OBJECTIVE: We have recently reported that therapies targeting TGF-β1 signaling were effective to prevent the anaplastic thyroid cancer (ATC) cell growth, but not the invasion. Phosphatidylinositol 3-kinase (PI3K)/AKT signaling are activated in ATC and play a major role in ATC invasion. Herein, we examined the effects of targeting TGF-β1 by shRNA in combination with pan-AKT inhibitor, MK-2206 on growth and metastasis of ATC xenografts implanted in severe combined immunodeficient mice.