ERVW-1 and primary effusion lymphoma: Using the KSHV + primary effusion lymphoma cell line BCBL-1 and inducing agents 12-O-tetradecanoylphorbol-13-acetate (TPA: a phorbol ester) or valproic acid (VPA: another HDACi), we again examined Syncytin-1 expression by western blot following 24 h treatments (Figure 4A).