TGFB1 and neoplasm: Although TGFβ is a strong growth inhibitor, elevated TGFβ signaling in tumors contributes to carcinoma progression and metastasis.14 In many types of cells, TGFβ-induced growth inhibition is mediated through SMAD-dependent inhibition of the expression of the c-MYC oncogene, cyclin-dependent kinases (CDKs) and CDC25A.15,16 It is poorly understood how TGFβ switches from a tumor suppressor to a promoter of tumorigenesis and metastasis.