COL1A1 and Hepatic fibrosis: However, we did not observe a direct fibrogenic effect of GDF7 treatment of human LX2-HSC in vitro, as it did not affect gene expression of COL1A1, ACTA2 and CTGF. Apart from directly regulating HSC activation, some BMPs/GDFs may ameliorate hepatic fibrosis by increasing expansion of liver progenitor cells (LPC) that aid in liver regeneration by differentiation to cholangiocytes or hepatocytes [41].