To test whether inhibition of DNA methyltransferase activity can induce upregulation of MHC genes in human breast cancer patients, we explored gene expression data from longitudinally-collected biopsies of breast cancer patients treated with the DNA methyltransferase inhibitor 5′-azacytidine in combination with entinostat (HDAC inhibitor)11. The gene discussed is HDAC9; the disease is breast carcinoma.