Considering the broad expression of ERV Env in murine (and human) cancers [17,20], the goal in this study was to show that our vaccination strategy could work both therapeutically (clearing ERV-expressing cancers) and prophylactically (preventing the growth of other cancer types expressing ERVs), by generating potent ERV-specific effector and memory T cell responses. The gene discussed is ERVW-1; the disease is cancer.