Table 1.

The different markers of senescence that are commonly used.

Senescence marker	Description
SA β–Gal	Senescence-associated beta-galactosidase is an enzymatic stain that can be used on cells and tissues (Fig. 1) (38), with its activity associated with an increase in lysosomes biogenesis found in senescent cells (39).
γH2AX	Histone H2A variant is DDR marker that is phosphorylated at serine 139 upon DNA double-strand breaks (40).
	γH2AX can also be used to detect nuclear membrane bleb structures that contain cytosolic chromatin fragments (CCFs) in the cytoplasmic compartment of senescent cells (41, 42).
	CCFs are known to be involved in the secretion of proinflammatory SASP through the activation of the cGAS-STING-NFκB pathway (42).
	Recently, it has been shown that impairment of autophagy is linked to CCFs formation, and metformin-induced activation of autophagy can reduce CCFs levels and suppress SASP secretion (43).
	CCFs and SASP profile in senescent primary human fibroblasts have also been associated with mitochondrial dysfunction via a retrograde ROS-JNK signaling pathway (44).
Lamin B1	Is a protein of the nuclear envelope and its expression is reduced during SIPS-associated nuclear membrane blebbing (45, 46).
Ki67, BrdU, PCNA	Are typical proliferation markers used to detect growth arrest (47, 48). High expression of these markers correlates with a high proliferation rate, and their decrease in expression is used in conjunction with other markers to confirm cellular senescence.