Transforming growth factor β receptor-1 (TGF-β R1) plays an essential role in carbon nanotube-induced fibrogenesis by enhancing collagen production in lung fibroblasts. TβR-dependent signals plays a crucial role in cell growth and differentiation, and polymorphism or mutation of TGF-β R1 leads to head and neck cancer. Activin receptor-like kinase 5 (ALK5) or TGF-β R1 promotes the phosphorylation of small mothers against decapentaplegic (Smad) 2 and Smad3. Activated ALK5 inhibits migration and proliferation of endothelial cells (ECs). ALK1 acts as an antagonist for ALK5/Smad signaling. Mutation of TGF-β R1 can also cause autosomal dominant skin cancer called multiple self-healing squamous epithelioma (MSSE) or Ferguson-Smith disease (FSD).
