Ovarian cancer cell lines with hypermethylation/MHC-Ilow (OAW42) or hypomethylation/MHC-Ihigh (SK-OV-3 and OVCA-420) treated with IFNγ, a cytokine well established for inducing MHC-I expression33,34, showed increased MHC-I protein expression on the tumour cell surface (Fig. 5b and Supplementary Fig. 6a, b), supporting a reversible epigenetic mechanism rather than a hard-wired irreversible genetic modulation for MHC-I expression. The gene discussed is IFNG; the disease is ovarian cancer.