B2M and cancer: Hypermethylation of the promoters of MHC-I heavy chains, B2M, APM components and/or NLRC5, leads to the suppression of MHC-I expression that is can be overcome with DNA methyltransferase inhibitors (DNMTi) as demonstrated for breast, lung, colon, thyroid cancers, human papillomavirus (HPV)-related cancers, sarcomas and gliomas [105,106,107,108,109].