RB1 and cancer: For example, cell cycle arrest in quiescent cells can be reversible; p16 can be detected in several cancer cells, especially in HPV‐related cancer cells in which Rb is inactivated by HPV oncoprotein E7 independent of p16 [149]; p21 can be upregulated upon transient DNA damage; Lamin B1 can be downregulated independent of cellular senescence; γH2AX can be detected in G2/M phase cells; SA‐β‐gal activity can be increased in quiescent cells and several cancers; SASP‐like inflammatory response can occur independently of cellular senescence by innate immune responses in other types of cells.