Expression of collagen α1(I) in a model of cholestasis-induced liver fibrosis. Transgenic mice with green fluorescence protein reporter gene under the direction of the collagen α1(I) promoter/enhancers were subjected to bile duct ligation for 2 weeks. (A) Collagen α1(I) was markedly expressed by activated HSCs, but not hepatocytes, in the hepatic parenchyma. Magnification, ×200. (B) Collagen α1(I) is markedly expressed by myofibroblasts around proliferating bile ducts. HSCs proliferate to initiate collagen deposition in the hepatic parenchyma. Magnification, ×40.