XBP1 and hepatocellular carcinoma: Melanoma: SIRT7 activates IRE1α–XBP1 stress signaling to upregulate PD-L1 and induce immune evasion. HCC: SIRT7 deacetylates MEF2D to suppress PD-L1. PDAC: SIRT7 cooperates with DDX3X to increase PD-L1.