In contrast to other (H)ERVs, Mangeney et al. found that the ISD of Syncytin-1 is not able to suppress allogeneic tumour rejection, but this immunosuppressive capability could be achieved by exchanging amino acids 14 and 20 of the Syncytin-1 ISD with the corresponding amino acids of the related Mason–Pfizer monkey virus, without affecting Syncytin-1′s fusogenicity [30]. The gene discussed is ERVW-1; the disease is neoplasm.