ACTA2 and Biliary tract obstruction: As a result of bile duct obstruction, quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that there was an increase in mRNA expression of transforming growth factor (Tgf)-β, the main profibrogenic molecule, of alpha-smooth muscle actin (Acta2), a marker of hepatic stellate cell activation, and of collagen fibrils (Collagen 1A1, Col1a1) as well as of matrix metalloproteinases (mmp-2, -9, and -13) compared with the respective sham controls (Fig. 2C).