CD80 and neoplasm: Interestingly, a recent investigation reported hypermethylation of the CD80 promoter in mice tumours, and treatment with decitabine, a DNA methyltransferase inhibitor, was found to enhance CD80 expression in EL4 cells via demethylation of CpG dinucleotide sites in the promoter of CD80 gene resulting in T lymphocyte infiltration into tumors and, ultimately, in tumor rejection [26].