SERPINE1 and neoplasm: For example, PAI-1 activates the p53/p21 pathway, promotes cellular senescence via SASP induction, and senescent cells secrete SASP factors such as IL-6 and MMPs that recruit M2-type TAMs and regulatory T cells (Tregs), thereby establishing an immunosuppressive TME and ultimately accelerating tumor progression [34,35] (Figure 2).