An up-regulation (FC ≥2) of the expression levels of 8 HERV genes was observed with a higher frequency in guadecitabine- or DAC- vs. AZA-treated melanoma cells: 21.4% and 7.1% vs. 0% (Syncytin-1), 28.5% and 35.7% vs. 14.2% (Syncytin-2), 35.7% and 57.1% vs. 7.1% (ENV-T), 42.8% and 42.8% vs. 0% (ERV9-1), 35.7% and 42.8% vs. 35.7% (ENV-MER34), 78.5% and 78.5% vs. 28.5% (ERV-FXA34), 21.4% and 64.2% vs. 0% (ENV-Fb1) and 28.5% and 50% vs. 7.1% (ENV-Fc2). Here, ERVFRD-1 is linked to melanoma.