PSMD4 and malignant colon neoplasm: On human colon cancer cells HCT116 and mice colon cancer cells MC38, Xu et al. [45] discovered that ATL I could bind to the target protein PSMD4 and enhance immunoproteasome antigen processing activity and MHC-I-mediated antigen presentation, increasing the cytotoxic response of CD8+ T cells and improving tumor response to immunotherapy.