Figure 1.

Morphological and metabolic changes in senescent cells. Markers of cell senescence include changes in β-gal activity caused by increased lysosome content and activity, the loss of lamin B1 caused by the changes in the nuclear envelope, the increase of lipofuscin labeled by Sudan black B staining, and morphological changes, such as flat cell bodies. Senescence-associated secretory phenotype- (SASP-) related factors, such as TNFα, IL-1α, IL-1β, and matrix metalloproteinase (MMP) and loss of nuclear localization of HMGB1 are also common markers of senescence.