To (TGF)β or not to (TGF)β: Fine-tuning of Smad signaling via post-translational modifications

Smad proteins are key signal transducers for the TGF-β superfamily and are frequently inactivated in human cancers, yet the molecular basis of how their levels and activities are regulated remains unclear. Recent progress, discussed herein, illustrates the critical roles of Smad post-translational modifications in the cellular outcome to TGF-β signaling.