In a variety of MHC class II-negative tumor cells, elevated levels of chromosomal histone deacetylation and CpG site methylation on the CIITA promoter have been detected; however, treatment with HDACi or DNA methyltransferase inhibitors (DNMTi) increased the expression of MHC II, and the underlying mechanism may be the transcriptional activation of the CIITA gene (21). The gene discussed is CIITA; the disease is neoplasm.