TAP2 and neoplasm: The activation of STAT3 shaped by microenvironmental cues including hypoxia can downregulate components of the MHC-I antigen-processing machinery (e.g., TAP1/TAP2), thereby impairing antigen display; activated SUMOylation can limit MHC-I antigen presentation and reduce tumor immunogenicity; preliminary preclinical studies on PDAC with SUMO-pathway blockage indicate the activation of antitumor immunity [109,110,111].