Using DNMT and HDAC inhibitors, 81 genes including functionally validated anti-angiogenesis genes (clusterin, fibrillin 1, and quiescin Q6) were identified specifically and epigenetically silenced in tumor-conditioned versus quiescent ECs.461 Although the mechanism of DNMT-mediated gene silence remains elusive as no significant DNA methylation alteration was detected in the promoter CpG islands of seven tested genes, histone modification change, i.e., loss of H3 acetylation and H3K4 methylation, was proposed to be associated with the gene silence. The gene discussed is DNMT1; the disease is neoplasm.