Interferons (IFN), in particular IFNγ, increase expression of pMHC-I complexes on tumor cells by concomitantly upregulating transcription of MHC-I heavy chains, B2M, most components of the peptide-loading complex and three unique components of the immunoproteasome (low-molecular-weight polypeptide (LMP)2/Proteasome 20S subunit beta (PSMB)9, LMP7/PSMB8 and the multicatalytic endopeptidase complex-like (MECL)-1/PSMB10). This evidence concerns the gene B2M and neoplasm.