Cytokines produced by megakaryocytes and monocytes such as PDGF, TGF-β, VEGF and β-FGF have been shown to play an important role in the development of secondary stromal proliferation, and the TGF-β secreted by the tumor cells has been suggested to play an important role in the development of MF conferring a direct relation between lymphoma and MF. The gene discussed is TGFB1; the disease is lymphoma.