SMAD3 and cancer: For instance, Smad3 inactivation is known to accelerate cancer metastasis.42, 43, 44, 45, 46 Given the complicated roles of TGF-β pathway in the regulation of cancer metastasis,47, 48 it remains unclear whether KLF17 may cooperatively or discordantly affect TGF-β signaling in different tumor metastasis.