To verify that the PAI-1 inhibitor activated tumor immunity by reducing PD-L1 expression, we transplanted MC38 cells subcutaneously into immunodeficient mice with a double Rag2 and Il2rg (IL-2 receptor γ chain) knockout (Rag2/IL-2Rγ-double knockout, DKO) and no T, B, or NK cells; wild-type (WT) mice served as the control. The gene discussed is SERPINE1; the disease is neoplasm.