Using mouse melanoma and breast tumor models, we found that PU.1 inhibition by DB suppressed tumor growth, likely through promoting CXCL9 expression in TAMs, which enhances the tumor infiltration of lymphocytes, including CD4+ Th1, CD8+ cytotoxic T lymphocytes (CTLs), and NK cells. The gene discussed is CXCL9; the disease is neoplasm.