Research has shown that MMP-2 deficiency leads to inhibition of the activation of transforming growth factor-β (TGF-β) and the Smad2/3 pathway, emphasizing the interaction between MMP-2 and other signaling proteins involved in the progression and occurrence of thoracic aortic aneurysm [12]. The gene discussed is MMP2; the disease is thoracic aortic aneurysm.