PF4 and neoplasm: The expression levels of ccl-2 (MCP-1), ccl-20 (MIP-3), ccl-7 (MCP-3), CXCL-4 (PF-4), CXCL 1 (Gro -), and CXCL-12 (SDF-1) are also significantly increased in replicative senescent cells [167], allowing the disruption of the blood-tumor barrier integrity and greater spread of tumor cells.