“…There are many substances secreted by senescent cells. First, these cells secrete proteins such as interleukin (IL)-1, IL-6, and IL-8 [ 40 ], which can affect surrounding cells by cell surface receptors, chemokines such as CXCL family-1/2/4/5/6/8/12, MCP-2/4, CCL family members 2/3/4/5/7/8/13/16/20/26, and CXCR-2 binding factor [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ], and insulin-like growth factor (IGF) pathway components (IGFBP-2/3/4/5/6 and their regulators IGFBP-rP1/rP2/7), which influence the microenvironment of senescent cells [ 49 , 50 , 51 , 52 , 53 ]. Second, senescent cells secrete soluble factors such as colony-stimulating factors (CSFs), including granulocyte macrophage-CSF and G-CSF, osteoprotegerin, prostaglandin E2 (PGE2), and COX-2, which is the enzyme responsible for the production of PGE2 and other prostaglandins [ 46 , 50 , 54 ].…”