International Journal of Molecular Sciences Article Activin A-Smad Signaling Mediates Connective Tissue Growth Factor Synthesis in Liver Progenitor Cells Ze-Yang Ding 1, Guan-Nan Jin 1,2, Wei Wang 1, Yi-Min Sun 1, Wei-Xun Chen 1, Lin Chen 1, Hui-Fang Liang 1, Pran K. Datta 3, Ming-...