TGFB1 and cancer: TGF-β signal transduction can be stimulated in late-stage tumors (“The TGF-β Paradox” [85, 86] i.e. early-stage cancers are less sensitive to TGF-β inhibitor, whereas many late-stage cancers are stimulated by TGF-β, either directly through increased receptor levels or indirectly by effects on the micro-environment of the cells).