrial electron transport chain; DDF, DNA damage foci; DDR, DNA damage response; ROS, reactive oxygen species; SADS, senescence-associated distension of satellites; SAHF, senescence-associated heterochromatin foci; SAMD, senescence-associated mitochondrial dysfunction; SASP, senescence-associated secretory phenotype; SCARS, DNA segments with chromatin alterations reinforcing senescence; TAF, telomere-associated foci; TL, telomere length. Color images are available online.