In this study, we demonstrate that cytotoxic stress by etoposide induces accumulation of mitochondria in human U87 glioblastoma cells, which were associated with different HERV-envelope proteins including, significantly, HERV-WE1 (syncytin-1) and HERV-FRD1 (syncytin 2). The gene discussed is ERVW-1; the disease is glioblastoma.