SMAD2 is a receptor-regulated SMAD protein that functions as a key intracellular signal transducer in TGF-β and activin signaling pathways 1. Upon activation by TGF-β type I receptor kinases, SMAD2 translocates from the cytoplasm to the nucleus where it forms complexes with SMAD4 to activate transcription of target genes 1. SMAD2 plays context-dependent roles in cancer: while potentially acting as a tumor suppressor in colorectal carcinoma, selective suppression of SMAD2 (with SMAD3 intact) paradoxically switches TGF-β signaling toward a prometastatic phenotype in non-small cell lung cancer 2. SMAD2 also cooperates with TGIF2 to promote epithelial-mesenchymal transition and cancer stem cell properties in pancreatic cancer through SOX2 co-regulation 3. Beyond cancer, SMAD2/3 phosphorylation is activated during trophoblast differentiation and contributes to placental development 4. In cardiac stem cells, TGF-β/SMAD2/3 signaling modulates proliferation and senescence, suggesting therapeutic potential for heart failure 5. SMAD2 activation also mediates pathological responses, including liver fibrosis via TGF-β/SMAD2/3 axis activation by environmental stressors 6 and cancer metastasis promotion through MPS1-dependent phosphorylation 7. Mutations in SMAD2 are associated with non-small cell lung cancer pathogenesis 8.