Cellular senescence can be described as a state of stable cell cycle arrest in response to diverse stresses. Senescence is a collective phenotype of multiple effectors, and their intensity and combination can be different depending on triggers and cell types. In this review, Salama et al. summarize effector mechanisms and highlight some key components of the collective phenotype of senescence.
Cellular senescence is a stress response that accompanies stable exit from the cell cycle. Classically, senescence, particularly in human cells, involves the p53 and p16/Rb pathways, and often both of these tumor suppressor pathways need to be abrogated to bypass senescence. In parallel, a number of effector mechanisms of senescence have been identified and characterized. These studies suggest that senescence is a collective phenotype of these multiple effectors, and their intensity and combination can be different depending on triggers and cell types, conferring a complex and diverse nature to senescence. Series of studies on senescence-associated secretory phenotype (SASP) in particular have revealed various layers of functionality of senescent cells in vivo. Here we discuss some key features of senescence effectors and attempt to functionally link them when it is possible.