The important role of the cytokine TGF-β in the tumorigenic effect of MSCs is further highlighted by experiments from Shangguan et al. work: By transducing MSCs with activin membrane-bound inhibitor, a TGF-β receptor with inactive cytoplasmatic domain, a repression of the TGF-β axis could be achieved and the tumor protective properties of MSCs in a breast cancer model could be abrogated [40]. Here, TGFB1 is linked to breast carcinoma.