Secondly, to substantiate that the uptake of mitochondria by cancer cells is mediated by these HERV proteins and their cognate receptors, we blocked these proteins using specific antibodies (anti-syncytin 1, anti-syncytin 2, Figure 9, panels A3-4, or anti-SLCA5 and anti-MFSD2, Figure 9, panels A5-6). The gene discussed is ERVFRD-1; the disease is cancer.