TGFB1 and Epstein-Barr virus infection: To confirm that endogenous levels of BZLF1 and Oct-2 are able to interact in a B-cell environment, the EBV-positive BL cell line, MutuI, was treated with TGF-β to induce the lytic form of EBV infection, and cellular extracts were co-immunoprecipitated with anti-Oct-2 or control antibodies.