SiRNA mediated knock-down of annexin A5 expression and likewise blockade of syncytin-1 by a synthetic peptide or shRNA markedly impaired the generation of multinucleated PC3 cells and PC3 × muscle cell heterokaryons [66] supporting the requirement of syncytin-1 and annexin A5 in prostate cancer cell fusion. This evidence concerns the gene ERVW-1 and prostate cancer.