However, other studies have shown that, in colorectal cancer, methionine dietary restriction can simultaneously activate Type-I interferons, such as IFN-α and IFN-β, to enhance major histocompatibility complex class I expression, and Type-II interferon, such as IFN-γ, to increase PD-L1 expression in tumor cells.39 This evidence concerns the gene IFNG and neoplasm.