Demethylation of specific HERV families, including HERV-W, HERV-K and HERV-H, has been reported in various cancers.65 Moreover, demethylation of TEs correlates with their transcriptional activation in prostate cancer.27 This indicates that where HERV transcription is increased in cancer cells, it is likely due in part to hypomethylation of their LTRs. The gene discussed is ERVW-1; the disease is cancer.