These observations were later confirmed in a series of BL cell lines (Mutu-I, Raji and B95-8) in which TGF-β1 induced BZLF1/Zta expression by an indirect mechanism which required the ERK 1/2 MAPK kinase pathway; Smad signalling alone was not sufficient to mediate TGF-β1 induction of Zta [164]. The gene discussed is TGFB1; the disease is Burkitt lymphoma.