TGFB1 and pulmonary fibrosis: However, as a transmembrane glycoprotein, CD147 was also reported to stimulate hepatic stellate cell (HSC) activation and proliferation by a TGF-β1-CD147 self-sustaining network, promoting the upregulation of fibrogenesis-related genes and liver fibrosis.28,29 We then focused on the possible contribution of CD147 to the activation of fibroblasts in pulmonary fibrosis in addition to the already established functions in COVID-19 pathogenesis.