PSMB9 and neoplasm: These contrasting functions are schematically summarized in Figure 5, which illustrates context-dependent pro-tumor mechanisms (e.g., AML stemness, IL-17-driven progression, proteostasis support) versus anti-tumor effects (e.g., PSMB9 tumor suppression, neoantigen diversification, enhanced immunogenicity), highlighting the immunoproteasome’s dualistic role in cancer biology.