Figure 5: TGFβ antagonists and inhibitors. Blocking the TGFβ signaling pathway provides for a unique therapeutic opportunity against tumor metastasis. As such, several approaches to develop new therapeutic tools that would interfere with TGFβ signaling have been undertaken in recent years. Blocking antibodies, peptide inhibitors, kinase inhibitors, soluble receptors, and antisense oligonucleotides are all being tested, some of which are at different phases of clinical trials. In future, more specific approaches may involve targeting specific microRNAs or making use of RNA interference approaches to block expression of specific downstream TGFβ pro-metastatic targets (e.g., p21).