High endogenous expression of transforming growth factor-β2 (TGF-β2), which is an isoform of TGF-β [35], was able to direct melanoma cells to form brain metastases within the parenchyma of mice, while low expression of TGF-β2 induced brain metastasis within the ventricles and leptomeninges [36]. The gene discussed is TGFB2; the disease is melanoma.